The present work investigates the structural and dynamical features of Polyvinyl alcohol (PVA) and surfactant–PVA system through the change in the rate of hydrolysis of benzocaine. The UV–Vis spectra of benzocaine showed that the absorbance values at λ_max (284 nm) increased with the increase in PVA. The rate of hydrolysis decreased in the dilute‐ and high‐concentration regions of PVA, whereas it remains unchanged in the mid‐concentration range of PVA, known as the polymer–polymer interaction region. These observations correspond to the structural changes in PVA with the increase in PVA concentration in aqueous solution. The aggregation behavior of PVA was further studied using transmission electron microscopy micrographs. The rate constant for the hydrolysis of benzocaine showed peaked behavior with the increase in [CTABr] in the CTABr‐PVA mixed system. The sodium dodecyl sulphate (SDS) molecules modify the PVA chains into a more compact form, and so, the hydration number around PVA is decreased. Consequently, the less hydrophilic benzocaine entangles with SDS‐PVA, whereas OH^– ions aggregate into the aqueous pseudophase, resulting in a decrease in the rate of hydrolysis in the SDS–PVA mixed medium. The calculated value of binding constant increased with the increase in PVA in both CTABr‐PVA and SDS‐PVA mixed systems.

中文翻译：

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聚乙烯醇在水溶液中的水合行为研究：通过苯佐卡因水解的动力学方法

本工作通过改变苯佐卡因的水解速率来研究聚乙烯醇（PVA）和表面活性剂-PVA系统的结构和动力学特征。紫外-可见苯佐卡因光谱表明在吸光度值λ_最大（284 nm）随着PVA的增加而增加。在PVA的稀浓度和高浓度区域中，水解速率下降，而在PVA的中浓度范围（称为聚合物-聚合物相互作用区域）中，水解速率保持不变。这些观察结果对应于PVA的结构变化，其随着水溶液中PVA浓度的增加而增加。使用透射电子显微镜显微照片进一步研究了PVA的聚集行为。在CTABr-PVA混合体系中，苯并卡因的水解速率常数随[CTABr]的增加而出现峰值。十二烷基硫酸钠（SDS）分子将PVA链修饰为更紧密的形式，因此PVA周围的水合数减少。因此，亲水性较低的苯佐卡因与SDS-PVA缠结，而OH^–离子聚集到假水相中，导致SDS-PVA混合介质中水解速率降低。在CTABr-PVA和SDS-PVA混合系统中，结合常数的计算值都随PVA的增加而增加。