Department of Craniofacial Biology, School of Dental Medicine, University of Colorado Anschutz Medical Campus, Aurora, USA.
Department of Craniofacial Biology, School of Dental Medicine, University of Colorado Anschutz Medical Campus, Aurora, USA.
J Mech Behav Biomed Mater. 2018 Sep;85:218-224. doi: 10.1016/j.jmbbm.2018.06.003. Epub 2018 Jun 2.
The enhanced in situ photopolymerization kinetics of methyl methacrylate (MMA) to poly(methyl methacrylate) (PMMA) through the incorporation of both inert and reactive nanogel (NG) fillers under ambient conditions has been demonstrated. In addition to the polymerization kinetics, the physical and chemical properties of the prepolymeric NG were also utilized to tune the thermoplasticity and mechanical properties of the PMMA polymer network. The protocol followed in this study imparts superior MMA photopolymerization kinetics (≥ 60% double-bond conversion within 15 min for > 35 wt% nanogel loadings and ≥ 95% double-bond conversion in < 60 min for all NG concentrations) when compared with traditional polymerization mechanisms. PMMA remained a glassy material following the incorporation of both inert and reactive NG as demonstrated by the glass transition temperature (T) of the ultimate networks. Network linearity is uncompromised following incorporation of inert NG additives, thereby preserving the thermoplasticity of the PMMA network. As the non-functionalized, inert NG content increases, the maintenance of thermoplasticity occurs at the expense of mechanical properties (10× reduction of maximum strength at 25 wt% loading). These effects are less pronounced when reactive nanogels are employed (no significant reduction of maximum strength at 25 wt% loading with minimal crosslinking). The incorporation of NGs enable high chemical tunability within linear polymer networks. Given the wide range of monomers available for the synthesis of NGs, the methodology detailed in this study offers a scheme for the optimization of linear networks for specific targeted applications, hitherto deemed unrealistic under established polymerization protocols.
本研究采用惰性和反应性纳米凝胶（NG）作为填充剂，在环境条件下提高了甲基丙烯酸甲酯（MMA）的原位光聚合动力学，使其转化为聚甲基丙烯酸甲酯（PMMA）。除聚合动力学外，预聚物 NG 的物理和化学性质也被用于调节 PMMA 聚合物网络的热塑性和机械性能。与传统聚合机制相比，本研究采用的方案赋予了 MMA 光聚合动力学的优越性（在 35wt%以上纳米凝胶负载下，15 分钟内双键转化率达到≥60%，所有 NG 浓度下，60 分钟内双键转化率达到≥95%）。惰性和反应性 NG 的加入使 PMMA 仍保持为玻璃态材料，这可通过最终网络的玻璃化转变温度（T）证明。惰性 NG 添加剂的加入不会影响网络的线性，从而保持 PMMA 网络的热塑性。随着非官能化惰性 NG 含量的增加，热塑性的保持是以机械性能为代价的（在 25wt%负载下最大强度降低 10 倍）。当使用反应性纳米凝胶时，这些影响不太明显（在 25wt%负载下，交联最小，最大强度没有明显降低）。NG 的加入使线性聚合物网络具有高的化学可调性。考虑到可用于合成 NG 的单体种类繁多，本研究详细介绍的方法为针对特定目标应用优化线性网络提供了一种方案，而在现有的聚合方案中，这些应用被认为是不现实的。
