National Institute of Standards and Technology, Gaithersburg, MD 20899, USA.
Soft Matter. 2017 May 31;13(21):3975-3983. doi: 10.1039/c7sm00419b.
We present a method that combines experimental and computational approaches to assess a comprehensive set of structural and functional evolution during a network formation process via photopolymerization. Our work uses the simultaneous measurement of the degree of conversion, polymerization stress, the change in reaction temperature, and shrinkage strain in situ. These measurements are combined with the theory of viscoelastic materials to deduce the relaxation time and frequency-dependent modulus of the polymerizing network. The relaxation time and degree of conversion are used to demonstrate the effect of processing parameters (e.g. curing protocol adjusted by the light intensity) in creating different network structures for the same initial resin. We describe experimental trends using effective medium calculations on a cross-linked polymer network model. In particular, we show that the effect of curing conditions on the spatial heterogeneity in crosslink density can be quantified using multiparametric measurements and modeling. Collectively, the present method is a way to examine holistically the complex structural and functional evolution of the network formation process.
我们提出了一种方法，该方法结合了实验和计算方法，通过光聚合来评估网络形成过程中结构和功能的综合演变。我们的工作使用了同时原位测量转化率、聚合应力、反应温度变化和收缩应变的方法。这些测量结果与粘弹性材料理论相结合，推导出聚合网络的松弛时间和频率相关的模量。利用松弛时间和转化率，展示了加工参数（例如通过光强度调整的固化方案）对相同初始树脂产生不同网络结构的影响。我们使用交联聚合物网络模型的有效介质计算来描述实验趋势。特别是，我们表明，使用多参数测量和建模可以量化固化条件对交联密度空间异质性的影响。总的来说，本方法是一种全面研究网络形成过程中复杂结构和功能演变的方法。
