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http://dx.doi.org/10.5012/bkcs.2007.28.5.795

Conformational Transition of Poly(γ-benzyl-L-glutamate)-Poly(ethylene glycol) Block Copolymers in Bulk  

Choi, Young-Wook (Department of Chemistry, Hanyang University)
Park, Young-Mi (Department of Chemistry, Hanyang University)
Choo, Jae-Bum (Department of Applied Chemistry, Hanyang University)
Cho, Chong-Su (School of Agricultural Biotechnology, Seoul National University)
Sohn, Dae-Won (Department of Chemistry, Hanyang University)
Publication Information
Bulletin of the Korean Chemical Society / v.28, no.5, 2007 , pp. 795-799 More about this Journal
Abstract
The bulk properties of poly(γ-benzyl-L-glutamate)-poly(ethylene glycol), PBLG-PEO, diblock copolymer were investigated. The helical transition from 7/2 to 13/5 for pure PBLG was at 120 oC while those of GE-1 and GE-2, which contain flexible PEO block 40 wt% and 60 wt% respectively, were shown at 135℃ on DSC experiments. FT-IR and XRD experiments were shown that the diblock copolymers maintained their α-helical structure in the temperature range between 25℃ and 175℃. Increasing relative size of coil part resulted in the increase of intermolecular packing distances. Due to well-maintained helical structure, lyotropic LC phases were observed for the PBLG-PEO block copolymer by the polarized optical microscope (POM). Especially, GE-3 copolymer, which has 12.5 wt% PEO contents, showed the smectic C phase. The competition of favorable aggregation energy between rod-rod and coil-coil, and unfavorable aggregation energy of rod-coil give rise to change the supramolecular structure in mixed solvent.
Keywords
Block copolymer; Rod-coil copolymer; PBLG-PEO; Smectic C phase; Aggregation energy;
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