Synthesis and Characterization of Sequence-Controlled Semicrystalline Comb Copolymers: Influence of Primary Structure on Materials Properties

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• 作者：Sansanee Srichan ; Navaphun Kayunkid ; Laurence Oswald ; Bernard Lotz ; Jean-Fran莽ois Lutz
• 刊名：Macromolecules
• 出版年：2014
• 出版时间：March 11, 2014
• 年：2014
• 卷：47
• 期：5
• 页码：1570-1577
• 全文大小：453K
• 年卷期：v.47,no.5(March 11, 2014)
• ISSN：1520-5835

文摘

Sequence-controlled semicrystalline copolymers were prepared by nitroxide-mediated copolymerization of a large excess of octadecylstyrene with small amounts of functional N-substituted maleimides (i.e., N-(n-propyl)maleimide, N-benzylmaleimide, pentafluorophenyl 4-maleimidobenzoate, 4-(N-maleimido)azobenzene, N-(1-pyrenyl)maleimide, and N-(2-(amino-BOC)ethylene)maleimide). These copolymers were prepared in bulk at 110 掳C using the commercial alkoxyamine BlocBuilder MA as initiator and control agent. Time-controlled additions protocols were used to place the N-substituted maleimides at precise chain location along the poly(octadecylstyrene) backbones. Size exclusion chromatography and ¹H NMR studies indicated that well-defined copolymers with controlled monomer sequences, composition, chain length, and molecular weight distribution were formed in all cases. Although possessing an atactic backbone, these polymers exhibit a semicrystalline behavior. The electron diffraction method indicated that the octadecyl side chains form lamellar phases. Moreover, differential scanning calorimetry studies evidenced a melting temperature in the range 40鈥?5 掳C and a crystallization temperature around 30鈥?5 掳C. It was observed that melting is influenced by the composition and sequence distribution of the copolymers. Thus, small microstructural variations allow a precise control over order鈥揹isorder transitions.