SELF-ASSEMBLY AND THE ASSOCIATED DYNAMICS IN PBLG-PEG-PBLG TRIBLOCK COPOLYMERS

摘要

Peptides of polyfy-benzyl-L-glutamate) (PBLG) are known to form two secondary structures: a-helices stabilized by intra-molecular hydrogen bonds and (3-sheets stabilized by inter-molecular hydrogen bonds [1][2]. The a-helical structure, in particular, is thought to give rise to a rigid rod structure and PBLG is used as a model rigid-rod polymeric system. In the present report we review our recent work on (i) the structure and dynamics of BLG oligopeptides [3], (ii) the hierarchical self-assembly of poly(Y-benzyl-L-gIutamate)-poly(ethylene glycol)-poly(Y-benzyl-L-glutamate) (PBLG-PEG-PBLG) triblock copolymers [4], and (iii) provide new results on the effect of interfacial mixing on the dynamics in the same triblock copolymers. We find that (i) the helical structures have low persistence length caused by structural defects, (ii) the incorporation of PEG next to the peptide blocks provides the means of controlling the stability of a specific peptide secondary structure. The latter has consequences on the local/segmental dynamics investigated by dielectric spectroscopy.