Recipient Organization
STATE UNIV OF NEW YORK
(N/A)
SYRACUSE,NY 13210
Performing Department
Chemistry
Non Technical Summary
We are proposing to produce polycysteine keratin-like substitutes for petroleumbased crosslinking agents. Although these polycysteine crosslinkers will be used to crosslink traditional resin and coating materials, our long-term goal will be to produce a totally biobased polymer coating and resin system using these polycysteine crosslinkers and other biobased materials developed in the Nomura Research Group.Awarded Start Date: 1/1/14End Date: 4/15/16 (as of 6/17/16)Sponsor: NYS Energy Research and Development Authority
Animal Health Component
(N/A)
Research Effort Categories
Basic
100%
Applied
(N/A)
Developmental
(N/A)
Goals / Objectives
To produce polycysteine polymers as energy-saving substitutes for petroleum-based crosslinking agents in resins and coatings.
Project Methods
Task 1. Development of a"green" chemoenzymaticsynthetic route to produce polycysteine. We will develop a "green" chemoenzymatic method (Figure 2) to produce polycysteine polymers that does not require the use of organic solvents. To accomplish this, we plan to perform a chemoenzymatic synthesis using papa in (an enzyme found in papayas) as the catalyst. An outline of the method to produce the polycysteine is described below: Chemoenzymatic synthesis of po/ycysteine. Synthesis of polycysteine will be carried out in a manner similar to that previously reported by Baker and Numata (1). The papa in will be suspended in sterile· water in the amount of 300 mg/ml and the insoluble fraction will be removed by centrifugation at10,000 g for 5 minutes at 22°C. The supernatant will be lyophilized and stored at -20°C until further use.Polymerization of l-cysteine-ethyl ester (l-cys-Et) will be carried out in 1 molar sodium bicarbonatebuffered to pH 11.0. The final concentrations of pa pain and l-cys-Et will be adjusted to 50 mg/ml and0.7 molar, respectively. The reaction will be stirred at 40°C for 12 hours, at which point the polycysteinewill be purified by centrifugation at 10,000 g for 5 minutes at 22°C. The pellet will be washed with 2%v/V HCI followed by water, at which point it will be lyophilized and stored at -20°C until further use. Ifnecessary, the reactions will be kept anoxic using nitrogen or argon to prevent cysteine self crosslinking.All polycysteine polymers made in Tasks 1 and 2 will be assessed for purity and degree of polymerizationby NMR and MAlDl-TOF testing at SUNY-ESF Analytical and Technical Services.Task 2: Development of a chemical synthetic route to produce polycysteine.As outlined in Figure 3, a traditional synthetic route to produce polycysteine will be performed inparallel in order to compare yields and properties with the polymers produced in Task 1. Attachment of Fmoc-cys(Acm) to Wang resin. The Wang resin will be suspended in 15 ml of a 9:1 v/vCHC'2/DMF. Separately, 2 equivalents of Fmoc-cys(Acm) and an equivalent amount of 1-hydroxy-7-azabenzotriazole(HOAt) will be dissolved in a minimal amount of DMF. Once dissolved, this solution will beadded to the resin solution. To this solution, 1 equivalent of dicyclohexylcarboimide (DCC} will bedissolved, followed by 0.1 equivalent of 2,2-dimethylaminopyridine (DMAP). The mixture will be stirredat 22°C for 3 hours, at which point 2 equivalents (with respect to the resin) of acetic anhydride andpyridine will be added to the reaction flask and allowed an additional 30 minutes to react. The Fmoccys(Acm) loaded resin will be collected by filtration and rinsed with DMF, followed by DCM, and finallymethanol.Deprotection of Fmoc protecting group. The resin will be submerged in 20% piperidine in DMF andreacted for 30 minutes at 22°C to remove the Fmoc protecting group. The resin will be collected byfiltration, washed with DMF, followed by DCM.Coupling of Fmoc-cys(Acm). To the modified resin, an amount of Fmoc-cys(Acm) equal to the amino acidloading will be dissolved in a minimal volume of DMF, followed by an equivalent amount of HOAt,N,N,N',N'-Tetramethyl-O-(lH-benzotriazol-1-yl)uronium hexafluorophosphate, O-(Benzotriazol-1-yl)N,N,N',N'-tetramethyluronium hexafluorophosphate (HBTU), and 10 equivalents of N,Ndiisopropylethylamine(DIPEA). The mixture will be stirred for 2 hours at 22°C then filtered and washedwith DMF, followed by DCM.Cleavage of peptide from Wang resin. The resin will be suspended with 50% trifluoroacetic acid (TFA) inDCM for 2 hours to remove the peptide from the resin. The resin will then be filtered and washed withTFA. The filtrate will be collected and peptide precipitated by addition to 10 volumes of cold ether.Task 3: Assessment of polycysteine as a crosslinker for resins and coatingsOnce the polycysteine polymers have been developed as defined by the current biomimicry proposal,these polymers will be assessed for use in coating and resin applications. These experiments will bedone in conjunction Dr. Mark Driscoll at the UV/EB Technology Center and the Institute for SustainableMaterials and Manufacturing at SUNY-ESF and Dan Montoney from Rapid Cure. The energy andenvironmental benefits associated with UV /EB compared to traditional catalysts are clear. Use of UV orEB curing methods are rapid (seconds vs. minutes or hours for standard chemical curing) and offer achance to improve productivity of coating processes. In addition, we can avoid organic solvents andvoe emissions using these methods. Overall, it is anticipated that we will be able to save up to 90% ofthe energy costs by using a UV /EB cross linking method vs. a thermally initiated (elevated temperature)crosslinking method. In addition, these novel biobased and biodegradable crosslinkers have thepotential to replace petroleum-based crosslinkers.In conjunction with Rapid Cure and the UV /EB Technology Center at SUNY-ESF, we will do a sideby-side comparison of crosslinking with polycysteine and a petroleum-based crosslinker. The degree ofcrosslinking will be varied by varying the concentrations of crosslinking agent. All reactions will beperformed at the UV /EB Technology Center at SUNY-ESF (see attached letters of support).