Effect of Grafting Density on the Crystallization Behavior of Molecular Bottlebrushes,Macromolecules

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Effect of Grafting Density on the Crystallization Behavior of Molecular Bottlebrushes
Macromolecules ( IF 5.1 ) Pub Date : 2024-08-19 , DOI: 10.1021/acs.macromol.4c00752
Jeffrey T Wilk ₁ , Carl T Furner ₁ , Ethan W Kent ₂ , Michael T Kelly ₂ , Bin Zhao ₂ , Christopher Y Li ₁

Affiliation

A unique case of sterically constrained crystallization arises in bottlebrush polymers bearing semicrystalline side chains. Bottlebrushes with grafted side chains can form crystalline structures governed by the complex interplay between side chain packing and backbone confinement. The confinement effect can be readily tuned by varying the side chain grafting density, thus affording control over the crystallization behavior of these systems. In this work, the grafting density effect on the crystallization behavior of molecular bottlebrushes comprising poly(ethylene oxide) (PEO) side chains grafted to a methacrylate backbone was systematically studied. Thermal analysis using differential scanning calorimetry showed that the bottlebrush polymers displayed suppressed crystallization temperatures, lower melting temperatures, and reduced crystallinities compared to linear homopolymer PEO. The crystalline morphology was investigated using polarized light, atomic force, and scanning electron microscopy. Isothermal crystallization experiments revealed a nonmonotonous dependence of the nucleation density on the side chain grafting density. The grafting density effect was also investigated using self-seeding experiments, revealing an increased clearing temperature and memory retention at higher grafting densities. This work highlights how grafting density influences the crystallization behavior of semicrystalline bottlebrushes, providing information for the processing and application of these unique polymers.

中文翻译：

接枝密度对分子瓶刷结晶行为的影响

带有半结晶侧链的洗瓶刷聚合物中出现了空间约束结晶的独特情况。具有接枝侧链的洗瓶刷可以形成由侧链堆积和主链限制之间复杂的相互作用控制的晶体结构。通过改变侧链接枝密度可以很容易地调节限制效应，从而控制这些系统的结晶行为。在这项工作中，系统地研究了接枝密度对包含接枝到甲基丙烯酸酯主链的聚环氧乙烷（PEO）侧链的分子瓶刷的结晶行为的影响。使用差示扫描量热法的热分析表明，与线性均聚物 PEO 相比，瓶刷聚合物表现出抑制的结晶温度、较低的熔融温度和降低的结晶度。使用偏振光、原子力和扫描电子显微镜研究晶体形态。等温结晶实验揭示了成核密度对侧链接枝密度的非单调依赖性。还使用自播种实验研究了接枝密度效应，揭示了较高接枝密度下清除温度和记忆保留的增加。这项工作强调了接枝密度如何影响半结晶瓶刷的结晶行为，为这些独特聚合物的加工和应用提供信息。

更新日期：2024-08-19

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