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Synthesis and characterization of polymers incorporating N-alkyl urea-peptoid sequences

Chen, Xiaoping
http://rave.ohiolink.edu/etdc/view?acc_num=ucin1382951885

Abstract Details

2013, PhD, University of Cincinnati, Arts and Sciences: Chemistry.
This dissertation is mainly based on the works of synthesis and characterization of polymer/N-alkyl urea peptoid hybrid materials. Polymers were synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization using thrithiocarbonate and dithiocarbonate chain transfer agents in controlled manner. Poly(N-alkyl urea peptoid) was synthesized via step growth polymerization using symmetric diamine and diisocyanate. N-Alkyl urea peptoid sequences up to sixmer were synthesized through three steps repetition cycles in good yields. Several different hybrid polymeric materials were explored combining the three different material synthetic strategies including polymer conjugates shown in chapter 2, molecular brushes shown in chapter 3, water soluble A-B-A triblock copolymer shown in chapter 4. Firstly, two well-defined statistical copolymers poly(styrene-co-3-azidopropyl methacrylate) and poly(3-O-methacryloyl-1,2:5,6-di-O-isopropylidene-D-glucofuranose -co-AzPMA) were synthesized by RAFT. An exemplary N-alkyl urea peptoid trimer was synthesized and conjugated to the two copolymers through the 'click' reaction of the azide pendent group of polymers with the complilanry alkene group at N-alkyl urea peptoid. The polymer conjugates were subjected to further post-modification to generated fluorescent conjugates or water soluble materials. Following the explore of conjugation, N-alkyl urea peptoid was used as comonomer to synthesize linear poly(N-alkyl urea peptoid). The RAFT agent was introduced onto the linear polymer generated by step growth polymerization once again through 'click' reaction. Sequentially, styrene and tert-butyl acrylate was grown from RAFT agents sites that fused onto the poly(N-alkyl urea peptoid) backbone to make block copolymer arms. Upon removal of the tert-butyl groups, the molecular brushes were observed to generate micelles in aqueous solution. The self-assembly N-alkyl urea peptoid was then investigated and conjugated to water soluble polymer poly(ethylene glycol) to produce a A-B-A block copolymer that self-assembled into ribbons in aqueous solution. The final two part of dissertation was about gelling materials studies starting with presenting a synthesis strategy for low molecular weight organogelators (LMOG) using the ureidopyrimidinone (UPy) group functioned N-alkyl urea peptoid. The surprising observation of gelation in DMSO led to extensive investigation of the gelification mechanism studies. Based on the lessons of LMOG, the copolymerization of different Tg monomers with quadruple hydrogen bonding containing methacrylate was demonstrated suitable to produce polymeric organogelators in the final chapter.
Neil Ayres, Ph.D. (Committee Chair)
Edward Merino, Ph.D. (Committee Member)
David Smithrud, Ph.D. (Committee Member)
190 p.
Polymers
RAFT Polymerization; N-Alkyl Urea Peptoid; Polymer Conjugate; Polymeric Organogelators; Molecular Brushes

Recommended Citations

Citations

  • Chen, X. (2013). Synthesis and characterization of polymers incorporating N-alkyl urea-peptoid sequences [Doctoral dissertation, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1382951885

    APA Style (7th edition)

  • Chen, Xiaoping. Synthesis and characterization of polymers incorporating N-alkyl urea-peptoid sequences. 2013. University of Cincinnati, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1382951885.

    MLA Style (8th edition)

  • Chen, Xiaoping. "Synthesis and characterization of polymers incorporating N-alkyl urea-peptoid sequences." Doctoral dissertation, University of Cincinnati, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1382951885

    Chicago Manual of Style (17th edition)

ucin1382951885
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This open access ETD is published by University of Cincinnati and OhioLINK.