【作者】 易先君；

【导师】 张淑芬；

【作者基本信息】 大连理工大学 ， 应用化学， 2013， 博士

【摘要】 非高碘酸氧化制备的氧化淀粉中羰基含量通常不高(<0.1)；高碘酸氧化制备高羰基含量氧化淀粉时,氧化淀粉水溶性差,且淀粉分子链易剧烈降解。本文希望设计合成一种水溶性高羰基含量氧化淀粉,并避免淀粉剧烈降解。依据氧化淀粉结构特点,研究了其在金属离子去除和水凝胶制备方面的应用。本文首先设计采用次氯酸钠(NaCIO)/盐酸羟胺(NH2OH·HCl)/溴化钠(NaBr)催化氧化体系,一步制备了氧化淀粉,通过调节NaClO加入速度实现了产品的高羰基含量(DOco=0.40)、高分子量(Mw=5.67×106)和产品中羰基与羧基比例的调控(0.8：1-2.2：1)。研究了产品的溶解性和溶液性质。采用FT-IR和13C-NMR对产品结构进行了表征。利用氧化淀粉与氨基化合物的反应,设计合成了一系列氧化淀粉希夫碱。以氧化淀粉与氨基噻唑的反应为例,详细研究了反应条件对氨基噻唑取代度和氧化淀粉醛基利用率的影响。结果表明,氨基噻唑取代度可分别通过提高反应温度、延长反应时间、增加投料比来实现提高,实现了醛基利用率100%。采用UV、1H-NMR和13C-NMR对产品结构进行了表征。氧化淀粉与水合肼、乙二胺、对苯二胺、盐酸羟胺等氨基化合物反应均可实现氧化淀粉上醛基100%利用。通过调节氨基噻唑取代度制备了结构相似、溶解度不同的氧化淀粉希夫碱,并研究了这些希夫碱的水溶性对Cu2+吸附性能的影响,结果表明,水溶性好的希夫碱吸附效率高,可达到100%。本文合成的氨基噻唑取代度为14.4%的水溶性氧化淀粉希夫碱对Cu2+的吸附量(QCu2+)达到1.18mmol/g,高于相同条件下取代度为78%的双醛淀粉希夫碱对Cu2+的吸附量(0.92mmol/g)。本文设计合成的氧化淀粉-对苯二胺、水合肼、盐酸羟胺希夫碱对Cu2+、Ag+均有很好的吸附性能,特别是基于盐酸羟胺反应制备的希夫碱,不仅制备成本低,而且对Cu2+具有非常好的吸附效果(Q=3.00mmol/g)。本文设计合成了氧化淀粉-壳聚糖水凝胶,依据凝胶分数和溶胀度研究了该水凝胶的制备条件,并对该水凝胶的交联机理进行了研究。首次设计采用冻融法制备了氧化淀粉-羧甲基壳聚糖水凝胶,研究了此水凝胶的交联机理和溶胀性能。结果表明,此水凝胶是基于羰基与氨基反应生成希夫碱的化学交联作用和基于氢键产生的物理交联作用共同形成；此水凝胶在pH=7.4时具有快速响应能力(5min),而在pH=2时响应速度较慢(5h)。设计通过调节水凝胶干燥前的pH值或添加海藻酸钠实现了水凝胶溶胀度对pH的敏感性。更多还原

【Abstract】 Oxidized starch prepared by common oxidants usually had a low carbonyl content (<0.1), except for periodate. Although oxidized starch with high carbonyl content could be prepared by periodate, the obtained product had poor water solubility. In addition, severe degradation of starch chains occured. In this study, a new type of water soluble oxidized starch with high carbonyl content was prepared, and severe degradation of starch chains was prevented. According to the structure characteristic of the oxidized starch, applications of it in the removal of heavy metal ions and preparation of hydrogel were studied.The oxidized starch was prepared using a one-step method with sodium hypochlorite (NaCIO)/hydroxylamine hydrochloride (NH2OH·HCl)/sodium bromide (NaBr) catalytic oxidation system. Furthermore, high carbonyl content (DOCO=0.40), high molecualr weight (Mw=5.67×106) and adjustable molar ratio of carbonyl to carboxyl groups from0.8:1to2.2:1could be achived by controlling the dropping speed of NaCIO. The water solubility and solution properties of the oxidized starch were studied. The structure of the oxidized starch was characterized by FT-IR and13C-NMR spectra.A series of Schiff bases based on the oxidized starch were synthesised by reacting with amino compounds. According to the reaction of oxidized starch and aminothiazole, effect of reaction conditions on the substitution degree of aminothiazole and utilization rate of aldehyde groups of oxidized starch were throughly studied. The obtained results showed that the substitution degree of aminothiazole could be improved by raising reaction temperature, extending reaction time or increasing molar ratio of amino group to carbonyl group. Therefore,100%utilization rate of aldehyde groups was achived. The structures of the Schiff bases were characterized by UV,1H-NMR and13C-NMR spectra. The100%utilization rate of aldehyde groups of the oxidized starch was also achieved in the reaction of oxidized starch with hydrazine hydrate, ethylenedimine, p-Phenylenediamine and hydroxylamine hydrochloride.Oxidized starch based schiff bases with similar structure and different solubilities were synthesised by adjusting the substitution degree of aminothiazole. The synthesised product was then used to study the effect of solubility of Schiff bases on the adsorption of Cu2+. The results showed that the Schiff bases with a better water solubility had a higher adsorption efficiency, up to100%. Oxidized starch based aminothiazole Schiff base with a degree of substitution of14.4%was synthesised. It had a high adsorption capacity (Q) of1.18mmol/g for Cu2+which was higher than that of dialdehyde starch based aminothiazole Schiff base with a degree of substitution of78%(Q=0.92mmol/g). Other Schiff bases such as oxidized starch based p-Phenylenediamine, hydrazine hydrate and hydroxylamine Schiff bases all had a good adsorption capacity for Cu2+and Ag+. Especially, the oxidized starch based hydroxylamine Schiff base not only had a very well adsorption capacity for Cu2+(Q=3.00mmol/g), but also had a low cost.Oxidized starch-crosslinked-chitosan hydrogels were synthesised. Effects of reaction conditions on the preparation of the hydrogels were investigated in detail based on the gelation fraction and swelling ratio. The crosslinking mechanism of the hyrogel was studied. Oxidized starch-crosslinked carboxylmethyl chitosan hydrogels were first synthesised by freezing-thawing process. The crosslinking mechanism and swelling properties of the hydrogel were studied. Results proved that the hydrogels were crosslinked by the combination of hydrogen bonding and Schiff base structure formed by the reaction of carbonyl groups and amino groups. It was also proved that this hydrogels had a fast response ability (5min) at pH7.4and a slower response ability (5h) at pH2. The pH-sensitive hydrogel could be prepared by adjusting the pH value of hydrogel before freeze drying or adding certain amount of sodium alginate.更多还原