Aperiodic 鈥淏ricks and Mortar鈥?Mesophase: a New Equilibrium State of Soft Matter and Application as a Stiff Thermoplastic Elastomer

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• 作者：Weichao Shi ; Andrew L. Hamilton ; Kris T. Delaney ; Glenn H. Fredrickson ; Edward J. Kramer ; Christos Ntaras ; Apostolos Avgeropoulos ; Nathaniel A. Lynd ; Quentin Demassieux ; Costantino Creton
• 刊名：Macromolecules
• 出版年：2015
• 出版时间：August 11, 2015
• 年：2015
• 卷：48
• 期：15
• 页码：5378-5384
• 全文大小：401K
• ISSN：1520-5835

文摘

A new thermodynamically stable, aperiodic 鈥渂ricks-and-mortar鈥?(B&M) cellular mesophase structure is reported in PS₁-b-(PI-b-PS₂)₃ miktoarm copolymer and PS homopolymer blends [PS₁, long polystyrene; PI, poly(isoprene); PS₂, short polystyrene], where PS comprises discrete hard 鈥渂ricks鈥?and PI the continuous soft 鈥渕ortar鈥? The mesophase is unique in its extreme domain volume fractions, its lack of positional order, and quasi-long-range orientational order. On the basis of this unusual mesophase structure, a series of PS-based thermoplastic elastomers are realized, combining rigidity from an exceptionally high content of discrete glassy PS domains (up to 82 wt %) and high extensibility with recoverable elasticity from a low content of continuous rubbery PI (down to 18 wt %). The new elastomers show sharp yielding behavior while maintaining good elasticity at large strains. Tensile-SAXS experiments reveal that voiding plays an important role for the mechanical behavior and voids can open/close reversibly with/without loading. Plastic deformation only results in a slight loss of recoverable elasticity.