星形嵌段结构增强脂肪族聚酯热塑性弹性体的力学性能《Macromolecules》

Enhanced Mechanical Properties of Aliphatic Polyester Thermoplastic Elastomers through Star Block Architectures

Stephanie Liffland and Marc A. Hillmyer*

Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455-0431, United States

Macromolecules 2021, 54, 20, 9327–9340

Publication Date: October 4, 2021

https://doi.org/10.1021/acs.macromol.1c01357

Abstract

A series of sustainable aliphatic polyester thermoplastic elastomers (APTPEs) consisting of multi-arm star polymers with arms of poly(l-lactide)-b-poly(γ-methyl-ε-caprolactone) were investigated and compared to analogous linear poly(l-lactide)-b-poly(γ-methyl-ε-caprolactone)-b-poly(l-lactide) triblock polymers. Linear analogues with comparable arm molar mass and comparable overall molar mass were synthesized to distinguish architectural and molar mass effects. Overall, the star block polymers significantly outperformed their linear analogues with respect to ultimate tensile strength and tensile toughness, exhibiting more pronounced strain hardening than corresponding linear APTPEs. The stars exhibited high ultimate tensile strengths (∼33 MPa) and large elongations at break (∼1400%), outperforming commercially relevant, petroleum-derived, and non-degradable styrenic TPEs. The star polymers also exhibited superior recovery characteristics during cyclic strain cycles and reduced stress relaxation compared to the linear APTPEs, highlighting the impact of architecture on improved TPE mechanical properties. Dynamic mechanical thermal analysis suggests that the star architecture increases the usage temperature range and does not negatively influence processability, an important feature for future applications. Overall, this work illustrates that simple and convenient changes in the macromolecular architecture in sustainable APTPEs result in materials with greatly enhanced mechanical properties. A comprehensive understanding of the relationship between polymer architecture and mechanical properties can be capitalized on to develop property-specific and industrially relevant sustainable materials.

SUBJECTS:

• Deformation,

• Materials,

• Star polymers,

• Stress,

• Tensile strength

摘要

研究了一系列由多臂星形聚合物组成的可持续脂肪族聚酯热塑性弹性体（APTPEs），其臂为聚(L-丙交酯)-b-聚(γ-甲基-ε-己内酯)，并与类似的线性聚(L-丙交酯)-b-聚(γ-甲基-ε-己内酯)-b-聚（l-丙交酯)三嵌段聚合物进行了比较。合成了具有可比臂摩尔质量和可比总摩尔质量的线性类似物，以区分结构和摩尔质量效应。总体而言，星形嵌段聚合物在极限拉伸强度和拉伸韧性方面显著优于其线性类似物，表现出比相应的线性APTPE更显著的应变硬化。恒星显示出很高的极限拉伸强度(∼33 MPa）和大的断裂伸长率(∼1400%），优于商业相关、石油衍生和不可降解的苯乙烯类TPE。与线性APTPE相比，星形聚合物在循环应变循环期间也表现出优异的恢复特性，并减少了应力松弛，突出了结构对改善TPE机械性能的影响。动态机械热分析表明，星形结构增加了使用温度范围，不会对加工性能产生负面影响，这是未来应用的一个重要特征。总的来说，这项工作表明，可持续APTPE中大分子结构的简单而方便的变化导致材料的机械性能大大增强。对聚合物结构和机械性能之间关系的全面理解可以用于开发特定性能和工业相关的可持续材料。