Sub-10 nm microphase separation of polymers is an important technology to create well-defined nanostructures in polymer materials and thin films for various applications. In this paper, we examined crystallization and microphase separation of amphiphilic random copolymers bearing hydrophilic poly(ethylene glycol) (PEG) or poly(propylene glycol) and hydrophobic octadecyl groups in the solid state. For this, we synthesized various amphiphilic crystalline random copolymers with different hydrophilic pendants, main chains, composition, monomer sequence, and molecular weight distribution via living or free radical copolymerization. Solid samples of the copolymers were analyzed by differential scanning calorimetry, X-ray diffractometry, and small angle X-ray scattering. From the systematic investigations, we found that, in spite of broad molecular weight distribution, a random copolyacrylate bearing hydroxyl terminal PEG chains and octadecyl groups induced crystallization of the octadecyl groups to form well-ordered lamellar structures with about 5 nm domain spacing. It should be noted that quite small lamellar structures are constructed by common random copolymers with broad molecular weight distribution that are easily obtained from free radical copolymerization. This sub-10 nm microphase separation system developed herein would bring innovation in creating functional polymer materials with precision nanostructures.

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用于亚10纳米微相分离的两亲性晶体无规共聚物的设计指南

聚合物的亚10纳米微相分离是一项重要技术，可在聚合物材料和薄膜中创建定义明确的纳米结构，以用于各种应用。在本文中，我们研究了带有亲水性聚乙二醇（PEG）或聚丙二醇和疏水性十八烷基的两亲无规共聚物的结晶和微相分离。对于这一点，我们合成了各种两亲性结晶无规共聚物与不同的亲水吊坠，主链，组成，单体序列，以及分子量分布通过活性或自由基共聚。通过差示扫描量热法，X射线衍射法和小角度X射线散射法分析共聚物的固体样品。从系统研究中，我们发现，尽管分子量分布较宽，但带有羟基末端PEG链和十八烷基的无规共聚丙烯酸酯会诱导十八烷基结晶，形成具有约5 nm结构域间距的有序层状结构。应当指出，很小的层状结构是由具有宽分子量分布的普通无规共聚物构成的，该共聚物很容易从自由基共聚中获得。本文开发的此亚10纳米微相分离系统将带来创新，创造出具有精密纳米结构的功能聚合物材料。