Progress 10/01/09 to 09/30/14
Outputs
Target Audience: Major audience for this project has included the international science community, i.e., scientists, engineers, students, researchers, involved in natural fibers, biopolymers and nanocellulose research. These include professional conferences organized by the American Chemical Society's Division of Cellulose and Renewable Materials, the Fiber Society and the UK Polymer Fibres as well as a number of fiber and polymer materials journals. The California Rice Research Board (CRRB) has provided strong support for this project. So are the international natural fiber community as well as other European research organizations such as nova-Institut GmbH (a private organization devoted to green chemistry in Germany), VTT Technical Research Center of Finland. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided? Two graduate students and two undergraduate students have been trained to participate in research related to this project. Two postdoctoral researchers are fully involved on research activities as well. In addition, two international visiting PhD students and two international visiting professors have participated on this project. How have the results been disseminated to communities of interest? Oral presentations have been made at professional conferences, including American Chemical Society national and regional meetings, the Fiber Society meetings, International Conference on Modern Materials and Technology as well as visits with international delegates and commodity groups. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
Mechanically robust cellulose nanofibril (CNF) aerogels with ultralow density (8 mg/cm3), superior porosity (99.5%), super water absorbency (104 g/g water/dried mass), high crystallinity (68.5%) as well as exceptional wet resiliency and water activated shape recovery were facilely fabricated for the first time by ice-crystal templated self-assembly of TEMPO oxidized CNFs via cyclic freezing-thawing. With ultrathin widths (1-2 nm), high aspect ratios (several hundreds) and numerous surface polar hydroxyls and carboxyls, TEMPO oxidized CNFs behaved similarly to aqueous soluble polymers to form strong freestanding hydrogels by repetitive freezing (-20 °C, 15 h) and thawing (room temperature, 9 h). The spaces occupied by the several hundred microns wide ice crystals were well preserved upon freeze-drying, deriving macroprous CNF aerogels with over 99% several porosity of interconnected pores. The freezing induced self-assembling of CNFs was observed at a low concentration of 0.05 wt%, whilst more ordered macroporous honeycomb structures were observed at and above 0.2 wt%. Exchanging water in the CNF hydrogel with tert-butanol generated hierarchical CNF aerogel containing hundred microns sized macroscopic as well as meso-pores ranging from 2 to 90 nm with further improved specific surface (117.8 m2/g), pore volume (1.19 cm3/g) and water absorption (116 g/g). All CNF aerogels demonstrated super water absorbency, fast water-activated shape recovery in 4 s and reusability for at least 20 times. Ultra-light (1.7 to 8.1 mg/cm3) and ultra-porous (99.5 to 99.9%) aerogels have been assembled from cellulose nanofibrils (CNFs) that were defibrillated from rice straw cellulose at 96.8% yield. The as-prepared aerogels amphiphilic super-absorbents, absorbing 210 and 375 times of water and chloroform, respectively, far superior to any previously reported cellulose aerogels. Vapor deposition with triethoxyl(octyl) silane turned the amphiphilic aerogel more hydrophobic and oleophilic, capable of absorbing 139-356 times of non-polar hydrocarbons, polar aprotic solvents and oils, surpassing all previously reported polymeric, cellulosic and carbonaceous aerogels by 2 to nearly 20 times. These aerogels are excellent amphiphilic super-absorbents for selective oil removal and recovery. An efficient three-step process using toluene/ethanol, NaClO2 and KOH has been successfully devised to isolate pure cellulose from rice straw while generating two filtrates as activated carbon and silica precursors. The NaClO2 dissolution filtrate contains oxidized lignin and hemicellulose as carbon precursors as well as sodium carbonates as activating agents for direct carbonization (800 °C) into highly porous (0.90 cm3/g), high specific surface (997 m2/g) activated carbon particles (100 to 500 nm). The KOH dissolution filtrate contains mainly potassium silicate which could be precipitated by dilute acidified poly(ethylene oxide) and calcinated (500 °C) to pure uniformly sizes (100 to 120 nm), non-porous silica nanospheres. Deriving these additional activated carbon and silica particles along with nanocellulose creates advance materials while fully utilizing all major components in rice straw, the highest quantity agricultural crop by-product in the world. Chitosan-sheath and chitin-core nanowhiskers (CsNWs) have been successfully generated by surface deacetylation of chitin nanowhiskers (CtNWs) in the never-dried state. Acid hydrolysis (3 N HCl, 30 mL/g, 104 C) of pure chitin derived from crab shell yielded 65 % 4-10 nm thick, 16 nm wide and 214 nm long chitin whiskers (CtNWs) that were 86% crystalline and 81% acetylated. Surface deacetylation of CtNWs was robust in their never-dried state in 50% NaOH at a moderate 50 C for 6 h, yielding 92% CsNWs. All deacetylated CsNWs retain the same ?-chitin crystalline core at reduced 50% crystallinity and similar dimensions (4-12 nm thick, 15 nm wide, 247 long) as CtNWs, but reduced 60% acetylation reflecting the deacetylated surface layers. Progressive surface deacetylation was evident by the increased IP as well as increased positive charges under acidic pH and reduced negative charges at alkaline pH with increasing reaction time.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2013
Citation:
Hsieh, Y.-L. Cellulose nanocrystals and self-Assembled nanostructures from cotton, rice straw and grape skin: a source perspective, Journal of Materials Science, 48(22): 7837-7846 (2013)
- Type:
Journal Articles
Status:
Published
Year Published:
2013
Citation:
Jiang, F., Y.-L. Hsieh, Super water absorbing and shape memory nanocellulose aerogels from TEMPO-oxidized cellulose nanofibrils via cyclic freezing-thawing, Journal of Materials Chemistry A, 2: 350-359 (2013).
- Type:
Journal Articles
Status:
Published
Year Published:
2014
Citation:
Pereira, A.G.B., E.C. Muniz, Y.-L. Hsieh, Chitosan-sheath and chitin-core nanowhiskers, Carbohydrate Polymers 107: 158-166 (2014).
- Type:
Journal Articles
Status:
Published
Year Published:
2014
Citation:
Jiang, F., J.L. Dallas, B. K. Ahn, Y.-L. Hsieh, 1D and 2D NMR of nanocellulose in aqueous colloidal suspensions, Carbohydrate Polymers 110: 360-366 (2014).
- Type:
Journal Articles
Status:
Published
Year Published:
2014
Citation:
Hu, S., Y.-L. Hsieh, Preparation of activated carbon and silica particles from rice straw, ACS Sustainable Chemistry and Engineering 2(4): 726-734 (2014).
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Progress 01/01/13 to 09/30/13
Outputs
Target Audience: Major audience for this project has included the international science community involved in natural fibers, biopolymers and nanocellulose research. These include professional conferences organized by the American Chemical Society's Division of Cellulose and Renewable Materials, the Fiber Society and the UK Polymer Fibres as well as a number of fiber and polymer materials journals. The California Rice Research Board (CRRB) has provided strong support for this project. So are the international natural fiber community as well as other European research organizations such as nova-Institut GmbH (a private organization devoted to green chemistry in Germany), VTT Technical Research Center of Finland. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided? Two graduate students and three undergraduate students have been trained to participate in research related to this project. Two postdoctoral researchers are fully involved on research activities as well. In addition, two international visiting PhD students and three international visiting professors have participated on this project. How have the results been disseminated to communities of interest? Oral presentations have been made at professional conferences, including American Chemical Society national and regional meetings, the Fiber Society meetings, International Nature Fiber conference and Wood and Natural Fibers and Nanocellulose and Polymer Chemistry Conferences, as well as visits with international delegates and commodity groups. What do you plan to do during the next reporting period to accomplish the goals? The isolation of cellulose and other biomass components in rice straw will be further optimized from green chemistry and unique performance perspectives. Additional novel nanomaterials will be developed from nanocellulose derived from acid hydrolysis, TEMPO oxidation as well as mechanical defibrillation as well as lignin/hemicellulose streams. Chitin and chitosan based biopolymers and nanowhiskers will be converted into functional nanomaterials as well.
Impacts
What was accomplished under these goals?
Several unique nanofibrous materials have been generated from cellulose and carbon precursors isolated from rice straw. Cellulose nanocrystals (CNCs) and nanofibrils (CNFs) have been isolated from pure rice straw cellulose via sulfuric acid hydrolysis, mechanical blending and TEMPO-mediated oxidation to 16.9%, 12% and 19.7% yields, respectively. Sulfuric acid hydrolysis produced highly crystalline (up to 90.7% CrI) rod-like (3.96-6.74 nm wide, 116.6-166 nm long) CNCs with similarly negative surface charges (-67 to -57 mV) and sulfate contents but decreasing yields and dimensions with longer hydrolysis time. Mechanical defibrillated CNFs were 82.5% crystalline and bimodally distributed in sizes (2.7 nm wide and 100-200 nm long; 8.5 nm wide and micrometers long). TEMPO mediated oxidation liberated the most uniform, finest (1.7 nm) and micrometer long, but least crystalline (64.4% CrI) CNFs. These nanocellulose self-assembled into submicron (153 to 440 nm wide) fibers of highly crystalline (up to 90.9 % CrI) cellulose I? structure upon rapid freezing (-196 °C) and freeze-drying. The self-assembling behaviors were analyzed based on nanocellulose dimensions, specific surfaces and surface chemistries. TEMPO mediated oxidation with 5 mmol/g NaClO/cellulose followed by 30 min mechanical blending generated highly uniform (2.09 nm wide, 1.52 nm thick, up to 1 m long) cellulose nanofibrils (CNFs) at an impressive 96.8% yield. These CNFs from c oupled chemical-mechanical defibrillation contained 1.29 mmol surface carboxyls per g of cellulose or 0.21 COOH/anhydroglucose (AG), representing 70.9% surface C6 primary hydroxyl to carboxyl conversion. Rapid freezing of aqueous CNF suspensions in liquid nitrogen and freeze-drying induced self-assembly of these nanofibrils into highly crystalline (63.2-71.5% CrI) cellulose I beta fibrous materials via ice-crystal templating. The self-assembled fiber morphologies showed strong dependence on CNF morphologies and extents of surface carboxylation. CNFs with 37.3% conversion of surface carboxyls assembled into 125 nm wide fibers whereas wider fibers (327 nm and 497 nm) were assembled from the smaller CNFs and more carboxylated (51.5% and 70.9%, respectively) surfaces. This robust defibrillation-assembly approach offers new versatile and scalable alternatives to fabricate super-fine cellulose fibers with highly crystalline cellulose I beta structure from the by-product of the largest cereal crop in the world. A facile and sustainable approach of fabricating ultrafine (100-500 nm) highly porous activated carbon fibers (ACFs) by electrospinning of aqueous solutions of predominantly alkali lignin (low sulfonate) followed by simultaneous carbonization and activation at 850 oC in N2 has been validated. Incorporating polyethylene oxide (PEO) carrier at only up to one ninth of lignin not only enabled efficient electrospinning into fibers but also retained fibrous structures during heating, alleviating the need for a separate thermal stabilization step. In-situ impregnation of alkali hydroxide activating chemicals at only up to 50% of lignin carbon precursor, i.e., merely one tenths to one quarter of quantities used in manufacturing activating carbon particulates, allowed simultaneous carbonization and activation in single heating. A range of micropore-dominant to mesopore-dominant ACFs were successfully fabricated to contain superior specific surface (>1,400 m2/g) and porosity (> 0.7 cm3/g) tuned by varying the type and contents of alkali hydroxides. This streamlined approach was robust and demonstrated the feasibility and versatility in processing and converting a readily available renewable carbon precursor, lignin, into highly porous activated carbon fibers.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2013
Citation:
Jiang, F., S. Han, Y-L. Hsieh, Controlled defibrillation of rice straw cellulose and self-assembly of cellulose nanofibrils into highly crystalline fibrous materials, RSC Advances, 3(30): 12366-12375 (2013).
- Type:
Journal Articles
Status:
Published
Year Published:
2013
Citation:
Hu, S., Y.-L. Hsieh, Ultrafine microporous and mesoporous activated carbon fibers from alkali lignin, Journal of Materials Chemistry A, 1, 11278-11288 (2013).
- Type:
Journal Articles
Status:
Published
Year Published:
2013
Citation:
Jiang, F. and Y-L. Hsieh, Chemically and mechanically isolated nanocellulose and their self-assembled structures, Carbohydrate Polymers, 95(1): 32-40 (2013).
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Progress 01/01/12 to 12/31/12
Outputs
OUTPUTS: Nanomaterials have been generated from agricultural crop and beverage processing by-products. Rice straw has been fractionated into cellulose, hemicellulose, lignin and silica streams from which further functional nanoproducts are engineered. Grape pomace from wine making process has also been fractionated to generate pure cellulose and cellulose nanocrystals. The phenolic compoments are being explored as precursors for carbon nanofibers and porous products. These biobased nanomaterials and nanofibers demonstrate viable strategies for utilizing under-utilized by-products to achieve novel functionality for advance material applications. Finding from this research have been disseminated in professional conferences (e.g., American Chemical Society, the Fiber Society), in invited talks at meetings with agricultural sectors (rice, wine) and with other university and USDA scientists. PARTICIPANTS: This project has provided research training for undergraduate (S. Han) and graduate students (P. Lu) as well as postdoctoral scholar (F. Jiang). Interactions with producers and scientists are active and on-going. TARGET AUDIENCES: Effort from his project has resulted in the development of efficient pathways to isolate major biomass components and their conversion into advanced nanomaterials with novel functional properties. Better understanding of the structure and isolation of biologically derived components has been gained from developing effective and robust chemical pathways and processes. This knowledge base offers opportunities for new biobased products and bionano materials as well as solutions to expanded value-added utilization of renewable resources. Potential audiences range from agricultural and forest product producers to food and beverage processing, industrial and consumer product sectors to biotechnology and biomedical industry. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
Pure cellulose has been isolated from white grape skins obtain in chardonnay wine making process at a 16.4% yield by a process involving organic extraction, acid and base dissolutions, and basic and acidic oxidation. The moderately crystalline (54.9% CrI) and microfibrillar grape skin cellulose was acid hydrolyzed (64-65% H2SO4 45 degree C, 30 min) into slightly more crystalline (64.3% CrI) and spherical cellulose nanocrystals (CNCs) with a mean diameter of 48.1 (+/- 14.6) nm by TEM that consisted of a nano-rod core (seed) surrounded by numerous tiny cellulose fragments by AFM. This is the first report of nanocellulose from grape skins. Highly pure amorphous silica has been derived from rice straw ash by a base dissolution and acid precipitation process at a 90.8% yield. Rice straw was heated at 10 degree C/min and held at 250, 325 and 575 degree C to facilitate decomposition and gasification of the organics while avoiding auto-ignition to silica. Base dispersion and neutralization of silica yielded gels that upon freeze-drying produced mesoporous silica powders with a 5.8 nm average pore size (2 to 22 nm pore size distribution) and very high specific surface (509.5 m2/g BET and 637.0 m2/g BJH) and pore volume (0.925 cm3/g). These silica powders were dispersible in water and shown to consist of nano-disks with an average 172 nm diameter and 3.09 nm thickness as measured by TEM and AFM, respectively.
Publications
- Lu, P. and Y.-L. Hsieh, Cellulose isolation and core-shell nanostructures of cellulose nanocrystals from chardonnay grape skins, Carbohydrate Polymers, 87:2546-2553 (2012).
- Lu, P. and Y.-L. Hsieh, Highly pure amorphous silica nano-disks from rice straw, Powder Technology, 225:149-155 (2012).
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Progress 01/01/11 to 12/31/11
Outputs
OUTPUTS: Cellulose nanofiber surfaces have been 1) chemically reacted to carry reactive moieties to serve as templates to support and strength hydrogel that swell to 62 times of mass; 2) electrostatically bound with alternating layers of polysaccharidic electrolytes. Cellulose nanocrystals have been derived from rice straw to exhibit self-assembling behavior. These cellulose based nanomaterials and nanofibers demonstrate viable strategies for utilizing polysaccharides to achieve novel functionality for advance material applications. Results of this project have been disseminated in professional conferences (e.g., American Chemical Society, the Fiber Society), with USDA scientists, agricultural sections (rice, wine) as well as presented in invited talks in California as well as exchanged internationally (China, Taiwan, Turkey). PARTICIPANTS: The project has provided research training experience in the areas of natural products and biomaterials for graduate and undergraduate students as well as postdoctoral scholars. Considerable interest from university colleagues and scientists in the private sectors including those in Canada, China and Taiwan has been expressed on the potential applications of novel fibrous materials derived from polysaccharides. TARGET AUDIENCES: The findings of this project have resulted in the conversion of polysaccharides and the creation of advanced nanomaterials with novel functional properties. Better understanding of the structure and isolation of biologically derived components has been gained from developing effective and robust chemical pathways and processes. This knowledge base offers opportunities for new biobased products and bionano materials as well as solutions to expanded value-added utilization of renewable resources. Potential audiences can ranged from agricultural and forest product producers to industrial and consumer product sectors to biotechnology and biomedical industry. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
Cellulose surfaces have been activated by chemical reaction and electrostatic bonding approaches. Reaction with di-aldehydes, i.e., polyethylene glycol (PEG) diacylchloride and glutaraldehyde (GA), yielded aldehyde moieties of Cell-PEG-COCl and Cell-CHO, respectively. Cellulose fibers and microcrystalline cellulose were readily esterified by PEG diacylchloride to form Cell-PEG-COCl to reach as high as 0.24 and 0.37 mmol aceylchloride per g cellulose, respectively. These surface aldehyde groups demonstrated robust reactivities to generate cellulose fiber supported hydrogels that could swell up to 62 times. Multiple bilayered polysaccharide biofilms have been assembled by electrostatic layer-by-layer (LBL), alternating deposition of cationic chitosan (CS, Mv=405 kDa) and anionic dextran sulfate (DXS, Mw=500 kDa) onto ultra-fine cellulose and partially hydrolyzed cellulose acetate fibers. Each CS/DXS bilayer averaged 6.4 to 9.0 nm thick with the total thickness of the five bilayer (CS/DXS)5 varied from 64 to 77 nm. The findings proofed the concept that long chain polysaccharide electrolytes can be self-assembled as nanometer scale tubular bilayers on ultra-fine cellulose fibers to afford wholly polysaccharidic fibrous architecture. The electrolytic nature, chemical reactivity and structural versatility of these ultra-high specific surface polysaccharides are advantageous and can be further tuned to serve biological functions and for biomedical applications. Pure cellulose have been isolated from rice straw at 36% yield and hydrolyzed (64% H2SO4, 8.75 mL/g, 45 degrees C) for 30 and 45 min to cellulose nanocrystals (CNCs), i.e., CNC30 and CNC45, respectively. CNC45 was smaller (11.2 nm wide, 5.06 nm thick and 117 nm long) than CNC30 (30.7 nm wide, 5.95 nm thick and 270 nm long). Freeze-drying of diluted CNC suspensions showed both assembled into long fibrous structures: ultra-fine fibers (~400 nm wide) from CNC45 and 1-2 um wide broad ribbons interspersed with CNC clusters from CNC30. The self-assembled fibers from CNC30 and CNC45 were highly crystalline (86.0% and 91.2%, respectively), essentially nonporous or macroporous structures and showed extraordinary structural stability, withstanding vigorous shaking and prolong stirring in water.
Publications
- Wang, Y. and Hsieh, Y.-L., 2010, Aldehyde functionalized cellulose support for hydrogels, Journal of Applied Polymer Science, 118: 2489-2495.
- Ding, B., Du, J. and Hsieh, Y.-L., 2011, Layer-by-layer self-assembled polysaccharide electrolytes on cellulose nanofiber, Journal Applied Polymer Science, 121: 2526-2534.
- Lu, P. and Hsieh, Y.-L., 2012, Preparation and characterization of cellulose nanocrystals from rice straw, Carbohydrate Polymers, 87:564-573.
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Progress 01/01/10 to 12/31/10
Outputs
OUTPUTS: Natural polymers have been chemically isolated, converted and modified to form biological precursors to enabling the fabrication of nanomaterials and nanofibers. These results demonstrate viable strategies for utilizing polysaccharides to achieve novel functionality for advance material applications. Results of this project have been disseminated in professional conferences (e.g., American Chemical Society, the Fiber Society), with USDA scientists, agricultural sections (rice, wine) as well as presented in invited talks in thematic conferences in California as well as internationally (China, Turkey). PARTICIPANTS: The project has provided natural products and biomaterials research training for graduate and undergraduate students as well as postdoctoral scholars. Considerable interest from university colleagues and scientists in the private sectors including those in Canada, Scandinavia and China has been expressed on the potential applications of novel fibrous materials derived from polysaccharides. TARGET AUDIENCES: The findings of this project have resulted in the conversion of polysaccharides and the creation of advanced nanomaterials with novel functional properties. Better understanding of the structure and isolation of biologically derived components has been gained from developing effective and robust chemical pathways and processes. This knowledge base offers opportunities for new biobased products and bionano materials as well as solutions to expanded value-added utilization of renewable resources. Potential audiences can ranged from agricultural and forest product producers to industrial and consumer product sectors to biotechnology and biomedical industry. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
Cellulose nanocrystals (CNCs) with rod, sphere, and network morphologies were prepared by acid hydrolysis of cotton cellulose, followed by freeze-drying. Hydrolysis with sulfuric acid introduced sulfate groups to these nanocrystal surfaces permitting their dispersion in aqueous as well as organic media, including ethanol and N,N-dimethylformamide, in a matter of seconds. Freeze-drying, on the other hand, induced mesoporosity (91.99 + or - 2.57 Angstrom average pore width) and significantly improved specific surface (13.362 m2/g) that is about 9 times of the original cellulose (1.547 sq. m/g). Moreover, the nanocrystals exhibited improved thermal conductivity and considerably higher (nearly 30%) carbonaceous residue, possibly due to direct solid-to-gas decomposition. These results demonstrated that a combination of surface charge introduction and fixation of mesoporosity in cellulose nanocrystals is an efficient route to prepare large quantity of high quality cellulose nanocrystals with quick re-dispersion capability for practical applications. These CNCs have shown to improve the formation of polyacrylic acid (PAA) nanofibers and significantly improve their Young's modulus and stress by up to 35-fold and 16-fold, respectively. Heat-induced esterification between the CNC surface hydroxyls and PAA carboxyl groups produced covalent crosslinks at the CNC-PAA interfaces, rendering the nanocomposite fibrous membranes insoluble in water, more thermally stable and far more superior in tensile strength. With 20% CNC, the crosslinked nanocomposite fibrous membrane exhibited very impressive 77-fold increase in modulus and 58-fold increase in stress. The dissolution behavior of cellulose as well as asssse,bling surface nanofilms on cellulose nanofibrous membranes for enzyme binding have been studied. Cellulose nanofibers have also been significantly strengthened by loading with multi-walled carbon nanotubes (MWCNTs) at minute levels of 0.11 and 0.55w%. The fact that MWCNTs were observed in only about a third of the fibers at a very low 0.55wt% loading suggests significantly higher tensile strength may be achieved by further increase in MWCNT loadings. The bi-phasial flow into cellulose nanofibrous webs has been modeled and related the porous medium parameters with the geometrical-structural properties of the material using a combination between the simple Lucas-Washburn equation for wicking dynamics and a Kozeny-Carman equation for permeability.
Publications
- Lu, P. and Y.-L. Hsieh, 2009, Cellulose nanocrystal filled poly(acrylic acid) nanocomposite fibrous membranes, Nanotechnology 20: 415604-415612.
- Lu, P. and Y.-L. Hsieh, 2010, Layer-by-layer self assembly of Cibacron Blue F3GA and lipase on ultra-fine cellulose fibrous membrane, Journal of Membrane Science, 348 (1-2):21-27.
- Zhang, S., F.-X. Li, J.-Y. Yu, Y.-L. Hsieh, 2010, Dissolution behavior and solubility of cellulose in NaOH complext solution, Carbohydrate Polymers, 81(3): 668-674.
- Lu, P. and Y.-L. Hsieh, 2010, Preparation and properties of cellulose nanocrystals: rods, spheres, and network, Carbohydrate Polymers, 82:329-336.
- Lu, P., Y.-L. Hsieh, 2010, Multi-Walled Carbon Nanotube (MWCNT) Reinforced Cellulose Fibers by Electrospinning, ACS Applied Materials & Interfaces, 2(8), 2413-2420.
- G. Callegari, I. Tyomkin, K.G. Kornev, A.V. Neimark, Y.-L. Hsieh, 2010, Absorption and transport properties of ultra-fine cellulose webs, Journal of Colloid and Interface Science, 353(1):290-293.
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Progress 01/01/09 to 12/31/09
Outputs
OUTPUTS: This project aims to study the structure of natural polymers and to investigate chemical means to create new materials and fibrous products from natural sources. Structural elucidation of natural polymers and fibers using advanced analytical methodologies gives fundamental understanding of how nature synthesizes and organizes polymers such as cellulose and proteins the native structures. PARTICIPANTS: This project has provided materials research training in the areas of natural products and functional fibers for two undergraduate students, two graduate students and one postdoctoral researcher. Considerable interest from university colleagues and scientists in the private sectors including those in Canada, Scandinavia and China has been expressed on the potential applications of novel fibrous materials derived from polysaccharides. TARGET AUDIENCES: The findings of this project thus far have shown effective and robust chemical pathways and processing parameters to generate new fibrous materials from polysaccharides, specifically cellulose, chitin, chitosan and their derivatives. This knowledge base offers opportunities for new biobased materials and products as well as solutions to expanded value-added utilization of renewable resources. Potential audiences can range from agricultural and forest product producers to industrial and consumer product sectors to biotechnology and biomedical industry. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
Natural polymers have been chemically modified to synthesize from biological precursors to enabling fiber processing and to achieve functional properties, including hybrid polysaccharide nanofibers, nanofiber-bound catalysts (enzymes) and enzyme encapsulation via aqueous and organic compatible nanoporous fibers. These results demonstrate viable strategies for utilizing polysaccharides to achieve novel functionality for advance material applications. Results of this study have been disseminated in professional conferences (e.g., American Chemical Society, the Fiber Society) as well as presented in invited talks in thematic conferences in California as well as internationally (European Polysaccharide Network of Excellence (EPNOE)).
Publications
- Du, J. and Y.-L. Hsieh, (2009), Cellulose-chitosan nanofibers from electrospinning of their ester derivatives, Cellulose, 16(2): 247-260. Lu, P. and Y.-L. Hsieh, (2009), Lipase Adsorption to Cellulose Nanofibrous Membrane via Cibacron Blue F3GA as the affinity ligand, Journal of Membrane Science, 330: 288-296.
- Lu, P and Y.-L. Hsieh, (2009), Organic compatible polyacrylamide hydrogel fibers, Polymer 50: 3690-3679.
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Progress 01/01/08 to 12/31/08
Outputs
OUTPUTS: The non-thermoplastic nature and insolubility in organic solvents have made the nature's most abundant polysaccharides, i.e., cellulose and chitin, challenging to process and utilize as materials. We have been taking chemical approaches to reduce the molecular chain length as well as hydrogen bonding capacity to render cellulose and chitin soluble in various organic solvents and even water to be processed into fibers of unique structures and morphology. A robust process involving electrospinning cellulose esters followed by alkaline hydrolysis has been developed to produce cellulose nanofibers. Other new structures have included nanoporous and sheath-core cellulose nanofibers. Progress has been made to successfully incorporate beta-cyclodextrin (beta-CD) into cellulose at up to 50wt% content and spun into nanofibers with 2-nm nanopores and significantly increased specific surface and pore volume. In addition to previous success on aminated and acylated chitosan (CS), i.e., PEG-N-CS and PEG-N,O-CS, to generate both organic and water soluble derivatives and to electropspun into nanofibers, a more robust carboxylation reaction was also developed. Carboxymethylated chitosan (CMCS) at varied chitosan (CS) chain length (viscosity molecular weight = 40 - 405 kDa) and DS (0.25 - 1.19) has shown both C2 and C6 substitution at ambient temperature (N,O-carboxymethylated) and mainly C6 substitution at the lower -15 degrees C (O-carboxymethylated). Water solubility was achieved with 405 kDa CS at DS greater than or equal to 0.73 whereas the 40 and 89 kDa became water soluble at lower DS of 0.25 and 0.36, respectively. Electrospinning of aqueous solutions of CMCS was facilitated with the addition of water-soluble polymers, including PEO, PAA, PAAm and PVA. The fibrous membranes generated with less substituted CMCS were more hydrophilic and retained greater extent of the desirable amine functionality. PARTICIPANTS: This project has provided advanced research training in the natural products and functional fibers areas for three graduate students and two postdoctoral researchers have participated on some aspects of this project. Considerable interest from university colleagues and scientists in the private sectors has been expressed on the potential applications of novel fibrous materials derived from polysaccharides. TARGET AUDIENCES: The findings of this project thus far have shown effective and robust chemical and processing pathways to generate new fibrous materials from the major polysaccharides. This knowledge base offers opportunities for new biobased materials and products as well as solutions to better and value-added utilization of renewable resources. Potential audiences can range from agricultural and forest product producers to industrial and consumer product sectors to biotechnology and biomedical industry. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
This project aims to understand the structure of natural fibers and polymers and to investigate chemical means to create new materials and fibrous products from natural sources. Structural elucidation of cellulosic and other natural fibers using advanced analytical methodologies gives fundamental understanding of how nature synthesizes and organizes cellulose and proteins in the fibrous structures. Polymers have been synthesized from chemical reactions of biological precursors, such as polysaccharides, and characterized for potential functional properties, including ultra-high specific surface nanofibers and nanoporous fibers.
Publications
- Zhang, L. and Y.-L. Hsieh, (2008). Cellulose Acetate Based Ultrafine Bicomponent Fibers with Nanoscale Structural Features, Journal of Nanoscience and Nanotechnology, 8: 4461-4469.
- Du, J. and Y.-L. Hsieh, (2008). Nanofibrorus membranes from aqueous electrospinning of carboxymethyl chitosan, Nanotechnology, 19: 571-579.
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Progress 01/01/07 to 12/31/07
Outputs
Cellulose and chitin, nature's most abundant polysaccharides, are challenging to process due to their non-thermoplastic nature and difficulty in dissolving in organic solvents. These characteristics are due to their over 1 million Dalton molecular weight, rigid saccharidic ring and highly hydrogen bonded structure. In this project, significant progress has been made in creating cellulose and chitosan nanofibers through novel chemical and processing strategies. Difficulty in dissolving cellulose was overcome by processing cellulose ester derivatives into nanofibers followed by alkaline hydrolysis to cellulose. Sheath-core nanofibers and nanoporous cellulose fibers have been demonstrated by several chemical and processing strategies. Chitosan has been reductive aminated and acylated into PEG-N-chitosan and PEG-N,O-chitosan, respectively, to various degree of substitution (DS) and with varied PEG chain length. Water solubility were easily achieved by either reaction at DS
as low as 0.2 whereas the PEG-N,O-chitosan at DS=1.5 was soluble in organic solvents, such as CHCl3, DMF, DMSO and THF. Ultra-fine fibers with diameters ranging from 40-360 nm and an average diameter of 162 nm were electrospun from 15% PEG550-N,O-chitosan145 in 75/25 (v/v) THF/DMF cosolvents with 0.5% Triton X-100(trademarked).
Impacts
This project aims to understand the structure of natural fibers and polymers and to investigate chemical means to create new materials and fibrous products from natural sources. Structural elucidation of cotton and other natural fibers using advanced analytical methodologies gives fundamental understanding of how nature synthesizes and organizes cellulose and proteins in the fibrous structures. Polymers have been synthesized from chemical reactions of biological precursors, such as polysaccharides, and characterized for potential functional properties, including ultra-high specific surface nanofibers.
Publications
- Zhang, L. and Y.-L. Hsieh, Ultra-fine cellulose acetate/poly(ethylene oxide) bicomponent fibers, Carbohydrate Polymers, 71:196-207 (2007).
- Du, J. and Y.-L. Hsieh, PEGylation of chitosan for improved solubility and fiber formation via electrospinning, Cellulose (online June 2007).
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Progress 01/01/06 to 12/31/06
Outputs
This project aims to understand the structure of natural fibers and to investigate novel approaches to create new fibers and polymers from natural sources. Chemical processes have been devised to convert chitin and chitosan to water and organic soluble forms, enabling processing into fibers and for coating. Nanofiber and nanoporous fibers have been generated from polysaccharides (cellulose, chitin, and their derivatives). Natural products such as plant oil and fugal proteins have been developed into potential surface modifiers for improved water resistant materials.
Impacts
This project generates new understanding of natural fibers and builds new functional fibers and nanoscale materials from natural products. Novel fibrous materials have been generated from natural polymers such as proteins (including enzymes) and polysaccharides (including cellulose derivatives). Fibers with diameters between 100 nm and 1 micrometer have been formed with wide ranging inter- and intra-fiber porosity. Findings from this work have long-term implications on high value-added applications of biological components and materials.
Publications
- Li L. and Y.-L. Hsieh, 2005, Ultra-fine Polyelectrolyte Hydrogel Fibers from Poly(acrylic acid)/Poly(vinyl alcohol), Nanotechnology 16: 2852-2860.
- Li L. and Y.-L. Hsieh, 2006, Chitosan nanofibers and nano-porous fibers, Carbohydrate Research, 341: 374-381.
- Zhang, L. and Y.-L. Hsieh, 2006, Nanoporous ultrahigh specific surface polyacrylonitrile fiber, Nanotechnology, 17: 1-8.
- S. Gordon and Y.-L Hsieh, 2006, Cotton Science and Technology, Eds, Woodhead Publishing Ltd, Cambridge UK.
- Y.-L. Hsieh, 2006, Chemical Structure of Cotton fibers, in Cotton Science and Technology, S. Gordon and Y.-L. Hsieh, Eds, Woodhead Publishing Ltd, Cambridge UK.
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Progress 01/01/05 to 12/31/05
Outputs
This project aims to understand the structure of natural fibers and to investigate chemical means to create new fibrous products and polymers from natural sources. New polymers and fibrous products have been synthesized from biological precursors, converted to ultra-fine fibers via electrospinning and characterized for functional properties. Nanofibers have been generated from polysaccharides (cellulose, chitin, and their derivatives). Ultra-fine hydrogel fibers have been created with super-absorbent and volume expansion capacities. The mass and volume swellings can be regulated by changing chemistries as well as fiber/pore configurations. These behaviors are stimuli-responsive, i.e., triggered by pH, temperature or electric fields.
Impacts
Novel fibrous materials have been generated from natural and biobased polymers such as proteins (including enzymes) and polysaccharides (including cellulose derivatives). Fibers with diameters between 100 nm and 1 m have been formed with wide ranging inter-fiber porosity. Research has shown promise of nanoporous structure inside fibers, a basis for nano- and biobased materials science from agricultural components and materials. Research in this area helps to build basis for nano-materials science and has long term implications on high value-added applications of agricultural components and materials.
Publications
- Chen, H. and Hsieh, Y.-L. 2004. Ultra-fine hydrogel fibers with dual temperature- and pH-responsive swelling behaviors, Journal of Polymer Science, Polymer Chemistry 42:6331-6339.
- Chen, H. and Hsieh, Y.-L. 2005. Enzyme immobolization on ultra-fine cellulose fibers via poly(acrylic acid) electrolyte grafts, Biotechnology and Bioengineering 90(4):405-413.
- Li, L. and Hsieh, Y.-L. 2005. Ultra-fine polyelectrolyte fibers from electrospinning of poly(acrylic acid). Polymer 46(14):5133-5139.
- Jin, X. and Hsieh, Y.-L. 2005. pH-responsive swelling behaviors of poly(vinyl alcohol)/poly(acrylic acid) bi-component fibrous hydrogel membranes. Polymer 46(14):5149-5160.
- Jin, X. and Hsieh, Y.-L. 2005. Anisotropic dimensional swelling of membranes of ultra-fine hydrogel fibers. Macromolecular Chemistry and Physics 206(17):1752-1756.
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Progress 01/01/04 to 12/31/04
Outputs
This project has embarked on the study of transgenic modification on cotton fiber quality and formation of functional fibers via electrospinning. The declining quality and quantity of domestic cotton production coinciding with the introduction (1996) and increasing share (>70%) of genetically modified cultivars in the U.S. raises question on whether genetic modification to achieve herbecide and/or insect resistance affects fiber development, thus quality. This question is being addressed in a new multi-year research project by Hsieh's group. The strength and structural characterization of transgenic cottons have been studied on five transgenic cottons (Stoneville 474, 4793R, 4691B, 4892BR, BXN 47) and examine fiber strength from field samples as well as those collected from greenhouse grown plants. The dyeing quality of cotton species, including three cultivars of cotton representing Gossypium hirsutum, G. arboreum, and G. barbadense and a reactive blue dye.
Exploration of electrospinning of several natural polymers have generated fibers with diameters in hundreds nanometers to less than 100 nm. These fibers have ultra-high specific surface and posses unique porous and fibrous structures. Efforts have been initiated to modify these ultra-high surface and nanoporous fibers.
Impacts
Our work on transgentic cotton fiber quality shows how fiber strength depends on cell development as well as cultivars and dyeing behavior varies among developmental stages as well as differences among species. Novel porous and ultra-fine fibrous materials have been created with natural and biobased polymers. Several chemical and physical strategies have been explored to generate ultra-high specific surface fibrous materials from natural and biobased polymers such as proteins (including enzymes) and polysaccharides (including cellulose derivatives). Fibers with diameters between 100 nm and 1 um have been formed with wide ranging inter-fiber porosity. Research has shown promise of nanoporous structure inside fibers, a basis for nano- and biobased materials science from agricultural components and materials. Research in this area helps to build basis for nano-materials science and has long term implications high value-added applications of agricultural components and
materials.
Publications
- Chen, H. and Y.-L. Hsieh. 2004. Dual temperature and pH-sensitive hydrogels from interpenetrating networks (IPN) and copolymerization of sodium acrylate and N-isopropylacrylatmide. Journal of Polymer Science, Polymer Chemistry 42:13:3239-3301.
- Wang, Y. and Y.-L. Hsieh. 2004. Enzyme immobilization to ultra-fine cellulose Fibers via amphiphilic polyethylene glycol (PEG) spacers, Journal of Polymer Science, Polymer Chemistry 42(16):4289-4299.
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Progress 01/01/03 to 12/31/03
Outputs
Effort has been focused on cotton fiber structure resulted from transgenic modification, chemical reactions on fiber surfaces and formation of ultrafine fibers. We have studied single fiber strength and structure related to transgentic alteration of five transgenic cottons (Stoneville 474, 4793R, 4691B, 4892BR, BXN 47). We have developed processes by which ultra-fine fibers were generated from electrospinning of natural and synthetic polymers, including cellulose and proteins. The focus has been on the formation of novel fibrous structures, such as nanoporosity, and their chemical modification. These fibers are ultra-fine and posses unique porous and fibrous structures with ultra-high surface-to-volume characteristics. Liquid wetting and absorption phenomena have been studied in relationship to their chemistry and morphology.
Impacts
Single fiber strength of transgentic cotton depends on cell development as well as cultivars. Several chemical and physical strategies have been explored to generate ultra-high specific surface fibrous materials from natural and biobased polymers. Fibers with diameters between 100 nm and 1 m have been formed with wide ranging inter-fiber porosity. Research has shown promise of nanoporous structure inside fibers, a basis for nano- and biobased materials science from agricultural components and materials.
Publications
- XIE, J. and HSIEH, Y.-L. 2003. Ultra-high surface fibrous membranes from electrospinning of natural proteins: casein and lipase enzymes, Symposium book, Journal of Material Science 38, 2125-2133.
- XIE, J. and HSIEH, Y.-L. 2002. Modification of cellulose solids by enzyme-catalyzed transesterification with vinyl esters in anhydrous organic solvents, in Biocatalysis in Polymer Science, American Chemical Society Symposium Series 840, Pages 217-230.
- LIU, H. and HSIEH, Y.-L. 2003. Surface methacrylation and graft-co-polymerization of ultra-fine cellulose fibers, Journal of Polymer Science, Polymer Physics (41):953-964.
- HSIEH, Y.-L., HARTZELL-LAWSON, M.M., BOSTON, M.G., CLARKSON, K.A., COLLIER, K.D., and GRAYCAR, T.P. August 20, 2002. Enzyme treatment to enhance wettability and absorbency of textiles, U.S. Patent No.6,436,696.
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Progress 01/01/02 to 12/31/02
Outputs
This project has continued on two aspects of research during 2002. They are studies of transgenic modification on cotton fiber quality and processing and chemical reactions of functional fibers. This the second year in which we study cotton fiber quality as related to effects of transgentic alteration. We have selected five transgenic cottons (Stoneville 474, 4793R, 4691B, 4892BR, BXN 47) and examine fiber strength from field samples as well as those collected from greenhouse grown plants. We have developed processes by which ultra-fine fibers were generated from electrospinning of polymer solutions of natural and synthetic sources. The focus has been on the formation of novel fibrous structures and their modification. These fibers are ultra-fine and posses unique porous and fibrous structures with ultra-high surface-to-volume characteristics. In some cases, liquid wetting and absorption phenomena have been studied in relationship to their chemistry and morphology.
Impacts
Our work on transgenic cotton fiber quality shows how fiber strength depends on cell development as well as cultivars. Novel porous and ultra-fine fibrous materials have been created with natural and biobased polymers. Research in this area helps to build basis for nano-materials science and has long term implications high value-added applications of agricultural components and materials.
Publications
- Liu, J.-H., Yang, H. and Hsieh, Y.-L. 2001. Variations of mature cotton fiber tensile properties: Association with seed position and fiber length. Textile Res. J. 71(12):1079-1086.
- Fan, X.-D., Hsieh, Y.-L., and Krochta, J. M. 2002. Thermal and mechanical behaviors of poly(vinyl alcohol)-lactose blends. J. of Appl. Polym. Sci. 83: 929-935.
- Schreuder-Gibson, H. L., Gibson, P. W. and Hsieh, Y.-L. 2002. Transport properties of electrospun nonwoven membranes. Int'l. Nonwovens J. 11(2):21.
- Liu, H. and Hsieh, Y.-L. 2002. Ultrafine fibrous cellulose membranes from electrospinning of cellulose acetate. J. of Polym. Sci., Polym. Physics 40:2119-2129.
- Hsieh, Y.-L., Hartzell-Lawson, M. M., Boston, M. G., Clarkson, K. A., Collier, K. D. and Graycar, T. P. 2002. Enzyme treatment to enhance wettability and absorbency of textiles. U.S. Patent No.6,436,696 B1 (August 20, 2002)
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Progress 01/01/01 to 12/31/01
Outputs
This project has embarked on two new aspects of research during 2001. They are studies of transgenic modification on cotton fiber quality and electrospinning of functional fibers. The declining quality and quantity of domestic cotton production coinciding with the introduction (1996) and increasing share (>70%) of genetically modified cultivars in the U.S. raises question on whether genetic modification to achieve herbicide and/or insect resistance affects fiber development, thus quality. This question is being addressed in a new multi-year research project by Hsieh's group. The effort in the first year focuses on the establishment of sampling and measurement protocols. Exploration of electrospinning of several natural polymers have generated fibers in the hundreds nanometers of diameters. These fibers are ultra-fine and possess unique porous and fibrous structures with highest surface-to-volume characteristics. Work on cotton fiber quality also continues in the area
of dyeing quality of cotton species, employing three cultivars of cotton representing Gossypium hirsutum, G. arboreum, and G. barbadense and a reactive blue dye.
Impacts
Our work on cotton fiber quality shows that dyeing behavior varies among developmental stages as well as differences among species. Novel porous and fibrous materials have been created with natural and biobased polymers and have long term implications for high value-added applications.
Publications
- Hsieh, Y.-L., Hartzell-Lawson, M. M., Boston, M. G., Clarkson, K. A., Collier, K. D. and Graycar, T. P. 2000. Enzyme treatment to enhance wettability and absorbency of textiles, U.S. Patent No.6,0066,494 (May 23).
- Han, J. H., Krochta, J. M., Kurth, M. J. and Hsieh, Y.-L. 2000. Lactitol-based poly(ether polyol) hydrogels for controlled release chemical delivery systems. J. Agric. Food Chem. 48(11):5278-5282.
- Han, J. H., Krochta, J. M., Kurth, M. J. and Hsieh, Y.-L. 2000. Mechanism and characteristics of protein release from lactitol-based crosslinked hydrogel. J. Agric. Food Chem. 48(11):5658-5665.
- Ibbett, R.N. and Hsieh, Y.-L. 2001. The effects of fibre swelling on the structure of lyocell fabrics. Textile Res. J. 71(2):164-173.
- Hu, X.-P. and Hsieh, Y.-L. 2001. Effects of dehydration effects on the structure and tensile properties of developing Acala cotton fibers. Textile Res. J. 71(3):231-239.
- Hsieh, Y.-L. 2001. Surface characteristics of polyester fibers, in Surface Characteristics of Fibers and Textiles: Part III, Ed. C. Pastore pages 34-57.
- Lin, C.-H. and Hsieh, Y.-L. 2001. Direct scouring of greige cotton fabrics with proteases. Textile Res. J. 71(5):425-434.
- Zhou, W-.J., Hsieh, Y.-L., Pratt, L. M. and Patten, T. E. 2001. Experimental and computational studies of the bulk polymerization of styrene in the presence of POP and CHOP. Polymer Bulletin 46:43-50.
- Kim, C. and Hsieh, Y.-L. 2001. Wetting and absorbency of non-ionic surfactant solutions on cotton fabrics. Colloids and Surfaces 187-188:385-397.
- Jacobsen, K. R., Grossman, Y. L., Hsieh, Y.-L., Plant, R. E., Larlor, W. F. and Jernstedt, J. A. 2001. Neps, seed-coat fragment and non-seed impurities in processed cotton, dyeing characteristics of processed fibers. J. of Cotton Sci. 5(1):53-67.
- Xie, J. and Hsieh, Y.-L. 2001. Enzyme-catalyzed transesterification of vinyl esters on cellulose solids. J. of Polymer Sci., Polymer Chem. 39:1931-1939.
- Fan, X.-D., Hsieh, Y.-L., Krochta, J. M. and Kurth, M. J. 2001. Study on molecular interaction behavior, and thermal and mechanical properties of polyacrylic acid and lactose blends. J. of Applied Polymer Sci. 82(8):1921-1927.
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Progress 01/01/00 to 12/31/00
Outputs
This project has focused on studying the variations in cotton fibers and the chemical conversion of lactose and casein. The single fiber strength of greenhouse-grown developing and plant matured cotton fibers (G. hirsutum, Maxxa and Texas Marker 1) cotton fibers have been studied with respect to the location of fibers in the ball as well as along the length of the fibers. Fibers from the chalazal ends were narrowest and had lowest linear densities. The tenacities of single fibers from the medial regions of the ovules were higher than those from the chalazal and micropylar ends, with the latter two being similar. The forces required to break the middle sections of the fibers were higher than those to break fiber sections closer to the basal or the tip ends. Differences between G. hirsutum (Texas Marker 1) and G. barbedense (Pima S7) have been studied and compared. Structural characterization by wide-angle X-ray shows that neither crystallite dimensions nor
cyrstallinity change significantly beyond five weeks, consistent with the leveling of tenacities at this later stage of fiber development. Our work on the conversion of lactose and the synthesis of monomers and polymers containing lactose moieties has produced water-soluble polymers, amphiphilic polymers, super-absorbent hydrogels, and thermally-sensitive hydrogels. Complexing of the water-soluble lactose-containing polymers with borate can also generate hydrogels.
Impacts
Our work on cotton fiber quality contributes to our understanding on strength development during cell growth and on the relationship between fiber structure and properties. The work on lactose and casein contribute to better conversion and utilization of these natural biomaterials.
Publications
- Hsieh, Y.-L. 1999. Structural development of cotton fibers and linkages to fiber quality. Cotton Fibers, Ed. A.S. Basra, Food Products Press, New York, 137-165.
- Zhou, W.-J. , Kurth, M. J., Hsieh, Y.-L. and Krochta, J. M. 1999. Synthesis and thermal propeties of a novel lactose-containing poly(n-isopropylacrylamide-co-abrylamidolactamine) hydrogel. J. of Polym. Sci., Polym. Chem. 37:1393-1402.
- Hsieh, Y.-L. and Cram, L. 1999. Proteases as scouring agents for cotton. Text. Res. J. 69(8):590-597.
- Zhou, W.-J., Kurth, M. J., Hsieh, Y.-L. and Krochta, J. M. 1999. Synthesis and characterization of new styrene main-chain polymer with pendant lactose moiety through urea linkage. Macromolecule 32(17):5507-5513.
- Hsieh, Y.-L. and Wang, A. 2000. Single fiber strength variations of developing cotton fibers - among ovule locations and along fiber length. Text. Res. J. 70(6):495-501.
- Chacon, D., Hsieh, Y.-L., Kurth, M. J. and Krochta, J. M. 2000. Swelling and protein absorption/desorption of thermo-sensitive lactitol-based polyether polyol (LPEP) hydrogels. Polymer 41:8257-8262.
- Hsieh, Y.-L., Hu, X.-P. and Wang, A. 2000. Single fiber strength variations of developing cotton fibers - strength and structure of G. hirsutum and G. barbedense. Text. Res. J. 70(8):682-690.
- Dong, Q. and Hsieh, Y.-L. 2000. Acrylonitrile graft copolymerization of casein proteins for enhanced solubility and thermal properties. J. Appl. Polym. Sci. 77:2543-2551.
- Hartzell-Lawson, M. M. and Hsieh, Y.-L. 2000. Characteristics of noncellulosics in developing cotton fibers. Text. Res. J. 70(9):810-819.
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