James Jose, Thomas George V, Madathil Akhil Punneri, Nambissan P M G, Kalarikkal Nandakumar, Thomas Sabu
Research and Post-Graduate Department of Chemistry, St. Joseph's College, Moolamattom, Idukki 685591, Kerala, India.
Phys Chem Chem Phys. 2020 Aug 28;22(32):18169-18182. doi: 10.1039/d0cp01417f. Epub 2020 Aug 7.
A series of interpenetrating polymer networks (IPNs) and semi-interpenetrating polymer networks (s-IPNs) of styrene butadiene rubber (SBR) and poly(methyl methacrylate) (PMMA) have been synthesized by adopting the sequential interpenetration and in situ polymerization method. The size and the concentration of free volume defects in these systems are monitored and their variations accurately traced using positron annihilation lifetime (PALS) and coincidence Doppler broadening spectroscopic (CDBS) measurements. The morphologies of the IPNs were analyzed with transmission electron microscopy (TEM), scanning electron microscopy (SEM) and atomic force microscopy (AFM). Confocal Raman mapping had been employed to elucidate the mechanism of PMMA interpenetration in the SBR matrix with reference to the blend ratio. The results of free volume analysis lead to the conclusion that the increase of PMMA content in IPN was accompanied by enhancement of interpenetration in the system. Also the morphology changes from dispersed island pattern to a co-continuous one. Besides, the transport parameters and mechanical behavior of IPNs were studied in detail. The results of PALS and CDBS measurements have found to exhibit striking correlations with the sorption, mechanical properties and morphology of the polymer networks. The specific physics involved in the characterization protocol is effectively utilized to explore the chemistry of IPN formation. This new modality of characterization versus composition uplifts and widens the application prospects of elastomer-thermoplastic IPNs.
采用顺序互穿和原位聚合法合成了一系列苯乙烯-丁二烯橡胶（SBR）与聚甲基丙烯酸甲酯（PMMA）的互穿聚合物网络（IPN）和半互穿聚合物网络（s-IPN）。利用正电子湮没寿命（PALS）和符合多普勒展宽光谱（CDBS）测量来监测这些体系中自由体积缺陷的尺寸和浓度，并准确追踪其变化。通过透射电子显微镜（TEM）、扫描电子显微镜（SEM）和原子力显微镜（AFM）分析了IPN的形态。采用共聚焦拉曼映射，参照共混比例阐明了PMMA在SBR基体中的互穿机理。自由体积分析结果得出结论，IPN中PMMA含量的增加伴随着体系中互穿程度的增强。而且形态从分散岛状图案转变为共连续图案。此外，还详细研究了IPN的传输参数和力学行为。发现PALS和CDBS测量结果与聚合物网络的吸附、力学性能和形态呈现出显著的相关性。表征方案中涉及的特定物理性质被有效地用于探索IPN形成的化学过程。这种表征与组成的新方式提升并拓宽了弹性体-热塑性IPN的应用前景。
