Photoactive Thermoplastic Elastomers of Azobenzene-Containing Triblock Copolymers Prepared through Atom Transfer Radical Polymerization
Atom transfer radical polymerization (ATRP) was used to prepare a new series of ABA triblock copolymers that are photoactive thermoplastic elastomers. The samples synthesized have the same rubbery midblock of poly(n-butyl acrylate) (PnBA) but differ in the degree of polymerization of the end blocks...
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Published in | Macromolecules Vol. 37; no. 19; pp. 7097 - 7104 |
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Main Authors | , , , , |
Format | Journal Article |
Language | English |
Published |
Washington, DC
American Chemical Society
21.09.2004
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Subjects | |
Online Access | Get full text |
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Summary: | Atom transfer radical polymerization (ATRP) was used to prepare a new series of ABA triblock copolymers that are photoactive thermoplastic elastomers. The samples synthesized have the same rubbery midblock of poly(n-butyl acrylate) (PnBA) but differ in the degree of polymerization of the end blocks of a methacrylate-based azobenzene-containing side-chain liquid crystalline polymer (Azo-SCLCP). The coupling between elasticity, liquid crystallinity and photoactivity imparts interesting features to this type of thermoplastic elastomers. When the solution-cast film is stretched at T > T g of the Azo-SCLCP whose microdomains act as physical cross-links, in contrast to conventional thermoplastic elastomers (such as styrene−butadiene−styrene triblock copolymer) that lose the elasticity, liquid crystalline microdomains can support part of the elastic extension of PnBA chains and, in the same time, deform to result in a long-range orientation of azobenzene mesogens. The liquid crystal orientation is retained in the relaxed film at T < T g, which creates a thermoplastic elastomer whose glassy microdomains contain oriented azobenzene mesogens. Moreover, the reversible trans−cis photoisomerization of the azobenzene chromophore can be used to modulate the mechanically induced orientation. |
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ISSN: | 0024-9297 1520-5835 |
DOI: | 10.1021/ma048995j |