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首页> 外文期刊>e-Polymers >Synthesis and characteristics of novel azo-based diblock copolymers and their self-assembly behavior via solvents and thermal annealing
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Synthesis and characteristics of novel azo-based diblock copolymers and their self-assembly behavior via solvents and thermal annealing

机译：新型偶氮基二嵌段共聚物的合成，特征及其通过溶剂和热退火的自组装行为

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摘要

A series of azo-based diblock copolymers (DBCs) with various compositions were successfully synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization in anisole with PCAEMA-CTA (macro-CTA), DOPAM (new acrylamide monomer) and AIBN (initiator). Kinetic studies on diblock copolymerization manifested a controlled/living manner with good molecular weight control. Structures and properties of monomers and DBCs were determined by 1H nuclear magnetic resonance (NMR), differential scanning calorimetry (DSC) and gel permeation chromatography (GPC). Liquid crystalline (LC) phases and morphological properties were investigated using optical polarizing microscope (OPM), atomic force microscopy (AFM), scanning electron microscopy (SEM) and small-angle X-ray scattering (SAXS). Experimental results demonstrated that the prepared PCAEMA-CTA and DBCs possessed low polydispersity index (≤1.37). All DBCs revealed sharp endothermic transition peaks corresponding to the smectic-to-nematic phase. DBCs with high azo contents showed batonnet textures of the smectic phase whereas DBCs of low azo segments displayed threaded textures of the nematic phase. DBC with 49 wt% of azo side-chains generated a lamellar compared to DBCs with low azo block (≤41 wt%) or non-azo block (≤38 wt%) which produced hexagonal-type nanostructures. In addition, all DBCs exhibited reversible trans-cis photoisomerization behavior under UV irradiation and dark storage at different intervals of time.
机译：通过在苯甲醚中与PCAEMA-CTA（macro-CTA），DOPAM（新丙烯酰胺单体）和AIBN（引发剂）在苯甲醚中进行可逆加成-断裂链转移（RAFT）聚合，成功合成了一系列具有各种组成的偶氮基二嵌段共聚物（DBC）。 ）。对二嵌段共聚的动力学研究表明其具有良好的控制分子量的控制/活性方式。通过1 H核磁共振（NMR），差示扫描量热法（DSC）和凝胶渗透色谱法（GPC）确定单体和DBC的结构和性质。使用光学偏光显微镜（OPM），原子力显微镜（AFM），扫描电子显微镜（SEM）和小角X射线散射（SAXS）研究了液晶（LC）相和形态特性。实验结果表明，所制备的PCAEMA-CTA和DBC具有较低的多分散指数（≤1.37）。所有DBC都显示出与近晶相向向列相对应的尖峰吸热跃迁峰。偶氮含量高的DBC表现出近晶相的警戒质构，而低偶氮片段的DBC则表现出向列相的螺纹质构。与具有低偶氮嵌段（≤41wt％）或非偶氮嵌段（≤38wt％）的产生六边形纳米结构的DBC相比，具有49 wt％的偶氮侧链的DBC产生了层状结构。此外，所有DBC在紫外线照射下和不同时间间隔的黑暗存储下均表现出可逆的反式顺式光异构化行为。

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