Photoinscription of Chain Anisotropy into Polymer Networks

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• 作者：Yuan Meng ; Jeh-Chang Yang ; Christopher L. Lewis ; Jisu Jiang ; Mitchell Anthamatten
• 刊名：Macromolecules
• 出版年：2016
• 出版时间：December 13, 2016
• 年：2016
• 卷：49
• 期：23
• 页码：9100-9107
• 全文大小：485K
• ISSN：1520-5835

文摘

Fixing chain orientation within polymeric materials can impart anisotropic mechanical, optical, and electrical properties. Although macroscopic anisotropy in amorphous or liquid crystalline phases has been achieved by cross-linking or by thermoreversible bond shuffling under strain, these methods lack spatial and temporal resolution. Here, we demonstrate a method to controllably write chain anisotropy into polymer networks containing both permanent and light-sensitive bonds. While held under mechanical stress or strain, light initiates a cascade of addition–fragmentation chain transfer reactions, causing photosensitive functional groups to reshuffle, thereby stabilizing the deformed network. Photoinscription of chain anisotropy allows for simplified processing on fully cross-linked networks with spatial and temporal control over chain orientation, thus enabling a spectrum of anisotropic polymeric materials. As an example, we demonstrate how built-in anisotropy of a semicrystalline network encourages crystallization along a preferred direction, leading to fully reversible shape actuation.