Adaptable Networks with Semiorthogonal Two-Stage Polymerizations Enabled by Sequential Photoinitiated Thiol–Ene and Disulfide–Ene Reactions
Adaptable Networks with Semiorthogonal Two-Stage Polymerizations Enabled by Sequential Photoinitiated Thiol–Ene and Disulfide–Ene Reactions
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DOI：
10.1021/acs.macromol.3c01728
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发表时间：
2023-11
期刊：
影响因子：
5.5
通讯作者：
Yunfeng Hu;Shafer Soars;Bruce E. Kirkpatrick;Maciej Podgórski;Nicholas J. Bongiardina;Benjamin D Fairbanks;K. Anseth;Christopher N. Bowman
中科院分区：
文献类型：
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作者：
Yunfeng Hu;Shafer Soars;Bruce E. Kirkpatrick;Maciej Podgórski;Nicholas J. Bongiardina;Benjamin D Fairbanks;K. Anseth;Christopher N. Bowman
连续硫醇烯和二硫烯光聚合和它们在材料应用中的效用，如形状固定，光刻，和全息记录进行了探索。虽然硫醇-烯和二硫键-烯反应都是自由基介导的，并且共享一个共同的反应基团，但它们在反应速率上具有几个数量级的差异，这一事实被用来以顺序和半正交的方式形成具有高特异性的两阶段光聚合物。虽然更快的硫醇-烯反应用于形成第一阶段基质，但随后引发二硫键-烯反应以通过二硫键裂解来破坏交联，并随后形成两倍于新交联的硫醚键。因此，连续的键断裂和形成，使在一个单一的网络的第二阶段的动态行为，被探索和应用在各种情况下。结合两个阶段之间的机械性能的显着差异，动态光聚合物材料能够通过引发第二阶段的聚合，同时被应变和变形的形状固定。然后利用光刻来量化变形样品中的形状保持，揭示了第二阶段固化后约95%的保真度。此外，偏振光显微镜用于更好地了解这些机制如何影响施加应力时材料的机械性能。最后，利用两级系统中的集成网络，利用光致聚合物记录了折射率调制度（Δn）为0.0022、雾度接近于零的全息光栅。
Sequential thiol–ene and disulfide–ene photopolymerizations and their utility in materials applications such as shape fixation, photolithography, and holographic recording were explored. Though thiol–ene and disulfide–ene reactions are both radical-mediated and share a common reactive group, the fact that they have several orders of magnitude difference in the reaction rate was utilized to form two-stage photopolymers with high specificity in a sequential and semiorthogonal manner. While the faster thiol–ene reaction was utilized to form a first-stage matrix, the disulfide–ene reaction was then initiated to break cross-links via disulfide cleavage and subsequently form twice as many thioether bonds as new cross-links. As such, sequential bond breakage and formation, enabling the dynamic behavior in the second stage of a single network, were explored and applied in various scenarios. Combining a remarkable difference in mechanical properties between the two stages, the dynamic photopolymer materials were capable of enabling shape fixation by initiating the second-stage polymerization while being strained and deformed. Photolithography was then utilized to quantify shape retention in deformed samples, revealing a fidelity of approximately 95% following the second-stage cure. Additionally, polarized light microscopy was used to understand better how these mechanisms affect the mechanical properties of the material when stress is applied. Finally, taking advantage of the integrated network in the two-stage system, the photopolymers were employed to record a holographic grating with a refractive index modulation (Δn) of 0.0022 and functionally nearly zero haze.