Zhao Dan, Zhu Guangda, Ding Yong, Zheng Junping
Tianjin Key Laboratory of Composite and Functional Materials, School of Materials Science and Engineering, Tianjin University, Tianjin 300350, China.
Polymers (Basel). 2018 Jun 29;10(7):716. doi: 10.3390/polym10070716.
In this work, a different polymer chain structure was synthesized to study π-π interactions between polymer and reduced graphene oxide (RGO). Polymers with different chain structures were obtained from free radical copolymerization of styrene with 4-cyanostyrene (containing substituted phenyl rings) and 2-vinylnaphthalene (containing naphthalene rings). In this work, the polystyrene, poly(styrene--4-cyanostyrene) and poly(styrene--2-vinylnaphthalene) were named as PS, PSCN and PSNP, respectively. RGO was prepared through modified Hummers' method and further thermal reduction, and nanocomposites were prepared by solution blending. Thus, different π-π interactions were formed between polymers and RGO. Raman and thermal gravimetric analysis (TGA) were used to characterize the interfacial interaction, showing that the trend of the interfacial interaction should be in the order of RGO/PSCN, RGO/PS, and RGO/PSNP. The differential scanning calorimetry (DSC) measurement showed that, compared with polymer matrix, the glass transition temperature (T) of RGO/PS, RGO/PSCN and RGO/PSNP nanocomposites with the addition of 4.0 wt% RGO are increased by 14.3 °C, 25.2 °C and 4.4 °C, respectively. Compared with π-π interaction only formed through aromatic rings, substituent groups changed the densities of electron clouds on the phenyl rings. This change resulted in the formation of donor-acceptor interaction and reinforcement of the π-π interaction at the interface, which leads to increased value of T. This comparative study can be useful for selecting appropriate interaction groups, as well as suitable monomers, to prepare high performance nanocomposites.
在本工作中，合成了一种不同的聚合物链结构，以研究聚合物与还原氧化石墨烯（RGO）之间的π-π相互作用。通过苯乙烯与4-氰基苯乙烯（含取代苯环）和2-乙烯基萘（含萘环）的自由基共聚反应，得到了具有不同链结构的聚合物。在本工作中，聚苯乙烯、聚（苯乙烯-4-氰基苯乙烯）和聚（苯乙烯-2-乙烯基萘）分别命名为PS、PSCN和PSNP。RGO通过改进的Hummers法制备并进一步热还原，通过溶液共混制备纳米复合材料。因此，聚合物与RGO之间形成了不同的π-π相互作用。利用拉曼光谱和热重分析（TGA）对界面相互作用进行了表征，结果表明界面相互作用的趋势应为RGO/PSCN、RGO/PS和RGO/PSNP。差示扫描量热法（DSC）测量表明，与聚合物基体相比，添加4.0 wt%RGO的RGO/PS、RGO/PSCN和RGO/PSNP纳米复合材料的玻璃化转变温度（T）分别提高了14.3℃、25.2℃和4.4℃。与仅通过芳环形成的π-π相互作用相比，取代基改变了苯环上的电子云密度。这种变化导致了供体-受体相互作用的形成和界面处π-π相互作用的增强，从而导致T值升高。该对比研究有助于选择合适的相互作用基团以及合适的单体，以制备高性能纳米复合材料。
