Dikshit Karan, Bruns Carson J
Materials Science and Engineering Program, University of Colorado Boulder, Boulder, CO, United States.
Paul M. Rady Mechanical Engineering Department, University of Colorado Boulder, Boulder, CO, United States.
Front Chem. 2022 Jul 14;10:923775. doi: 10.3389/fchem.2022.923775. eCollection 2022.
Despite hundreds of studies involving slide-ring gels derived from cyclodextrin (CD)-based polyrotaxanes (PRs), their covalent cross-linking kinetics are not well characterized. We employ chemorheology as a tool to measure the gelation kinetics of a model slide-ring organogel derived from -cyclodextrin/poly (ethylene glycol) PRs cross-linked with hexamethylenediisocyanate (HMDI) in DMSO. The viscoelastic properties of the gels were monitored by small-amplitude oscillatory shear (SAOS) rheology, enabling us to estimate the activation barrier and rate law for cross-linking while mapping experimental parameters to kinetics and mechanical properties. Gelation time, gel point, and final gel elasticity depend on cross-linker concentration, but polyrotaxane concentration only affects gelation time and elasticity (not gel point), while temperature only affects gelation time and gel point (not final elasticity). These measurements facilitate the rational design of slide-ring networks by simple parameter selection (temperature, cross-linker concentration, PR concentration, reaction time).
尽管已有数百项关于基于环糊精（CD）的聚轮烷（PR）衍生的滑环凝胶的研究，但其共价交联动力学尚未得到充分表征。我们采用化学流变学作为工具，来测量在二甲基亚砜（DMSO）中由β-环糊精/聚乙二醇PR与六亚甲基二异氰酸酯（HMDI）交联得到的模型滑环有机凝胶的凝胶化动力学。通过小振幅振荡剪切（SAOS）流变学监测凝胶的粘弹性特性，这使我们能够在将实验参数映射到动力学和力学性能的同时，估算交联的活化能垒和速率定律。凝胶化时间、凝胶点和最终凝胶弹性取决于交联剂浓度，但聚轮烷浓度仅影响凝胶化时间和弹性（不影响凝胶点），而温度仅影响凝胶化时间和凝胶点（不影响最终弹性）。这些测量通过简单的参数选择（温度、交联剂浓度、PR浓度、反应时间）促进了滑环网络的合理设计。
