Synthesis of hydrogels of cellulose acetate (AC) cross-linked with 3,3', 4,4' benzophenonetetracarboxylic dianhydride (BTDA): characterization and adsorption physicochemical study
Synthesis of hydrogels of cellulose acetate (AC) cross-linked with 3,3', 4,4' benzophenonetetracarboxylic dianhydride (BTDA): characterization and adsorption physicochemical study
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DOI：
10.1590/s0104-14282009000400006
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发表时间：
2009-01-01
期刊：
影响因子：
--
通讯作者：
Oliveira, Victor A.
中科院分区：
文献类型：
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作者：
Botaro, Vagner R.;Santos, Cláudio G.;Oliveira, Victor A.
本工作描述了标称取代度DS = 2.5的乙酸纤维素（AC）与3，3 '，4.4'二苯甲酮四羧酸二酐（BTDA）交联的水凝胶的合成。通过热分析（TG/DTG）和傅里叶变换红外光谱（FTIR）对原料进行了表征。通过用已知量的标准NaOH溶液滴定来测定乙酸纤维素的DS。BTDA水凝胶的合成与0.5，0.75和1.0摩尔的BTDA/摩尔的AC。FTIR被证明是监测反应过程和纯化进展的合适方法。紫外-可见光谱和分析证实了游离羟基的酯化。通过扫描电镜（SEM）分析交联反应后AC结构的表面改性，并通过BET法测定水凝胶的密度和孔隙率。研究了二酐浓度对凝胶形成所需时间的影响。还记录了交联度增加对材料热行为的影响。得到了不同网络化剂和网络化度的水凝胶I在不同温度下的吸水等温线。Arrhenius方程用于确定不同水凝胶在不同温度下的扩散系数和溶胀过程的阈值能量。通过测量不同温度下平衡时的最大吸水量，用Gibbs/Helmholtz方程确定混合物的焓。
This work describes the synthesis of hydrogels of cellulose acetate (AC), with a nominal degree of substitution DS = 2.5, cross-linked with 3,3',4.4' benzophenonetetracarboxylic dianhydride (BTDA). The raw materials were characterized by thermal analysis (TG/DTG) and by Fourier transform infrared spectroscopy (FTIR). DS of cellulose acetate was determined by titration with a known amount of standard NaOH solution. Hydrogels of BTDA were synthesized with 0.5, 0.75 and 1.0 mol of BTDA/mol of AC. FTIR proved to be a suitable method to monitor the course of reactions and the progress of purification. UV-vis spectroscopy and analysis confirmed the esterification of the free hydroxyl groups. Surface modification of AC structure after the cross-linking reaction was analyzed by Scanning Electron Microscope (SEM) and density and porosity of the hydrogels were determined by BET. The influence of the concentration of dianhydride on the time necessary for formation of the gel was investigated. The influence from the increase in the degree of cross-linking on the thermal behavior of the material was also documented. Water absorption isotherms were obtained for hydrogels I with different reticulating agents and reticulation degrees at different temperatures. The Arrhenius equation was used to determine the diffusion coefficient of the different hydrogels at distinct temperatures and the threshold energy for the swelling process. The enthalpy of mixture was determined through the measurement of the maximum quantity of water absorbed at equilibrium at different temperatures, with the Gibbs/Helmholtz equation.