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通过分子结构设计,合成了疏水性单体4-乙酰基丙烯酰乙酸乙酯(AAEA),并以该单体与丙烯酸(AA)进行自由基溶液共聚,制备了P(AAEA-co-AA)新型温度敏感性水凝胶.AAEA的1HNMR及FT-IR分析表明,该单体主要以烯醇式结构存在;P(AAEA-co-AA)的FT-IR分析发现,PAAEA与PAA之间存在较强烈的氢键作用,使得AAEA烯醇异构体中的C—O伸缩振动吸收峰移向了低波数处.对冷冻干燥后凝胶的电镜分析发现,当AAEA用量较高时,由于凝胶内部分子链段的疏水聚集,各部分溶胀度以及溶胀速度不均一而使得凝胶表面粗糙不平.采用DSC对凝胶的体积相转变进行了研究,结果表明,该水凝胶的体积相转变温度(VPTT)在48.2至61.8℃之间,并且随着AAEA用量的减小,凝胶的VPTT逐渐增加.对该新型温度敏感性水凝胶在去离子水中的溶胀动力学研究发现,当AAEA用量高于4.6g时,凝胶属于Fick凝胶;反之凝胶则属于非Fick凝胶.该水凝胶在去离子水中具有良好的温度敏感性,当外界温度低于VPTT时,凝胶能保持溶胀状态;而当外界温度高于VPTT时,凝胶的平衡溶胀度迅速下降,表现为温度敏感性.进一步研究发现,凝胶组成不仅会影响凝胶的VPTT,而且会影响凝胶温度敏感性的强弱.
Through the molecular structure design, the hydrophobic monomer ethyl 4-acetoacetoxyacetate (AAEA) was synthesized and the solution of P (AAEA-co-AA) was prepared by radical copolymerization of this monomer with acrylic acid (AA) The results of 1HNMR and FT-IR analysis of AAEA showed that the monomer mainly existed in the enol structure. The FT-IR analysis of P (AAEA-co-AA) showed that there was between PAAEA and PAA The stronger hydrogen bond makes the C-O stretching vibrational absorption peak of AAEA enol isomer shift to the low wave number.After electron microscopy analysis of freeze-dried gel, when AAEA dosage is higher, The results showed that the volume phase transition of the hydrogel was studied by means of DSC. The phase transition of the gel was studied by means of DSC, (VPTT) was between 48.2 and 61.8 ℃, and the VPTT of the gel gradually increased with the decrease of AAEA dosage.Studying the swelling kinetics of the new temperature-sensitive hydrogel in deionized water, it was found that when the AAEA When the amount is higher than 4.6g, the gel belongs to the Fick gel, whereas the gel belongs to the non-Fick gel. The hydrogel The deionized water has a good temperature sensitivity, when the outside temperature is lower than VPTT, the gel can maintain the swelling state; when the outside temperature is higher than the VPTT, the equilibrium swelling degree of the gel decreases rapidly, showing the temperature sensitivity. The study found that the gel composition not only affects the VPTT of the gel, but also affects the gel temperature sensitivity.