Bell C L, Peppas N A
Biomedical Materials Laboratory, School of Chemical Engineering, Purdue University, West Lafayette, IN 47907-1283, USA.
Biomaterials. 1996 Jun;17(12):1203-18. doi: 10.1016/0142-9612(96)84941-6.
Grafted poly (methacrylic acid-g-ethylene glycol) [P(MAA-g-EG)] copolymers were synthesized and their pH sensitivity was investigated. P(MAA-g-EG) membranes showed pH sensitivity due to complex formation and dissociation. Uncomplexed equilibrium swelling ratios were 40 to 90 times higher than those of the complexed states and varied according to copolymer composition and poly(ethylene glycol) (PEG) graft length. Mesh sizes in the two states were determined. Swelling under oscillatory pH conditions revealed the dynamic sensitivity of P(MAA-g-EG) membranes as well as the diffusional mechanisms causing network expansion and collapse. Network collapse (complexation) occurred more rapidly than network expansion (decomplexation). A Boltzmann superposition model was used to analyse this behaviour. Mechanical testing was used to evaluate the strength of P(MAA-g-EG) membranes and to elucidate the mesh size under various conditions. Solute diffusion coefficients were higher in uncomplexed than in complexed P(MAA-g-EG) membranes and decreased as solute size increased. Lower diffusion coefficients were observed with membranes or hydrogels containing longer PEG grafts, since in the uncomplexed state the PEG grafts dangled into the polymer mesh space. Membrane permeability was responsive to changing pH conditions, and separation of solutes was achieved.
合成了接枝聚（甲基丙烯酸 - g - 乙二醇）[P（MAA - g - EG）]共聚物，并研究了其pH敏感性。P（MAA - g - EG）膜由于络合物的形成和解离而表现出pH敏感性。未络合状态下的平衡溶胀比是络合状态下的40至90倍，并根据共聚物组成和聚乙二醇（PEG）接枝长度而变化。测定了两种状态下的网孔尺寸。在振荡pH条件下的溶胀揭示了P（MAA - g - EG）膜的动态敏感性以及导致网络膨胀和塌陷的扩散机制。网络塌陷（络合）比网络膨胀（解络合）发生得更快。使用玻尔兹曼叠加模型分析这种行为。通过力学测试评估P（MAA - g - EG）膜的强度，并阐明各种条件下的网孔尺寸。未络合的P（MAA - g - EG）膜中溶质扩散系数高于络合状态，且随着溶质尺寸的增加而降低。含有较长PEG接枝的膜或水凝胶观察到较低的扩散系数，因为在未络合状态下PEG接枝悬垂到聚合物网孔空间中。膜渗透性对变化的pH条件有响应，并实现了溶质的分离。
