The synthesis of self-assembling ABC amphiphilic tri-block copolymers as potential vehicles to be utilized in drug delivery systems is described. The A and C end blocks were permanently hydrophilic and hydrophobic, composed of amine and azide functionalized polyethylene oxide and polypropylene oxide, respectively. The synthesis of end group-modified polymers was confirmed by NMR. The center B block consisted of a pH-responsive peptide (i.e. lysine or glutamate) synthesized using ring opening NCA polymerization initiated from the amine functionalized A block. The degree of polymerization was determined by NMR and GPC. Poly(lysine) and poly(glutamate) act as either hydrophobic or hydrophilic blocks depending on side chain ionization. The pH responsive nature of the center block provides a means by which a sudden change in hydrophilic fraction can be triggered using a pH stimulus. Various molecular weights of A and B blocks were synthesized in order to target a change in hydrophilic weight fraction, which would occur upon pH stimulus, resulting in the micelle to vesicle self-assembled morphology transition. These structures were analyzed using light scattering and TEM.

Synthesis, self-assembly and morphology transitions in linear and star polypeptide-based block copolymers

247th National Meeting (2014)

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