Miglani Chirag, Joseph Jojo P, Gupta Deepika, Singh Ashmeet, Pal Asish
Chemical Biology Unit, Institute of Nano Science and Technology Sector 81 Mohali Punjab-140306 India
RSC Adv. 2021 Dec 10;11(62):39376-39386. doi: 10.1039/d1ra07425c. eCollection 2021 Dec 6.
Efficacy and durability of the photovoltaic device mandates its protection against hot, humid weather condition, high energy of UV light and unwanted scratches. Such challenges can be mitigated by smart polymeric coating with inherent properties hydrophobicity to prevent moisture, optimal viscocity for better processibility and crack-healing. The hydrophobic polymers TP1-TP4 containing pendant photo-crosslinkable thymine moieties are designed that undergo [2 + 2] photocycloaddition upon UV irradiation and can be dynamically reverted back upon irradiation with UV light. A judicious control of solvent environment, chain length, functionality% and concentration of the polymers regulate the aspects of photodimerization thereby, rendering intra or inter-chain collapse to form diverse nanostructures. Photodimerization of the thymine moieties renders coil to globule transformation in dilute condition whereas irradiation performed at high macromolecular concentration regime exhibits higher order nanostructures. The photoresponsive chain collapse leads to the formation of rigid crosslinked domains within flexible polymer chains akin to the hard-soft phases of thermoplastic elastomers. Such rigidification of the crosslinked segments endows a tool to photomodulate the glass transition temperature ( ) that can dynamically revert back upon decrosslinking. Further, the structural modulation of the polymers is explored towards autonomic and nonautonomic self-healing behaviour at ambient conditions. Moreover, the self-healing efficacy can be tuned with the film thickness and it remains unaltered upon using solar simulator or direct sunlight. Overall, such hydrophobic low polymers display photo-regulated self-healing mechanism consisting of both autonomic and non-autonomic self-healing and may find applications in designing smart protective coatings for photovoltaic devices.
光伏器件的功效和耐久性要求对其进行保护，以抵御炎热、潮湿的天气条件、高能紫外线以及不必要的划痕。通过具有固有特性的智能聚合物涂层可以缓解这些挑战，这些特性包括防止水分的疏水性、利于更好加工性的最佳粘度以及裂纹修复能力。设计了含有侧基可光交联胸腺嘧啶部分的疏水聚合物TP1-TP4，它们在紫外线照射下会发生[2 + 2]光环加成反应，并且在紫外线照射后可以动态恢复原状。对聚合物的溶剂环境、链长、官能度和浓度进行明智的控制，可以调节光二聚化的各个方面，从而使链内或链间塌陷形成各种纳米结构。胸腺嘧啶部分的光二聚化在稀溶液条件下会导致从线圈到球体的转变，而在高分子浓度条件下进行照射则会呈现更高阶的纳米结构。光响应性链塌陷导致在柔性聚合物链内形成类似于热塑性弹性体硬软相的刚性交联域。这种交联段的刚性化赋予了一种调节玻璃化转变温度（ ）的工具，该温度在去交联后可以动态恢复。此外，还探索了聚合物的结构调制，以实现环境条件下的自主和非自主自修复行为。此外，自修复功效可以通过膜厚度进行调节，并且在使用太阳模拟器或直射阳光时保持不变。总体而言，这种疏水性低 聚合物表现出由自主和非自主自修复组成的光调节自修复机制，可能在设计光伏器件的智能保护涂层中找到应用。
