声-光-力-热耦合作用下光热敏感水凝胶的溶胀变形行为

Swelling and Deformation Behaviors of Photo-Thermal Sensitive Hydrogels under Acousto-Photo-Mechanical-Thermo Coupling Effect

超声波在两种介质间传播时,声动量的转移在界面处产生超声辐射应力引发水凝胶形变。为研究光热敏感水凝胶在超声波、光辐射、机械载荷以及温度耦合作用下的大变形行为,采用变分法建立了光热敏感水凝胶声-光-力-热耦合本构模型,研究了声匹配条件下水凝胶单轴预拉伸时超声波强度、光强和温度对其溶胀行为的影响。研究结果表明:单轴预拉伸数值越大,水凝胶的平衡溶胀率越大;超声波强度越强,水凝胶的平衡溶胀率越大,平衡溶胀率随超声波强度增大呈线性递增关系;而随着温度升高,水凝胶的平衡溶胀率先减小后增大,存在一极小值;平衡溶胀率达到极小值时的温度值随预拉伸和超声波强度的增加而升高,随光强增加而降低;当环境温度超过极小值出现时的温度值后,预拉伸和超声波强度变化对水凝胶溶胀行为几乎没有影响,但光强变化对水凝胶溶胀行为仍有一定影响。

Acoustic wave propagation from external solution into a hydrogel can generate acoustic radiation stress due to acoustic momentum transfer between the two media,which may result in the large deformation of the hydrogel.To analyze the large deformation behavior of photo-thermal sensitive hydrogel under coupling acoustophoto-mechanical-thermo effect,an acousto-photo-mechanical-thermo constitutive model was established through the variational methods.Considering a specified case of photo-thermal sensitive hydrogel with uniaxial constraint,and that the condition of acoustic match was satisfied,the effects of ultrasonic intensity,light intensity and temperature on swelling properties of hydrogel had been analyzed systematically.The results show that the higher the uniaxial pre-stretching value is,the higher the equilibrium swelling ratio of the hydrogel is.The equilibrium swelling ratio of the hydrogel increases linearly with the rise of ultrasonic intensity,but decreases first and then increases with the temperature,and there is a minimum.The temperature at which the equilibrium swelling ratio reaches its minimum increases with the increase of pre-stretching and ultrasonic intensity,but decreases with the increase of light intensity.Once the environment temperature above the critical temperature,the change of pre-stretching and ultrasonic intensity has little effect on the swelling behavior of the hydrogel,but the change of light intensity still has a certain effect on the swelling behavior of the hydrogel.