THE USE OF POLYSACCHARIDES EXTRACTED FROM SEED OF Persea americana var. Hass ON THE SYNTHESIS OF ACRYLIC HYDROGELS

This paper reports the use of polysaccharides extracted from seed of Persea americana var. Hass in the synthesis of acrylic hydrogels. The effects of the chemical composition (acrylamide/acrylic acid), the concentration of crosslinking agent (glycerol diacrylate) and the type of initiation (redox, photoinitiation) of the hydrogels were evaluated with and without polysaccharides. Xerogels were characterized by FTIR spectroscopy, differential scanning calorimetry (DSC) and scanning electron microscopy (SEM), while for the swollen hydrogels the swelling kinetic and mechanical properties were evaluated. The kinetic parameters were obtained using the second order equation proposed by Schott, where it is reported that by increasing the concentration of the crosslinking agent, the degree of swelling is reduced because of the greater structural level. The increase of the amount of acrylamide and the amount of polysaccharides causes also a decrease in the swelling degree. The type of initiation also affected the hydrogels swelling kinetic, the photoinitiated hydrogels were the ones that captured less water. Moreover, the increasing of the glass transition temperature and the compression modulus with the crosslinking agent concentration and molar ratio AAm/AAc are observed for hydrogels with and without polysaccharides. The results demonstrate a successful incorporation of polysaccharides into the polymeric network.

本论文报道了以哈斯鳄梨（Persea americana var. Hass）籽中提取的多糖合成丙烯酸水凝胶（acrylic hydrogels）的研究工作。本研究分别在添加与未添加多糖的体系中，考察了水凝胶的化学组成（丙烯酰胺/丙烯酸，acrylamide/acrylic acid）、交联剂（甘油二丙烯酸酯，glycerol diacrylate）浓度以及引发方式（氧化还原引发、光引发，photoinitiation）对其性能的影响。研究采用傅里叶变换红外光谱（FTIR spectroscopy）、差示扫描量热法（DSC）与扫描电子显微镜（SEM）对干凝胶（xerogels）进行表征；针对溶胀状态的水凝胶，则测试了其溶胀动力学与力学性能。动力学参数通过肖特（Schott）提出的二级方程计算得到，结果显示：随着交联剂浓度升高，水凝胶的溶胀度会因凝胶结构致密性提升而降低。丙烯酰胺用量与多糖添加量的增加同样会导致溶胀度下降。引发方式同样会影响水凝胶的溶胀动力学性能，其中光引发制备的水凝胶吸水率最低。此外，无论是否添加多糖，随着交联剂浓度以及丙烯酰胺与丙烯酸的摩尔比（AAm/AAc）升高，水凝胶的玻璃化转变温度（glass transition temperature）与压缩模量（compression modulus）均会上升。本研究结果证明，多糖已成功被引入聚合物网络结构中。