【作者】 刘训恿；

【导师】 程发； 陈宇；

【作者基本信息】 天津大学 ， 高分子化学与物理， 2011， 博士

【摘要】 本论文以超支化聚乙烯亚胺（HPEI）为原料,制备了一系列具有不同低临界溶解温度的新型功能性超支化温敏聚合物,从聚合物本身以及pH值和盐效应几个方面对其水溶液的温敏性质进行了深入研究,发现其性质与传统线形温敏聚合物相比具有较大差异。在此基础上进一步研究了所得超支化温敏聚合物与金纳米粒子复合后的溶液性质及在颜色传感器和催化回收方面的应用,具体内容如下:1.对HPEI端氨基进行异丁酰胺（IBAm）化改性,优选出异丁酸酐为最佳的酰化试剂,通过改变HPEI核的分子量以及异丁酰化程度,成功制备了一系HPEI- IBAm超支化温敏聚合物。2.HPEI-IBAm水溶液的浊点温度（CP）对聚合物的分子量、HPEI氨基的取代度及体系pH值都是敏感的。降低聚合物分子量、减少氨基的取代度、降低体系的pH值都可以有效地使溶液CP值升高。溶液的CP温度在0¹00oC范围内可调。3.相对于传统线形温敏聚合物,HPEI-IBAm水溶液的CP对盐的存在更敏感。高浓度阴离子对HPEI-IBAm的盐析效应顺序为:PO43- >CO3^2- >SO4^2- >S₂O₃^2- >F- >Cl- >Br- ^NO₃^- >I- >SCN^-,符合经典的Hofmeister规律;而低盐浓度下的盐析顺序为:PO43- ^CO3^{2- S}CN^- >I- >NO₃^- >S₂O₃^2- >SO4^2- >Br- >F- >Cl-,与经典的Hofmeister规律相差很大。无机阳离子对HPEI-IBAm溶液CP的影响不如阴离子显著,但也存在明显的不同于线形温敏聚合物的规律,其盐析顺序为:Sr^{2+ B}a²⁺ >Na^{+ K+ R}b+ >Cs⁺ >NH₄^{+ C}a²⁺ >Li^{+ M}g²⁺。有机铵盐对HPEI-IBAm溶液表现出盐溶效应,这种效应随着碳链长度增加而变得非常明显。4.HPEI-IBAm与金纳米粒子复合物的水溶液具有温敏性,其CP温度可以在很宽的范围内调节。该类复合物水溶液在其CP温度附近会发生明显的颜色变化,并且温度响应范围很窄,因此,可以作为敏感的颜色传感器来监测不同环境温度的变化。此外,该复合物溶液的颜色对pH和盐也是敏感的,因此,也可以作为颜色传感器来监测体系pH和盐浓度的变化。5.HPEI-IBAm与金纳米粒子温敏复合物在催化还原4-硝基苯酚反应中具有多重优越性:（1）催化剂可以多次回收再利用;（2）合适的HPEI-IBAm聚合物可以提高金纳米粒子的催化活性;（3）避免催化反应中出现温度过高现象。更多还原

【Abstract】 In this dissertation, a series of new functional hyperbranched thermoresponsive polymers with different lower critical solution temperature were synthesized from hyperbranched polyethyleneimine （HPEI）. The factors influencing the thermoresponsive property of the aqueous solution of these polymers were studied in detail, such as the structures of the polymers, the pH of the solutions and the existence of various salts. It was found that there was obvious difference between the hyperbranched thermoresponsive polymers and the traditional linear thermoresponsive ones in the thermoresponsive property. Based on these results these polymers were used to form themoresponsive composites with gold nanoparticles. The solution properties of these thermoresponsive composites and their applications as colorimetric sensors and recoverable catalysts were further researched. The details were as follows:1. In the process of the modification of the terminal amino groups of HPEI with isobutyric amide （IBAm） groups, the amidation agents were optimized and it was found that isobutyric anhydride was the best one. A series of HPEI-IBAm hyperbranched thermoresponsive polymers were successfully prepared by changing the molecular weight of HPEI core and the degree of substitution （DS） of IBAm groups.2. The cloud point （CP） of the aqueous solution of HPEI-IBAm polymers was sensitive to the alteration of molecular weight and the DS of the polymers and the pH of the aqueous media. Lowering the molecular weight and the DS value of the polymer and increasing the pH of the system can effectively increase the CPof the solution. The CP value can be controlled in a broad temperature range of 0¹00℃.3. The CP of HPEI-IBAm was more sensitive to the salts compared with that of linear thermoresponsive polymer. At high salt concentration, the specific ranking of inorganic anions in salting-out HPEI-IBAm polymer was as follows: PO43- >CO3^2- >SO4^2- >S₂O₃^2- >F- >Cl- >Br- ^NO₃^->I- >SCN^-. This sequence is in accordance with the well-known Hofmeister series. However, at low salt concentration, the specific ranking of inorganic anions in salting-out HPEI-IBAm polymer was as follows: PO43- ^CO3^{2- S}CN^- >I- >NO₃^- >S₂O₃^2- >SO4^2- >Br- >F- >Cl-. Anti-Hofmeister phenomenon can be found in both monovalent and divalent inorganic anions. The cations’effect on the CP of HPEI-IBAm aqueous solutions was not so significantly as anions, however, the cations ranking ordering for HPEI-IBAm also showed obvious difference from that of the linear thermoresponsive polymers. The specific ranking order of inorganic cations in salting-out HPEI-IBAm polymer was as follows: Sr^{2+ B}a²⁺ >Na^{+ K+ R}b+ >Cs⁺ >NH₄^{+ C}a²⁺ >Li^{+ M}g²⁺. The organic ammonium salt showed obvious salting-in effect in the certain salt concentration region. The salting-in effect of ammonium chloride salts can be enhanced significantly by increasing the length of their aliphatic chains.4. The composites of gold nanoparticles with HPEI-IBAms were thermoresponsive, and their CPs could be adjusted in a broad temperature range. Upon raising the temperature near the CP, the color of the obtained thermoresponsive composites changed sharply in a narrow temperature range. Thus, the obtained thermoresponsive composites were suitable to be used as colorimetric sensors for detecting the environmental temperature variation. Furthermore, the solution colors of the thermoresponsive composites were also sensitive to the pH and salts of the system, resulting that they could also be used as colorimetric sensors for detecting the variation of pH and salt concentration.5. The obtained thermoresponsive gold nanoparticles could be used as responsive catalysts for the catalytic reduction reaction of 4-nitrophenol. The advantages are as follows: （1） catalysts could be recycled several times. （2） Appropriate HPEI-IBAm polymer could improve the catalytic activity of the gold nanoparticles. （3） The sudden significant increase of the reaction temperature above the pre-set one could be avoided.更多还原