Hierarchically Ordered ABA Triblock Copolymer with Large Difference in Glass Transition Temperatures of the Two Blocks

Rod-coil-rod triblock copolymers, poly[4-(methoxy)-2-vinylbiphenyl-4-methyl ether] -blockpolydimethylsiloxane-block-poly[4-(methoxy)-2-vinylbiphenyl-4-methyl ether] (PMVBP-b-PDMS-b-PMVBP), were synthesized by nitroxide-mediated radical polymerization, and their hierarchically ordered structures were studied. A difunctional TEMPO macroinitiator was first synthesized by the hydrosilylation reaction between hydride-endcapped PDMS and allylic alkoxyamine. The polymerization of the monomer MVBP was triggered by the macroinitiator, resulting in a series of triblock copolymers. The molecular weights and polydispersity indexes were determined by gel permeation chromatography. Differential scanning calorimetry results demonstrate that the triblock copolymers exhibit two glass transition temperatures (-120 degrees C and 160 degrees C) that are markedly different. As revealed by small-angle X-ray scattering and transmission electron microscopy experiments, the triblock copolymers self-assemble into hierarchical structures with the liquid crystalline phase of PMVBP in the lamellar structures. (c) 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 1737-1744http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000335371100013&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=8e1609b174ce4e31116a60747a720701Polymer ScienceSCI(E)EI3ARTICLEchaicp@bit.edu.cn; fanxh@pku.edu.cn121737-17445