非振荡化学反应诱发聚电解质凝胶自激振荡的力学调控研究

Self-oscillation in polyelectrolyte gels, caused by the coupling between nonoscillating chemical reactions and large deformations, is analogous to the pulsation in cardiac muscle cells, locomotion in intestine and periodic release of hormone. Precise control of self-oscillation in polyelectrolyte gels can be critical in fabricating artificial muscles, biomimetic robotics, biological sensors, drug delivery systems and intelligent protection layers. Multiple processes, including reaction kinetics, diffusion and swelling, are concurrent in self-oscillating polyelectrolyte gels. Based on molecular models of polyelectrolyte and reaction kinetics theory, nonlinear field theory is formulated to study diverse behaviors in polyelectrolyte gels. The corresponding numerical simulation methods are also developed to obtain the evolution regularity of concentration of reactants, stress and deformation in the polyelectrolyte gels. The influence of some adjustable system parameters on the mechanical characters of the oscillatory deformation is systematically investigated, where the system parameters include size, arrangement of gel arrays, constrain, prestretch, impact, local constant force. A large number of mechanical methods for regulating the self-oscillation in polyelectrolyte gels are explored to enable new designs of soft active structures based on polyelectrolyte gels.

聚电解质凝胶因非振荡化学反应与溶胀大变形的耦合会产生周期性收缩和膨胀的自激振荡现象，与心肌细胞的收缩膨胀、消化道的蠕动和荷尔蒙的周期释放等生命活动相似。精确调控聚电解质凝胶自激振荡行为对研制人造肌肉、仿生蛇、生物传感器、药物脉冲释放及智能皮肤等仿生智能器件至关重要。聚电解质凝胶自激振荡涉及非振荡化学反应、反应物的扩散、凝胶溶胀大变形等多个过程。本项目拟基于化学反应动力学理论和聚电解质凝胶分子模型，建立考虑化学反应的聚电解质凝胶非线性场理论，研究聚电解质凝胶自激振荡行为。通过发展高效数值方法获得反应物浓度、应力和变形等物理量的演化规律，探讨聚电解质凝胶自激振荡特性与凝胶尺寸、凝胶阵列排布、边界约束、预拉伸、瞬载刺激、局部常载等多个因素的联系规律，探索调控聚电解质凝胶自激振荡的力学途径，为新型智能凝胶器件设计提供新思路。

聚电解质凝胶在非振荡化学反应诱发下能周期性缩胀发生自激振荡，与心肌细胞周期缩胀、消化道蠕动和荷尔蒙周期释放等生命活动相似。精确调控聚电解质凝胶自激振荡行为对研制人造肌肉、仿生蛇、生物传感器、药物脉冲释放及智能皮肤等仿生智能器件至关重要。基于化学反应动力学理论和聚电解质凝胶分子模型，项目组构建可考虑化学反应扩散过程的聚电解质凝胶非线性场理论；具体推演实验较成熟的TS非振荡化学反应凝胶体系的动力学演化方程；利用MATLAB软件建立稳定高效计算模块，分析聚电解质凝胶的自激振荡过程，阐明非振荡化学反应诱发聚电解质凝胶振荡机理，探索调控聚电解质凝胶自激振荡过程的有效途径。研究表明给出化学物浓度与亲水系数间合理关系是建立考虑化学反应聚电解质溶胀动力学模型和揭示非振荡化学反应诱发聚电解质凝胶振荡机理的关键。数值结果表明，凝胶太厚和太薄时都不会发生自激振荡；厚度在一定范围时，化学反应扩散与大变形耦合，反应物因非振荡反应体系双稳特性其浓度会周期变化，诱发凝胶自激振荡。研究成功揭示非振荡化学反应诱发聚电解质凝胶振荡机理并指明调控聚电解质凝胶振荡行为的有效途径。系列算例表明，预拉伸改变凝胶层中溶剂的扩散时间和凝胶层动力学过程，改变预拉伸能有效调控凝胶层溶胀收缩行为，并能发生稳态到振荡态的转变现象。在溶胀收缩过程中，凝胶层对约束基体会施加溶胀力，溶胀力随凝胶层振荡同周期振荡。此膨胀力常被用来触发基体梁变形以制作智能驱动器和传感器。ABAQUS有限元模拟凝胶溶胀的结果表明凝胶细观结构可有效调控整体形貌。受非振荡化学反应诱发聚电解质凝胶振荡机理启发，项目组延伸研究具有类似正反馈的光弹动力学系统，成功解释液晶弹性体梁结构在稳定点光源照射下发生的自激振荡现象。项目丰富了凝胶非线性场理论，揭示了聚电解质凝胶自激振荡机理，获得调控聚电解质凝胶自激振荡的有效途径，为新型智能凝胶器件设计提供新思路。