Design of Soft and Strong Thermoplastic Elastomers Based on Nonlinear Block Copolymer Architectures Using Self-Consistent-Field Theory

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• 作者：Nathaniel A. Lynd ; Folusho T. Oyerokun ; Donal L. O’ ; Donoghue ; Dale L. Handlin ; Jr. ; Glenn H. Fredrickson
• 刊名：Macromolecules
• 出版年：2010
• 出版时间：April 13, 2010
• 年：2010
• 卷：43
• 期：7
• 页码：3479-3486
• 全文大小：931K
• 年卷期：v.43,no.7(April 13, 2010)
• ISSN：1520-5835

文摘

Thermoplastic elastomers (TPEs) that are soft at low extension yet strong at large extension are of great importance in a variety of technological applications. In ABA-triblock architectures, both the overall molecular weight and the composition of the glassy A-blocks correlate with TPE strength. The design space of current TPEs based on linear ABA triblock copolymers (e.g., polystyrene-b-polybutadiene-b-polystyrene) is restricted by the accessibility of the order−disorder transition temperature, limiting the molecular weight, and restricted by the maximum volume fraction for which glassy A-blocks will form discrete domains. Using self-consistent-field theory (SCFT), we designed in silico two new, nonlinear TPE architectures that significantly relax the composition restriction: radial (ABA′)_n and A(BA′)_n miktoarm star-block copolymers with chemically identical, but unequal, molecular weight A-blocks. Through a balance of end-block bidispersity, block extraction from the interface, and architectural asymmetry, these molecular architectures are able to stabilize phases with discrete A-rich domains at remarkably high overall A-monomer compositions (f_A). In some cases the maximum f_A achieved for phases with discrete A-rich domains surpasses twice that of conventional linear ABA TPEs.