【作者】 苗宗成；

【导师】 李仲谨；

【作者基本信息】 陕西科技大学 ， 应用化学， 2010， 博士

【摘要】 多元吡喃葡萄糖环基微球是淀粉的一种衍生物,是通过交联剂对淀粉分子的交联作用,形成孔道发育良好,具有微空腔结构的微米级微球。多元吡喃葡萄糖环基微球由于孔道的吸附及微空腔的包络吸附作用,赋予了其独特的性质和用途,尤其作为吸附材料,在环境保护、药物负载、交换与吸附等领域具有更加广阔的应用前景。多元吡喃葡萄糖环基微球由于存在着特殊的微空腔的“闭区间”结构,微空腔内受到电子云的屏蔽作用形成了一定的高电子云密度中心,可以与分子大小配伍的客体分子发生包络作用,这种包络作用赋予了多元吡喃葡萄糖环基微球不同于传统微球的吸附性能。在多元吡喃葡萄糖环基微球的吸附过程中既存在“开区间”孔道的范德华力、氢键作用力等的吸附,也存在“闭区间”微空腔主客体分子间的匹配作用的吸附,我们把这种吸附称为双相选择性吸附。本论文研究以可溶性直链淀粉为起始原料,N,N’-亚甲基双丙烯酰胺为交联剂,采用反相悬浮聚合法制备了多元吡喃葡萄糖环基微球,具体操作为：称取适量可溶性淀粉加入蒸馏水中,加热溶解配制成质量浓度为15%的淀粉溶液,量取30mL该淀粉溶液并加入0.2gN,N’-亚甲基双丙烯酰胺,充分溶解后,逐滴加入油相(90mL环己烷和1g分散剂,充分混匀后使用,其中分散剂为m Tween20: m Span80= 3:1)中,保持65℃搅拌反应,形成均匀的液滴后加入0.04gK2S2O8-NaHSO3引发聚合反应,并保持反应2h。反应完成后离心,除去上层油相,下层交联聚合物依次用60-70℃蒸馏水、无水乙醇、丙酮超声洗涤,真空室温干燥20h,得到充分分散白色粉末状多元吡喃葡萄糖环基微球。淀粉分子和交联剂N,N’-亚甲基双丙烯酰胺在引发剂的作用下发生交联共聚反应。随交联度上升,淀粉分子链节间作用力增强,结构更紧密,最终形成空间网状结构微球体并从水相中析出。淀粉分子因被交联而逐渐收缩并将其中的水分挤出,在微球内留下许多微通道,构成了微球孔道。淀粉分子在与N,N’-亚甲基双丙烯酰胺交联的过程中由吡喃葡萄糖上的醇羟基与不同分子链,或与同一分子链上的醇羟基通过交联剂发生交联作用聚合成球,在这个过程中淀粉本身分子构序被重新分配,形成新的聚合体。由于在交联过程中主要是吡喃葡萄糖上2位上的羟基与交联剂发生作用,淀粉分子是由多个吡喃葡萄糖组成,这就直接导致交联过程在这样的规律下具有一定的无规性。在这种有规伴着无规的作用下,交联过程会发生两种情况,一种是多条淀粉分子链通过交联作用后没有形成“闭区间”,也就是多个吡喃葡萄糖没有首尾相连形成环状；另一种是同一条淀粉链或者多条淀粉链经交联后形成了“闭区间”,也就是说多个吡喃葡萄糖形成了首尾相连的环状结构,但是这种环状的结构受交联无规性的影响,就会产生大小不同的环,这些环是由个数不同的吡喃葡萄糖所组成,这些环的大小同样具有无规性,这些个数不同的吡喃葡萄糖所组成的环就构成了微球内部的微空腔结构。通过单因素探讨获得了制备微球的最佳工艺条件,并通过扫描电镜、偏光显微镜、傅立叶红外光谱、x-射线衍射、综合热力学分析仪等仪器对微球的结构和性能进行了表征,进一步测定了微球的零电荷点、比表面积、孔容积、表面化学特性、粒径分布、溶胀度、溶解性、吸水性,并对微球的细胞毒性进行了探讨。多元吡喃葡萄糖环基微球呈圆球形结构,分散性好,无粘连,粒度均匀,表面化学官能团组成明显异于可溶性淀粉。微球在水介质中溶胀且易被亚甲基蓝着色,预示其具有优异的吸附性能。微球的零电荷点为pH3.75,孔容dVp/dDp为0.219,平均孔径DBJH为14.28nm,微球的总酸度为11.81mmol·g-1,微球表面总碱度为2.83mmol·g-1,微球表面羟基含量为10.19mmol.g-1,粒径主要分布在120μm-150μm之间,经细胞毒性试验发现微球没有生物毒性。淀粉分子链与N,N’-亚甲基双丙烯酰胺的交联作用破坏了分子链的规整性,使分子间作用力、氢键明显变弱,导致淀粉结晶能力降低和热稳定性的增加。论文首先探讨了多元吡喃葡萄糖环基微球对金属离子Cu2+ Co2+、Ni2+的吸附性能,当pH值较低时,特别是当pH值低于微球表面零电荷点时,微球表面的羟基和乙酰氨基受质子化的作用强,使得氧原子和氮原子上的孤对电子被质子的空轨道占领,从而降低或失去了与金属离子空轨道配位能力；而pH值较高时,金属离子因为强烈水解而改变存在形态,也不易于被多元吡喃葡萄糖环基微球吸附。随金属离子溶液浓度的增大,对三种金属离子的吸附量快速增加,但当浓度增大到一定程度后,吸附量增加,吸附速度开始减慢,最后出现转折点,吸附量不再增加。温度升高,金属离子在水溶液中的运动能力增强,微球表面配位基团的的极化度也会增加,这两方面的增加导致微球与金属离子的配位吸附作用相对减弱,进而导致微球对金属离子吸附能力减弱；另一个原因可能是温度升高,金属离子水解作用趋势相对更加明显,进而导致其被微球的吸附力相对减弱,随着温度的升高,多元吡喃葡萄糖环基微球对金属离子的吸附递减。微球对金属离子的吸附动力学表现在吸附开始时,金属离子主要被吸附在微球的外表面,吸附较快；随着吸附过程进行,金属离子的浓度逐渐减小,同时金属离子沿微球微孔向内部扩散,扩散阻力渐增,吸附速率主要受扩散速度的控制,导致吸附速率变慢；吸附后期,主要在微球内表面吸附,且浓度差推动力越来越小,吸附已基本达到平衡。微球对金属离子的吸附热力学表现为其吸附行为既符合Langmuir等温吸附方程和Freundlich等温吸附方程,且在不同温度下,拟合得到的n都大于1,则表明微球对金属离子的吸附是“优惠吸附”过程。吸附过程是放热的,降低温度有利于吸附,且多元吡喃葡萄糖环基微球对金属离子以物理吸附为主,焓变ΔH是主要的吸附驱动力。微球吸附金属离子后,由于配位作用的影响,使得微球结构中发生配位作用的部分受到金属离子吸电子作用的影响,导致电子云密度增加,所以微球吸附金属离子后红外吸收振动峰、晶体结构及热稳定性都会发生变化,且变化程度与金属离子的吸附量成正比的线性关系。在研究了多元吡喃葡萄糖环基微球对金属离子的吸附性质后,论文中进一步研究了微球对有机化合物苯酚、四氢呋喃和吡啶的吸附性能。多元吡喃葡萄糖环基微球对有机化合物的吸附动力学特性表现在开始时吸附速率较快,随着吸附时间的延长吸附速率逐渐逐渐减小。一级吸附动力学方程和二级动力学方程都能够对有机物在多元吡喃葡萄糖环基微球上的吸附动力学性能进行拟合,都得到比较满意的效果,说明吸附同时受液膜扩散和颗粒内扩散过程控制,这也说明多元吡喃葡萄糖环基微球对有机物的吸附行为既存在物理因素也存在化学的因素。微球对有机物苯酚、四氢呋喃、吡啶吸附行为与Langmuir方程和Freundlich方程的拟合程度都较好,即说明多元吡喃葡萄糖环基微球对实验的三种有机物的吸附行为既符合Langmuir等温吸附方程和Freundlich等温吸附方程,但是相比较之下,对于苯酚和四氢呋喃与Freundlich方程具有更好的拟合程度,而对于吡啶来说与Langmuir方程具有更好的拟合程度。且在不同温度下,拟合得到的1/n都小于1,说明微球对苯酚、四氢呋喃、吡啶吸附是“优惠吸附”过程。吸附过程是放热的,降低温度有利于吸附,且多元吡喃葡萄糖环基微球对有机化合物以包络吸附为主,焓变ΔH是主要的吸附驱动力。微球吸附有机化合物后,在孔道产生吸附的有机化合物会和孔道中的羟基、氨基等产生氢键作用,使得微球结构中发生作用的部分受到有机化合物的影响会发生变化。而在微球微空腔中包络吸附的有机化合物由于与微球是靠范德华力结合,所以对微球的结构影响不大。在本论文的研究中,红外光谱、综合热分析和x-射线衍射等仪器用于分析有机化合物对微球结构性能的影响。结合吸附行为及热力学函数分析结果表明,微球的吸附作用主要以物理吸附为主导,说明微球吸附容量的贡献主要来自于较大的比表面积和孔容积及发达的多元吡喃葡萄糖环结构,微球吸附金属离子主要依靠孔道来进行,而对于可包络于微空腔内部的有机化合物而言则主要是依靠于微空腔来进行,多元吡喃葡萄糖环基微球对吸附质的吸附作用是孔道和微空腔双相选择吸附作用的结果。更多还原

【Abstract】 Mult-glucopyranose microsphere is a kind of derivation of starch. It has favorable channel, microcavity and micrometer size through crosslinking action to starch molecular. For coexisting of adsorption of channel and microcavity, mult-glucopyranose microsphere has special properties and performance, especially in the fields of adsorption, environmental protection, loading-drug, material exchange, and so on, it will show broad application prospect. The structure of the microcavity in the mult-glucopyranose microsphere could adsorb guest molecule with suitable size for the shielding of electron cloud to form certain higher electron cloud density center. Because of the inclusion adsorption, in the mult-glucopyranose microsphere has more excellent adsorption than general microsphere. The adsorption process of the microsphere toward guest was composed with the adsorption of "open interval" including of van der waals force, hydrogen-bonding force, dispersion force, and so on, and the adsorption of "close interval" of the action of host-guest matching in the microcavity. The excellent adsorption is called biphasic-selective adsorption.The mult-glucopyranose microsphere was prepared from starch as crude materials and N, N’-methylenebiacrylamide as crosslinking reagent in inverse suspension.30mL 15% (wt) starch solution and 0.2g N, N’-methylenebiacrylamide were added in the reaction vessel until dissolution completely, and then were dropped in the oil phase which was composed by 90mL cyclohexane,0.75g Tween 20 and 0.25g span80. After oil phase formed uniform droplet,0.04g K2S2O8-NaHSO3 was added to initiate the polymerization at 65℃with stiring and the reaction was remained two hours. After reaction, the centrifugation operation was used to separate the oil, and the polymer in the bottom was treated with distilled water, anhydrous alcohol, acetone in turn by ultrasonic washing. And then the polymer was dried at room temperature in vaccum for 20 hours, so we will obtain the mult-glucopyranose of white powder fully dispersed.The cross-linked copolymerization was prepared with starch and N, N’-methylenebiacrylamide as the rude materials. The force between different starch molecular chains enhances the structure more closely with the cross-linking degree of increase and eventually to form a spatial network structure microsphere precipitation from aqueous solution. Starch molecules gradually shrink due to cross-linked and the water is moistured out of them, a number of micro-channel left in the microspheres which constitutes a microsphere pore. The starch molecular structure has been redistributed in the cross-linking to form a new polymer.Starch molecules are formed by a number of glucopyranose, the second hydroxyl of lglucopyranose and the cross-linking play a role in the process of the cross-linking, which led directly to cross-linking process has a certain random nature under the laws. Two cases occurred in the cross-linking process accompanied by such a regulation under the effect of random, the one is a number of starch molecular chains did not form a "closed zone" after the adoption of cross-linking, that is, there is no a ring connected end to end formed by a number of glucopyranose; the other is the "closed zone" formed by the same starch chain, or a number of cross-linking of starch chains, that is,the ring connected end to end is formed by a number of glucopyranose, and the different sizes of the ring can be produced for the random nature of cross-linking, which is formed by a number of different glucopyranose, the random nature is as well as the size of the ring.and the micro-cavity structure inside of micro-ball is constituted by the ring composed of number of different glucopyranose.Obtained the optimum conditions of microsphere through the preparation of single-factor micro-structure and properties of the ball were characterized by scanning electron microscopy, polarizing microscopy, Fourier transform infrared spectroscopy, x-ray diffraction, a comprehensive thermodynamic analysis instrument and other equipment,which further measured microspheres point of zero charge, surface area, pore volume, surface chemical properties, particle size distribution, degree of swelling, solubility, water absorption and cell toxicity were discussed. Mult-glucopyranose microsphere cylindrical spherical structure, which composition of surface chemical functional groups are significantly different from that of soluble starch,and has many advatages such as good dispersion, no adhesion, uniform particle size and so on.Indicator of methylene blue is easily colored to signal the excellent adsorption properties of microspheres in water medium.The zero charge point of microspheres is pH 3.75, pore volume dVp/dDp is 0.219, the average pore size DBJH is 14.28nm, the total acidity of micro-ball is 11.81 mmol·g-1, a total alkalinity of microspheres on the surface is 2.83 mmol·g-1, hydroxyl groups content of Microsphere surface is 10.19 mmol·g-1, particle size mainly distributed in the 120μm150μm, micro-balls has no biological toxicity was found by the the cell toxicity test. The regularity of molecular chain is destructed by the cross-linking role of Starch molecular chain with N, N’-methylene bisacrylamide, which making intermolecular forces, hydrogen bond significantly weakened and resulting in the ability of starch crystallization reduced and stability of thermal increased.The adsorption properties to metal ions Cu2+, Co2+, Ni2+by the Mult-glucopyranose microsphere is discussesed firstly in the paper. At a low pH, the microsphere surface hydroxyl and acetyl-protonated by the protonation,,making an empty track on the proton is occupated by the oxygen atoms and lone pairs of electrons of nitrogen atoms, which reducing or lossing the coordination capacity of an empty track with the metal ion, especially the pH is lower than the point of zero charge on the microspheres surface, while, at a higher pH,, it is not easy to be adsorpted by be mult-glucopyranose microsphere hydrolysis because of the existing form of metal ions is changed by the strong of hydration The adsorption capacity of the three kinds of metal ions rapid by increased with the increasing concentration of metal ions in solution, but the adsorption rate of increase began to slow down as the concentration increased to a certain extent, and, adsorption capacity has no increase when reached a turning point, athletic ability of metal ions in aqueous solution enhanced, the polarization of coordination group on the Microsphere surface will increase as the temperature rising, which leading to relatively weakened the role of coordination and adsorption between Microsphere and metal ions, as well as adsorption capacity of Microsphere to metal ions declined; for another, the hydrolysis trend of metal ions is relatively more obvious as the temperature rise, which led to its being Microspheres Absorption capability is relatively weakened, the adsorption of metal ions by the Mult-glucopyranose microsphere decrease as the temperature increased,. at the beginning of the adsorption kinetics of metal ions by the microspheres, the metal ions are adsorbed rapidly on the outer surface of microspheres;, the metal ion concentration gradually decreased as the adsorption process, absorption rate is slower,which mainly controlled by diffusion,as the resistance is rising while metal ions spread to the internal pore along the micro-the ball; the adsorption has reached the equilibrium at the late phase reaction,in which adsorption mainly on the surface of the microspheres, and the drivers of concentration getting smaller and smaller. Langmuir isotherm equation and the Freundlich isotherm equation come up to the adsorption behavior of microspheres on the metal ions, it indicates that the adsorption of microspheres on metal ions is "preferential adsorption" process when the fitting of n is greater than 1 at different temperatures. Adsorption process is exothermic, lower temperatures favor adsorption, and the Mult-glucopyranose microsphere of metal ions mainly by physical adsorption enthalpy,ΔH is the main driving force for adsorption. The part impacted by the coordination of Microsphere is effected by the electron withdrawing of metal ions due to the impact of the coordination when metal ions is adsorpted, which resulting in cloud density of electron increases, so that the absorption peaks of vibrating infrared, crystal structure and thermal stability will change when metal ions is adsorpted by microsphere, and the linear relationship between change of the degree and adsorption capacity of the metal ions is proportional..After studying the Mult-glucopyranose microsphere on adsorption of metal ions, further studied the adsorption of the microspheres on organic compounds, such as phenol, tetrahydrofuran and pyridine. Mult-glucopyranose microsphere on the adsorption kinetics of organic compounds performance the characteristics of adsorption rate faster at the beginning, with the extension of adsorption time, adsorption rate was gradually reduced.The first-order adsorption kinetic equation and the second-order dynamic equations could fit all organisms in a Mult-glucopyra-nose microsphere on the adsorption kinetics, and had been relatively satisfied with the results, absorption was controlled by the film diffusion and particle during the process of proliferation. This also indicated that Mult-glucopyranose microsphere on the adsorption behavior of organic compounds existed in the physical factors and the chemical elements. Microspheres had good fitting on organic phenol, tetrahydrofuran, pyridine adsorption behavior and Langmuir equation and Freundlich equation.This noted that the Mult-glucopyranose microsphere on experimental adsorption behavior of three kinds of organic matter were consistented with Langmuir isotherm equation and the Freundlich isotherm equation, but comparised, the Freundlich equation has a better fitting degree for phenol and tetrahydrofuran, while the Langmuir equation for pyridine. And at different temperatures, the fitting of 1/n are less than 1, it indicated that microspheres on phenol, tetrahydrofuran, pyridine adsorption is a "preferential adsorption" process. And the adsorption was exothermic process, the lower of temperatures was favor for adsorption, and the Mult-glucopyranose microsphere on adsorption of organic compounds in order to envelope mainly. Enthalpy AH was the main driving force for adsorption. Microsphere adsorption of metal ions, due to the impact of the role of coordination, made Microsphere structure, the role of coordination occurred in part by the role of metal ions in electron impact, leading to electron cloud density increases, so that after Microsphere adsorption of metal ions the infrared absorption vibrations peaks, crystal structure and thermal stability will change,and the degree of change with the metal ions adsorption capacity was proportional to the linear relationship.It resulted that physical adsorption was major way of microspheres by adsorption behavior and thermodynamic function, the reasons of adsorption capacity of microspheres were higher specific surface area, higher pore volume and multi-glucopyranosyl ring structure. Microspheres absorded metal ions by pore, adsorbed organic by it’ smicrocavity. Mult-glucopyranose used it’s pore and microcavity to reach the aim of biphasic role of selective adsorption.更多还原