Seidler Konstanze, Griesser Markus, Kury Markus, Harikrishna Reghunathan, Dorfinger Peter, Koch Thomas, Svirkova Anastasiya, Marchetti-Deschmann Martina, Stampfl Juergen, Moszner Norbert, Gorsche Christian, Liska Robert
Institute of Applied Synthetic Chemistry, Technische Universität Wien, Getreidemarkt 9/163-MC, 1060, Vienna, Austria.
Christian Doppler Laboratory for Photopolymers in Digital and Restorative Dentistry, Getreidemarkt 9/163-MC, 1060, Vienna, Austria.
Angew Chem Int Ed Engl. 2018 Jul 16;57(29):9165-9169. doi: 10.1002/anie.201803747. Epub 2018 Jun 20.
The formation of networks through light-initiated radical polymerization allows little freedom for tailored network design. The resulting inhomogeneous network architectures and brittle material behavior of such glassy-type networks limit the commercial application of photopolymers in 3D printing, biomedicine, and microelectronics. An ester-activated vinyl sulfonate ester (EVS) is presented for the rapid formation of tailored methacrylate-based networks. The chain transfer step induced by EVS reduces the kinetic chain length of the photopolymer, thus shifting the gel point to higher conversion, which results in reduced shrinkage stress and higher overall conversion. The resulting, more homogeneous network is responsible for the high toughness of the material. The unique property of EVS to promote nearly retardation-free polymerization can be attributed to the fact that after the transfer step no polymerizable double bond is formed, as is usually seen in classical chain transfer agents. Laser flash photolysis, theoretical calculations, and photoreactor studies were used to elucidate the fast chain transfer reaction and exceptional regulating ability of EVS. Final photopolymer networks exhibit improved mechanical performance making EVS an outstanding candidate for the 3D printing of tough photopolymers.
通过光引发自由基聚合形成网络，在定制网络设计方面几乎没有自由度。这种玻璃态网络所产生的不均匀网络结构和脆性材料行为限制了光聚合物在3D打印、生物医学和微电子领域的商业应用。本文提出了一种酯活化乙烯基磺酸酯（EVS），用于快速形成定制的基于甲基丙烯酸酯的网络。EVS引发的链转移步骤缩短了光聚合物的动力学链长，从而将凝胶点转移到更高的转化率，这导致收缩应力降低和总体转化率提高。由此产生的更均匀的网络是材料具有高韧性的原因。EVS促进几乎无阻滞聚合的独特性质可归因于这样一个事实，即在转移步骤之后，不会像在经典链转移剂中通常看到的那样形成可聚合双键。使用激光闪光光解、理论计算和光反应器研究来阐明EVS的快速链转移反应和出色的调节能力。最终的光聚合物网络表现出改进的机械性能，使EVS成为用于打印坚韧光聚合物的3D打印的优秀候选材料。
