SOLUTE AND PENETRANT DIFFUSION IN SWELLABLE POLYMERS .2. VERIFICATION OF THEORETICAL-MODELS
SOLUTE AND PENETRANT DIFFUSION IN SWELLABLE POLYMERS .2. VERIFICATION OF THEORETICAL-MODELS
复制标题
DOI：
10.1002/polb.1986.090240215
复制
发表时间：
1986-02-01
影响因子：
--
通讯作者：
PEPPAS, NA
中科院分区：
文献类型：
--
作者：
KORSMEYER, RW;VONMEERWALL, E;PEPPAS, NA
建立了一个描述渗透剂和溶质在可膨胀聚合物板中扩散的数学模型，应用于装载可溶药物的亲水聚合物的情况，其中渗透剂（水）被吸附，溶质（药物）被解吸。选择了渗透剂和溶质扩散系数与渗透剂浓度的指数依赖关系，并证明该关系足以描述所研究的体系。用2‐甲基丙烯酸羟乙酯（HEMA）和n‐乙烯基‐2‐吡咯烷酮（NVP）共聚物对模型进行了实验验证。用过氧化苯甲酰引发剂对单体进行本体聚合，并切成薄片。共聚物中HEMA单体摩尔分数分别为0.707、0.446和0.211。在37°C和0°C的水中观察了样品的膨胀行为。制备了含溶质样品，并通过监测释放介质的紫外吸收来跟踪溶质从这些样品释放到水中。采用脉冲梯度自旋回波核磁共振技术研究了凝胶中水和三氟乙酸钠、七氟丁酸钠两种模型溶质的扩散系数与浓度的关系。该技术测量的扩散系数符合自由体积理论预测的浓度依赖性。模型中使用的简单指数依赖关系是对瞬态扩散实验中这种行为的充分近似。
A mathematical model developed to describe diffusion of a penetrant and a solute in a swellable polymer slab was applied to the case of a hydrophilic polymer loaded with a soluble drug in which the penetrant (water) is sorbed and solute (drug) is desorbed. An exponential dependence of the penetrant and solute diffusion coefficients on penetrant concentration was chosen and shown to be adequate for description of the systems studied. Experimental verification of the model was conducted by using copolymers of 2‐hydroxyethyl methacrylate (HEMA) andN‐vinyl‐2‐pyrrolidone (NVP). The monomers were bulk polymerized with benzoyl peroxide initiator and cut into thin disks. Monomer mole fractions of HEMA in the copolymers were 0.707, 0.446, and 0.211. Swelling behavior of the samples was observed in water at 37 and 0°C. Solute‐containing samples were prepared and solute release from these samples into water was followed by monitoring the UV absorption of the release medium. The concentration dependence of the diffusivity of water and two model solutes, sodium trifluoroacetate and sodium heptafluorobutyrate, in the gels was studied by using the pulsed‐gradient spin‐echo NMR technique. The diffusivities measured by this technique followed the concentration dependence predicted by the free‐volume theory. The simple exponential dependence used in the model was an adequate approximation of this behavior in the case of a transient diffusion experiment.