【作者】 袁洪亮；

【导师】 具本植；

【作者基本信息】 大连理工大学 ， 应用化学， 2012， 硕士

【摘要】 本文设计以烯丙基缩水甘油醚(AGE)为疏水化试剂,通过调节淀粉衍生物的亲水亲油平衡制备温敏性淀粉。在制备2-羟基-3-烯丙氧基丙基淀粉醚中,探索了该反应体系中溶剂水的用量、碱的用量、反应温度以及反应时间对反应的影响,其最佳条件为：碱用量n(NaOH):n(AGU)为0.7,水用量m(H20)：m(AGU)为2.5：1,反应温度70℃和反应时间为5h。利用IR>1H-NMR等分析手段对产物的结构进行表征以及取代度(DS)的计算。对不同取代度的2-羟基-3-烯丙氧基丙基淀粉醚(HAPS)进行了温敏性能测试,发现当取代度达到0.91以上,制备的产物具有很好的温敏性能。考察了取代度、AGE浓度以及盐浓度对HAPS温敏性的影响,发现随着取代度,产物浓度以及盐浓度提高,可以降低HAPS的临界溶解温度(LCST)。认为LCST能够通过改变DS进行有效地调整。通过荧光分析法测定HAPS能形成稳定胶束,发现随着取代度的提高临界胶束浓度随之降低。淀粉链上接枝2-羟基-3-烯丙氧基丙基不仅赋予淀粉衍生物温敏性能,由于烯丙基的引入,为淀粉衍生物的进一步功能化奠定了基础。本文进一步设计利用巯基乙胺盐酸盐与HAPS进行thiol-ene点化学反应,通过引入弱碱性氨基制备具有pH敏感性的2-羟基-3-(3’-氨乙硫基丙氧基)丙基淀粉醚(以下简称HAEPS)。通过酸碱滴定测定其pKa值以及计算不同pH条件下的离子化度。发现HAEPS的pKa值随着氨基取代度的提高而增大。通过动态光散射(DLS)考察了在不同pH条件下HAEPS的粒径变化以及Zeta电位变化,发现随着pH的增加由于去离子化后HAEPS侧链疏水性增强,导致粒径不断下降。当pH<pKa时HAEPS的Zeta电位保持稳定,而pH>pKa时Zeta电位迅速下降,说明pKa是HAEPS在水溶液中分散稳定性的一个标尺。最后通过表面张力以及荧光测试的进一步证实,在碱性条件下HAEPS能够聚集形成胶束结构。更多还原

【Abstract】 In this study, temperature-responsive2-hydroxy-3-allyloxypropyl starch (HAPS) was prepared using allyl glycidyl ether (AGE) as hydrophobic reagent. And the effects of solution dosage, base dose, reaction time and temperature were studied. Optimal conditions were explorered as following:n(AGE):n(AGU)=l:l, amount of solvent m(H20):m(AGU)=4:1, n(NaOH):n(AGU)=1.5:1, reaction time5h, reaction temperature70oC.IR and’H-NMR were used for characterization of HAPS and degree of substitution (DS) of AGE was also calculated. The property of HAPS with varying DS was analyzed and when DS is0.91or larger, the modified starch has temperature responsity in aqueous solution. Lower critical solution temperature (LCST) was measured by transmittance which is lower increasing DS. And the concentration of HAPS and salt make LCST lower. Results showed that LCST could be adjusted easily by changing DS. The critical micelle concentrations (CMC) of HAPS forming micelles was determined by the fluorescent spectra of pyrene, and found to be decreased against increase of DS.The introduction of allyl made the starch dervatives sensitive to temperature and was important for further functionlization.2-hydroxy-3-(3’-aminoethylthiopropoxy) propyl starch (HAEPS) was prepared through thiol-ene click reaction between HAPS and cysteamine hydrochloride.The pKa and degree of ionization of HAEPS were determined by base-acid titration and it was found that pKa value increased with the increase of the amino group.The size and zeta potential of HAEPS under different pH were measured. With pH increasing, the size decreased gradually which was caused by deionization of HAEPS and the long side chain turning hydrophobic and aggregation. If pH<pKa, zeta potential of HAEPS aqueous sulotion kept stable and it decreased rapidly as pH>pKa, so pKa was used to determine the stability of HAEPS. Surface tentions and fluorescent spectra were also investigated at different pH for further proving the micellization behavior of HAEPS under alkaline solution (pH>9) by adjusting pH of the solution.更多还原