Construction and Properties of Hyperbranched Block Copolymer with Independently Adjustable Heterosubchains
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- 作者：Jinxian Yang ; Lianwei Li ; Zongyang Jing ; Xiaodong Ye ; Chi Wu
- 刊名：Macromolecules
- 出版年：2014
- 出版时间：December 9, 2014
- 年：2014
- 卷：47
- 期：23
- 页码：8437-8445
- 全文大小：706K
- ISSN：1520-5835
文摘
A trifunctional initiator with one alkyne, one hydroxyl, and one bromine group was used to construct Br-polystyrene-alkyne-poly(蔚-caprolactone)-OH (Br鈥揚S鈥撯墶鈥揚CL鈥揙H) diblock copolymer precursor with one terminal alkyne group located at the junction between the two blocks. Further bromination and azidation substitution of the precursor led to a seesaw-type macromonomer azide-polystyrene-alkyne-poly(蔚-caprolactone)-azide (N3鈥揚S鈥撯墶鈥揚CL鈥揘3). Subsequently, novel hyperbranched copolymers [HB-(PS-b-PCL)n] with independently adjustable PS and PCL branching subchains were prepared by 鈥渃lick鈥?chemistry. All of the linear precursors and hyperbranched copolymers were characterized by FT-IR, 1H NMR, and GPC with triple detectors in detail. It was found that such hyperbranched copolymers are self-similar objects; namely, their intrinsic viscosities ([畏]) are scaled to the weight-average molar masses (Mw) as [畏] 鈭?Mw谓, where 谓 = 0.45 卤 0.01 and 0.48 卤 0.01 for the longer and shorter PS block, respectively. Moreover, the study on the crystallization behavior of unfractionated and fractionated HB-(PS-b-PCL)n copolymers indicated both the crystal size and the degree of crystallinity decrease with the PS subchain length and the overall degree of polymerization, and the remaining oligomer and macromonomer components could facilitate the crystallization of the unfractionated sample. Finally, it was found that the degree of crystallinity decreases dramatically when the weight fraction of fractionated hyperbranched copolymer in macromonomer/hyperbranched copolymer blend films exceeds 鈭?7%, indicating that the uncrystallizable hyperbranched chains may impose some extra restriction on the crystallization of the macromonomer chains.