Baumgartner Saia, Kristl Julijana, Peppas Nicholas A
University of Ljubljana, Faculty of Pharmacy, Slovenia.
Pharm Res. 2002 Aug;19(8):1084-90. doi: 10.1023/a:1019891105250.
The purpose of this work was to investigate the swelling behavior of four cellulose ethers that differ in their type and degree of substitution and to elucidate the network structure of the swollen matrices under dynamic and equilibrium conditions.
Dynamic vapor sorption was performed to assess the ability of polymer chains and water molecules to interact. Dynamic and equilibrium swelling studies were performed to calculate molecular parameters of swollen polymers using the Flory-Rehner theory.
We determined the volume-swelling ratio of the polymer matrices and observed that it was dependent on their hydrophilicity. We determined molecular parameters that characterize the swollen hydrogels of cellulose derivatives, such as the polymer volume fraction in the swollen state, u2,S, the effective molecular weight of the polymer chain between physical entanglements, Me, the number of repeating units between two entanglements, u, and the number of entanglements per chain, e. The Me of the cellulose derivatives studied varied significantly depending on the type of cellulose ether and on the swelling time.
The order of mesh size, an important parameter for predicting drug diffusion and release, taking into account all determined parameters, is: hydroxypropyl cellulose < hydroxyethyl cellulose < hydroxypropyl methyl cellulose K100M < hydroxypropyl methyl cellulose K4M.
本研究旨在考察四种类型和取代度不同的纤维素醚的溶胀行为，并阐明在动态和平衡条件下溶胀基质的网络结构。
采用动态蒸汽吸附法评估聚合物链与水分子相互作用的能力。利用弗洛里－雷纳理论进行动态和平衡溶胀研究，以计算溶胀聚合物的分子参数。
我们测定了聚合物基质的体积溶胀率，发现其取决于聚合物的亲水性。我们确定了表征纤维素衍生物溶胀水凝胶的分子参数，如溶胀状态下的聚合物体积分数（u2,S）、物理缠结之间聚合物链的有效分子量（Me）、两次缠结之间的重复单元数（u）以及每条链的缠结数（e）。所研究的纤维素衍生物的Me因纤维素醚的类型和溶胀时间而异。
考虑到所有测定参数，预测药物扩散和释放的重要参数——网孔尺寸顺序为：羟丙基纤维素＜羟乙基纤维素＜羟丙基甲基纤维素K100M＜羟丙基甲基纤维素K4M。
