【作者】 徐丹；

【导师】 郭丽萍；

【作者基本信息】 武汉理工大学 ， 无机化学， 2012， 硕士

【摘要】 由于非体积效应的存在,以单分散非聚电解质为标样建立的凝胶渗透色谱测定聚电解质的分子量及分布的方法存在误差,为了解决这一问题,本文通过一系列方法制备了凝胶渗透色谱用聚甲基丙烯酸标样,研究工作具体包括以下几点：(1)提出了一种酯类水解的方法,结果表明,将聚甲基丙烯酸甲酯(PMMA)标样配成10%的1,4-二氧六环溶液,在氮气氛保护下,加入KOH甲醇溶液回流水解24小时,蒸干溶剂后继续在1mol/L NaOH水溶液中回流水解24小时,其水解率接近99%。(2)以甲苯为良溶剂,石油醚为沉淀剂,通过等温沉淀分级将PMMA粗产品分级成6个窄分布的标样,所得PMMA标样分子量分布均匀,分级效率较好。将自制PMMA标样逐个水解为聚甲基丙烯酸(PMAA)标样,GPC分析显示自制PMAA标样峰形对称,分散系数小,分子量分布均匀,适用于PMAA及其衍生物类分子量的测定。(3)以甲醇为良溶剂,乙醚为沉淀剂,通过等温沉淀分级将PMAA粗产品分级成5个窄分布的标样,随后利用二氯亚砜先酰氯化再醇解的方法,将自制窄分布PMAA酯化为PMMA,由PMMA标样分子量计算自制]PMAA标样分子量及分布,用乌氏粘度计对粘均分子量的计算值进行检验,两者的相对误差不超过10%。GPC分析显示自制PMAA及PMMA标样峰形对称,峰窄,且分子量分布均匀。(4)研究发现,聚丙烯酸(PAA)与PMAA测定四种不同类型聚羧酸减水剂的分子量及分布的结果误差基本小于20%,但非电解质标样聚乙二醇(PEG)与PMAA标样的测定结果却相差甚远,表明了非聚电解质标样在测定聚电解质的分子量及分布时会带来很大的误差。光散射的测定值与以自制PMAA为标样的GPC测定结果误差不超过20%,再次证明了本文建立的通过自制聚电解质标样测定聚羧酸减水剂分子量及分布的方法是可靠的。更多还原

【Abstract】 Due to the presenced of non-volume effect, when used monodisperse non-polyelectrolyte as standards, the method of determination of molecular weight and distribution of the polyelectrolyte by GPC presenced errors. To solve this problem, we prepared polymethylacrylic acid standard samples for GPC calibration through series of methods. The research including the following:(1) Proposed an method of ester hydrolysis, the results showed that dubbed poly (methyl methacrylate)(PMMA) standard samples in10%dioxane solution, reflux hydrolyzed24hours in KOH methanol solution under the protection of nitrogen atmosphere, evaporated solvent and continued to reflux hydrolysis24hours in1mol/L NaOH aqueous solution, the degree of hydrolysis could be reached99%.(2) Uesed toluene as good solvent, petroleum ether as the precipitant, through isothermal precipitation grading, PMMA crude products were graded into six narrow distribution standard samples with molecular weight in3.1X103～4.3X104. The obtained PMMA standard samples molecular weight distributed evenly and had good grade efficiency. Individually hydrolyzed self-made PMMA standard samples to PMAA samples, GPC analysis showed the self-made PMAA sample peak shape and symmetry, the dispersion coefficients were small, they could be applied to determinate the molecular weight and distribution of PMAA and its derivatives.(3) Used methanol as good solvent, ethyl ether as precipitating agent, the PMAA crude products were graded into five narrow distribution standards by isothermal precipitation grading.With self-made narrow distribution PMAA as raw materials for esterification, using thionyl chlorided and alcohol decomposed to get narrow distribution of PMMA. The molecular weight of obtained PMMA samples were in the range of2.97x103-3.63x104, molecular weight distribution coefficient were less than2, GPC analysis showed the peak of self-made PMAA and PMMA standard samples were symmetrical and narrow, molecular weight distribution were evenly. The viscosity average molecular weight values by calculating were tested by Ubbelohde viscometer,the relative error did not exceed10%, proved that the method preparing PMAA samples in this paper was feasible, and the molecular weight values were accurate and reliable.(4) The study found that,when used polyacrylic acid (PAA) and PMAA respectively to determinate molecular weight and distribution of four different types of polycarboxylate superplasticizers, the error were less than20%, but the determination results of non-electrolyte standard polyethylene glycol (PEG) and PMAA samples falls far short, which indicating non-polyelectrolyte standards will bring significant errors in the determination of molecular weight and distribution of the polyelectrolyte. The error between the determination results by light scattering and GPC measurements results by self-made PMAA as standards were less than20%, proved that determination of molecular weight and distribution of polycarboxylate superplasticizer by self-made polyelectrolyte standards was reliable.更多还原