Rapid Processing of Bottlebrush Coatings through UV-Induced Cross-Linking
Rapid Processing of Bottlebrush Coatings through UV-Induced Cross-Linking
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DOI：
10.1021/acsmacrolett.0c00384
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发表时间：
2020-08-18
影响因子：
7.015
通讯作者：
Verduzco, Rafael
中科院分区：
文献类型：
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作者：
Mei, Hao;Mah, Adeline Huizhen;Verduzco, Rafael
瓶刷聚合物可用于引入新的表面特性，包括亲水性、刺激响应性和减少摩擦力。然而，简单、通用和有效的交联瓶刷聚合物薄膜和涂层的方法是有限的。在这里，我们报告了具有不饱和聚降冰片烯主链和硫醇端基侧链的瓶刷聚合物可以根据需要通过紫外线照射进行交联，以产生均匀的不溶性瓶刷聚合物涂层。为了量化紫外光照射(254 Nm)下的交联动力学和效率，我们测量了瓶刷和线型聚合物薄膜在紫外光照射和溶剂清洗后的归一化剩余厚度(NRT)。对于具有硫醇端基聚苯乙烯(PS)侧链的瓶刷聚合物，在1.0J/cm(2)的紫外线剂量下，NRT超过60%，而非官能化的线型PS需要7.9J/cm(2)的剂量才能达到类似的NRT值。紫外光诱导瓶刷PS的快速交联归因于端硫醇侧链与不饱和聚降冰片烯主链的硫醇-烯偶联，FTIR测量和涉及含饱和主链的瓶刷聚合物的对照研究证明了这一点。为了建立这种方法的更广泛的适用性，我们展示了紫外光诱导的端硫基聚甲基丙烯酸甲酯(BB-PMMA-SH)侧链的瓶刷聚合物薄膜和不含硫醇端基的聚乙二醇(BB-PEG)和聚乳酸(BB-PLA)侧链的瓶刷聚合物薄膜。BB-PEG膜和BB-PLA膜的紫外光诱导交联性需要使用多功能硫醇添加剂。最后，我们证明了通过不同的瓶刷聚合物化学成分的顺序沉积和紫外光诱导的交联，可以制备瓶刷聚合物多层膜。这项工作中概述的交联法简单、通用、高效，可生产出保持瓶刷聚合物独特性能和功能的耐溶剂涂料。
Bottlebrush polymers can be used to introduce novel surface properties including hydrophilicity, stimuli-responsiveness, and reduced friction forces. However, simple, general, and efficient approaches to cross-linking bottlebrush polymer films and coatings are limited. Here, we report that bottlebrush polymers with an unsaturated polynorbornene backbone and thiol-terminated side chains can be cross-linked on demand by UV irradiation to produce uniform and insoluble bottlebrush polymer coatings. To quantify the kinetics and efficiency of cross-linking by UV exposure (254 nm), we measured the normalized residual thickness (NRT) of bottlebrush and linear polymer films after UV exposure and solvent washing. For bottlebrush polymers with thiol-terminated polystyrene (PS) side chains, the NRT exceeded 60% for a UV dose of 1.0 J/cm(2), while unfunctionalized linear PS required a dose of 7.9 J/cm(2) to achieve similar NRT values. Rapid UV-induced cross-linking of the bottlebrush PS was attributed to the thiol-ene coupling of the thiol-terminated side chains with the unsaturated polynorbomene backbones, as demonstrated through FTIR measurements and control studies involving bottlebrush polymers with saturated backbones. To establish the broader applicability of this approach, UV-induced cross-linking was demonstrated for thin films of bottlebrush polymers with thiol-terminated poly(methyl acrylate) (BB-PMMA-SH) side chains and those with poly(ethylene glycol) (BB-PEG) and poly(lactic acid) (BB-PLA) side chains which do not contain thiol end groups. UV-induced cross-linking of BB-PEG and BB-PLA films required the use of a multifunctional thiol additive. Finally, we demonstrated that bottlebrush polymer multilayers can be fabricated through sequential deposition and UV-induced cross-linking of different bottlebrush polymer chemistries. The cross-linking process outlined in this work is simple, general, and efficient and produces solvent-resistant coatings that preserve the unique properties and functions of bottlebrush polymers.