Interplay of photopolymerization and phase separation kinetics and the resulting structure-property relationship of photocurable resins
Interplay of photopolymerization and phase separation kinetics and the resulting structure-property relationship of photocurable resins
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DOI：
10.1016/j.polymer.2023.126032
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发表时间：
2023-05
期刊：
影响因子：
4.6
通讯作者：
Lauren Zakrzewski;Yeongsik Kim;Younghan Song;C. Ryu;Chulsung Bae;C. Picu
中科院分区：
文献类型：
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作者：
Lauren Zakrzewski;Yeongsik Kim;Younghan Song;C. Ryu;Chulsung Bae;C. Picu
在这项工作中，我们通过光聚合诱导相分离（photo-PIPS）在亚微米尺度上开发了具有异质微观结构的热固性材料。为此，我们设计了一种基于丙烯酸酯单体季戊四醇四丙烯酸酯（PETA）和甲基丙烯酸酯稀释剂2-乙基己基甲基丙烯酸酯（2-EHMA）的光固化树脂。采用聚丙烯乙二醇（PPG）作为相分离剂。采用自制的光透射仪和动态力学分析（DMA），通过反应光透射率监测相分离。采用实时傅里叶变换红外光谱（FTIR）和扫描电镜（SEM）分别表征了光聚合动力学和微观结构形态。我们观察到双相分离：PETA和2-EHMA由于不同的反应性而分离，而PPG由于不混溶性而随着网络的发展而分离。在两个过程之间观察到协同作用：PPG相分离导致2-EHMA的分离增强。相分离导致散射导致透光率降低，这主要与2-EHMA的分离有关。由于PPG子畴的形成，相分离也会导致刚度的降低。随着PPG分子量的增加和辐照强度的增大，反应动力学得到增强。
In this work we develop thermoset materials with heterogeneous microstructures on sub-micron scales by photopolymerization-induced phase separation (photo-PIPS). To this end, we designed a photo-curable resin based on pentaerythritol tetraacrylate (PETA), an acrylate monomer, combined with 2-ethylhexyl methacrylate (2-EHMA), a methacrylate diluent. Polypropylene glycol (PPG) was used as a phase separation agent. Phase separation was monitored by reactive light transmittance using a custom-built light transmission apparatus and through dynamic mechanical analysis (DMA). The photopolymerization kinetics and the microstructure morphology were characterized using real-time Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM), respectively. We observe double phase separation: PETA and 2-EHMA separate due to different reactivities, while PPG phase separates as the network develops due to immiscibility. A synergy is observed between the two processes: PPG phase separation leads to an enhanced separation of 2-EHMA. Phase separation leads to reduced transmittance due to scattering, which is primarily associated with the separation of 2-EHMA. Phase separation also causes the reduction of stiffness due to the formation of PPG subdomains. The kinetics is enhanced by increasing the PPG molecular weight and increasing the irradiation intensity.