Ultrafast Photo-Crosslinking of Thiol-Norbornene Opaque Silicone Elastomer Nanocomposites in Air
Ultrafast Photo-Crosslinking of Thiol-Norbornene Opaque Silicone Elastomer Nanocomposites in Air
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DOI：
10.1021/acsapm.1c00440
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发表时间：
2021-10-19
影响因子：
5
通讯作者：
Gautrot, Julien E.
中科院分区：
文献类型：
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作者：
Nguyen, Khai D. Q.;Crespo-Ribadeneyra, Maria;Gautrot, Julien E.
光固化有机硅弹性体在各种先进材料应用中越来越受欢迎，包括软机器人、生物医学设备、微制造、功能涂层和增材制造。然而，氧抑制仍然是传统光自由基固化的主要挑战，限制了应用和加工。在这里，我们报告了一种基于硫醇-双烯的有机硅系统，该系统使用显示末端双烯基团的聚二甲基硅氧烷（PDMS）和高度官能化的硫醇化PDMS，以在环境气氛中实现非常快的固化速度。在不存在惰性气氛保护的情况下，实现了完全固化，在有机硅弹性体表面上没有任何未反应的油性残留物。研究了配方和光引发体系（包括使用可见光引发剂）对有机硅网络的动力学和机械性能的影响。尽管它们不透明，但掺入热解二氧化硅和氧化石墨烯（GO）的纳米复合材料保持快速固化速率（二氧化硅和GO复合材料的胶凝时间分别低于1和5秒），具有无粘性表面。在热转化之后，这提供了具有高于0.1S/m的电导率的复合材料。最后，与传统的室温硫化系统相结合，使有效的双固化复合材料的配方。报道的快速交联硫醇-双烯有机硅对于需要环境固化或加工需要超快反应速率的广泛应用具有吸引力。
Photocured silicone elastomers have become increasingly popular in a variety of advanced materials applications including soft robotics, biomedical devices, microfabrication, functional coatings, and additive manufacturing. Oxygen inhibition, however, remains a major challenge for conventional photoradical curing, limiting applications and restricting processing. Here, we report a thiol-norbornene-based silicone system using a polydimethylsiloxane (PDMS) displaying terminal norbornene groups and a highly functionalized thiolated PDMS to achieve very fast curing speeds in an ambient atmosphere. Complete curing, without any unreacted oily residue on the surface of the silicone elastomer, was achieved in the absence of inert atmosphere protection. The impact of a formulation and photoinitiating system, including the use of visible-light initiators, on the kinetics and mechanical properties of the silicone networks was studied. Despite their opacity, nanocomposites incorporating fumed silica and graphene oxide (GO) retained fast cure rates (gelation times below 1 and 5 s for silica and GO composites, respectively) with tack-free surfaces. After thermal conversion, this afforded composites with conductivities above 0.1 S/m. Finally, combination with a conventional room-temperature vulcanization system enabled the formulation of effective dual-cure composites. The fast crosslinking thiol-norbornene silicones reported are attractive for a wide range of applications where ambient curing is required or where processing requires ultrafast reaction rates.