Using lattice-fluid model, a continuous thermodynamic framework is presented for phase-equilibrium calculations for binary solutions with a polydisperse polymer solute. A two-step process is designed to form a real po...Using lattice-fluid model, a continuous thermodynamic framework is presented for phase-equilibrium calculations for binary solutions with a polydisperse polymer solute. A two-step process is designed to form a real polymer solution containing a solvent and a polydisperse polymer solute occupying a volume at fixed temperature and pressure. In the first step, close-packed pure components including solvent and polymers with different molar masses or different chain lengths are mixed to form a closed-packed polymer solution. In the second step, the close-packed mixture, considered to be a pseudo-pure substance is mixed with holes to form a real polymer solution with a volume dependent on temperature and pressure. Revised Freed's model developed previously is adopted for both steps. Besides pure-component parameters, a binary size parameter cr and a binary energy parameter e12 are used. They are all temperature dependent. The discrete-multicomponent approach is adopted to derive expressions for chemical potentials, spinodals and critical points. The continuous distribution function is then used in calculations of moments occurring in those expressions. Computation procedures are established for cloud-point-curve, shadow-curve, spinodal and critical-point calculations using standard distribution or arbitrary distribution on molar mass or on chain length. Illustrative examples are also presented.展开更多
Lower critical solution temperature(LCST)is the critical temperature below which the solution is miscible for all compositions and above which the solution becomes a suspension.The study of LCST properties has become ...Lower critical solution temperature(LCST)is the critical temperature below which the solution is miscible for all compositions and above which the solution becomes a suspension.The study of LCST properties has become a central research topic due to its profound impact on the applications of stimuli-responsive materials.Inspired by the marriage between materials science and supramolecular chemistry,the introduction of supramolecular pairs and interactions into polymeric LCST systems is increasingly practiced.Especially,supramolecular interactions provide precise control over LCST behavior in both water and organic solvents.Furthermore,supramolecular interactions not only control or adjust LCST behavior(supramolecular interaction controlled LCST),but also induce LCST phase behavior in species lack of thermo-sensitive properties(supramolecular interaction induced LCST).In this review,we summarize the applications of supramolecular interactions in LCST systems.By examining the relationship between supramolecular interactions and LCST changes,we further discuss the differences between supramolecular interaction controlled LCST and supramolecular interaction induced LCST.We hope this review will give our readers a snapshot on how the supramolecular interactions influence the LCST behavior in various systems,and benefit them with different applications.展开更多
以羟丙基甲基纤维素与丙烯酰氯为原料,制备了羟丙基甲基纤维素丙烯酸酯;以偶氮二异丁腈为引发剂、以羟丙基甲基纤维素丙烯酸酯为大分子交联剂、N-异丙基丙烯酰胺为单体在N,N-二甲基甲酰胺中70℃下通过自由基聚合反应24 h,制备了温度敏...以羟丙基甲基纤维素与丙烯酰氯为原料,制备了羟丙基甲基纤维素丙烯酸酯;以偶氮二异丁腈为引发剂、以羟丙基甲基纤维素丙烯酸酯为大分子交联剂、N-异丙基丙烯酰胺为单体在N,N-二甲基甲酰胺中70℃下通过自由基聚合反应24 h,制备了温度敏感性水凝胶。用DSC对其相转变温度进行了表征,并测定了不同温度下达到溶胀平衡时水凝胶的溶胀比,进行了水凝胶的去溶胀动力学及干凝胶的再溶胀动力学研究。在聚合过程中,加入羟丙基甲基纤维素丙烯酸酯制得的水凝胶:相转变温度由30℃降为29℃;在10℃时溶胀比由29降为24.8;去溶胀速率加快,例如:该水凝胶在10 m in内失水率由56%降为16%,在30 m in内失水率由86%降为19%;并且减慢了凝胶的再溶胀速率。展开更多
文摘Using lattice-fluid model, a continuous thermodynamic framework is presented for phase-equilibrium calculations for binary solutions with a polydisperse polymer solute. A two-step process is designed to form a real polymer solution containing a solvent and a polydisperse polymer solute occupying a volume at fixed temperature and pressure. In the first step, close-packed pure components including solvent and polymers with different molar masses or different chain lengths are mixed to form a closed-packed polymer solution. In the second step, the close-packed mixture, considered to be a pseudo-pure substance is mixed with holes to form a real polymer solution with a volume dependent on temperature and pressure. Revised Freed's model developed previously is adopted for both steps. Besides pure-component parameters, a binary size parameter cr and a binary energy parameter e12 are used. They are all temperature dependent. The discrete-multicomponent approach is adopted to derive expressions for chemical potentials, spinodals and critical points. The continuous distribution function is then used in calculations of moments occurring in those expressions. Computation procedures are established for cloud-point-curve, shadow-curve, spinodal and critical-point calculations using standard distribution or arbitrary distribution on molar mass or on chain length. Illustrative examples are also presented.
基金National Natural Science Foundation of China,Grant/Award Number:21801203HuxiangYoung Talent Program fromHunan Province,Grant/Award Number:2018RS3036。
文摘Lower critical solution temperature(LCST)is the critical temperature below which the solution is miscible for all compositions and above which the solution becomes a suspension.The study of LCST properties has become a central research topic due to its profound impact on the applications of stimuli-responsive materials.Inspired by the marriage between materials science and supramolecular chemistry,the introduction of supramolecular pairs and interactions into polymeric LCST systems is increasingly practiced.Especially,supramolecular interactions provide precise control over LCST behavior in both water and organic solvents.Furthermore,supramolecular interactions not only control or adjust LCST behavior(supramolecular interaction controlled LCST),but also induce LCST phase behavior in species lack of thermo-sensitive properties(supramolecular interaction induced LCST).In this review,we summarize the applications of supramolecular interactions in LCST systems.By examining the relationship between supramolecular interactions and LCST changes,we further discuss the differences between supramolecular interaction controlled LCST and supramolecular interaction induced LCST.We hope this review will give our readers a snapshot on how the supramolecular interactions influence the LCST behavior in various systems,and benefit them with different applications.
文摘以羟丙基甲基纤维素与丙烯酰氯为原料,制备了羟丙基甲基纤维素丙烯酸酯;以偶氮二异丁腈为引发剂、以羟丙基甲基纤维素丙烯酸酯为大分子交联剂、N-异丙基丙烯酰胺为单体在N,N-二甲基甲酰胺中70℃下通过自由基聚合反应24 h,制备了温度敏感性水凝胶。用DSC对其相转变温度进行了表征,并测定了不同温度下达到溶胀平衡时水凝胶的溶胀比,进行了水凝胶的去溶胀动力学及干凝胶的再溶胀动力学研究。在聚合过程中,加入羟丙基甲基纤维素丙烯酸酯制得的水凝胶:相转变温度由30℃降为29℃;在10℃时溶胀比由29降为24.8;去溶胀速率加快,例如:该水凝胶在10 m in内失水率由56%降为16%,在30 m in内失水率由86%降为19%;并且减慢了凝胶的再溶胀速率。
