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Tailoring the Properties of a Shape-Memory Polyurethane via Nanocomposite Formation and Nucleation
Macromolecules ( IF 5.1 ) Pub Date : 2018-02-22 00:00:00 , DOI: 10.1021/acs.macromol.7b01728 Anuja Shirole 1 , Apiradee Nicharat 1 , Carlo U. Perotto 1 , Christoph Weder 1
Macromolecules ( IF 5.1 ) Pub Date : 2018-02-22 00:00:00 , DOI: 10.1021/acs.macromol.7b01728 Anuja Shirole 1 , Apiradee Nicharat 1 , Carlo U. Perotto 1 , Christoph Weder 1
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Thermoplastic polyurethanes (PUs) can display shape-memory (SM) characteristics if their microphase-separated structure, consisting of domains formed by hard blocks and soft segments, respectively, is complemented with the ability of the soft segments to partially crystallize, so that the third phase thus formed can serve as the switching element for the shape-memory effect. While property modifications of SMPUs usually require de novo synthesis, we show at the example of a commercially available poly(ester urethane) consisting of crystallizable poly(1,4-butylene adipate) soft/switching segments and hard segments composed of 4,4-methylenediphenyl diisocyanate and 1,4-butanediol that the thermomechanical properties can also be modified by formulating nanocomposites and/or influencing the crystallization of the soft/switching segments via the addition of a nucleating agent. The incorporation of cellulose nanocrystals (CNCs) by simple melt-mixing allowed increasing the tensile storage modulus from 150 MPa (neat polymer) to 572 MPa (15% w/w CNCs) while the shape fixity at a specific fixing temperature was increased from 47 to 75%. The temperature at which good fixity (>97%) could be rapidly achieved was increased from 10 to 25 °C upon addition of 1% w/w dodecanoic acid, which served to nucleate the poly(1,4-butylene adipate) crystallization.
中文翻译：
通过纳米复合物的形成和成核来调整形状记忆聚氨酯的性能
如果热塑性聚氨酯（PU）的微相分离结构（分别由硬嵌段和软链段形成的区域组成）与软链段的部分结晶能力相辅相成，则可以显示形状记忆（SM）特性。这样形成的第三相可以用作形状记忆效应的开关元件。虽然通常需要从头修改SMPU的属性合成过程中，我们以市售的聚酯（氨基甲酸酯）为例，该聚酯由可结晶的聚（1,4-己二酸丁二酯）软/转换链段和由4,4-亚甲基二苯基二异氰酸酯和1,4-丁二醇组成的硬链段组成，还可以通过配制纳米复合材料和/或通过添加成核剂影响软/转换链段的结晶来改变热机械性能。通过简单的熔融混合掺入纤维素纳米晶体（CNC）可使拉伸储能模量从150 MPa（纯聚合物）增加到572 MPa（15％w / w CNC），而特定定影温度下的形状固定性从47提高至75％。加入1％w / w的十二烷酸后，可快速达到良好固着性（> 97％）的温度从10°C升高至25°C，
更新日期：2018-02-22
中文翻译：
通过纳米复合物的形成和成核来调整形状记忆聚氨酯的性能
如果热塑性聚氨酯（PU）的微相分离结构（分别由硬嵌段和软链段形成的区域组成）与软链段的部分结晶能力相辅相成，则可以显示形状记忆（SM）特性。这样形成的第三相可以用作形状记忆效应的开关元件。虽然通常需要从头修改SMPU的属性合成过程中，我们以市售的聚酯（氨基甲酸酯）为例，该聚酯由可结晶的聚（1,4-己二酸丁二酯）软/转换链段和由4,4-亚甲基二苯基二异氰酸酯和1,4-丁二醇组成的硬链段组成，还可以通过配制纳米复合材料和/或通过添加成核剂影响软/转换链段的结晶来改变热机械性能。通过简单的熔融混合掺入纤维素纳米晶体（CNC）可使拉伸储能模量从150 MPa（纯聚合物）增加到572 MPa（15％w / w CNC），而特定定影温度下的形状固定性从47提高至75％。加入1％w / w的十二烷酸后，可快速达到良好固着性（> 97％）的温度从10°C升高至25°C，
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