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Aggregation behavior of poly([gamma]-benzyl-L-glutamate)-b-polyisoprene-b-poly([gamma]-benzyl-L-glutamate) rod-coil-rod triblock copolymer in N,N-dimethylformamide

Solution property of poly([gamma]-benzyl-L-glutamate)-b-polyisoprene-b-poly([gamma]-benzyl-L-glutamate) (GIG copolymer) was studied by using dynamic light scattering and static light scattering for N,N-dimethylformamide (DMF) solution and DMF/toluene mixed solutions. GIG copolymer proved to aggregate in DMF and under DMF-rich condition, that is, high-polar region. The aggregate decreased in size, and completely disappeared under toluene-rich condition, that is, low-polar region. The correlation between solubility parameter and aggregate size of GIG copolymer in the DMF/toluene solution systems quantitatively demonstrated how strongly polarity caused by hydrogen bond made an impact on the aggregation behavior. Because the main driving force to the aggregation under DMF-rich condition originates with polyisoprene (PIP) blocks, the aggregate in DMF is considered to be a core-shell micelle consisting of flexible PIP core surrounded by rigid poly([gamma]-benzyl-L-glutamate) (PBLG) shell. The values of dimensionless parameter [rho], defined as the ratio of radius of gyration [lang]S2[rang]1/2 to hydrodynamic radius RH, revealed that a single chain of GIG copolymer had the form of rigid rod with flexibility, that is, once-broken rod, caused by the incorporation of a flexible PIP chain between two rigid PBLG rods in the DMF/toluene solution system. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1740-1748, 2010

Authors:   Yoichi Ogata, Kazuhiro Iso, Satoshi Kura, Toshiyuki Hayakawa, Yutaka Makita
Journal:   Journal of Polymer Science Part B: Polymer Physics
Year:   2010
Pages:   1740
DOI:   10.1002/polb.22039
Publication date:   25-Jun-2010
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