State Key Laboratory of Supramolecular Structure and Materials, Jilin University, Changchun 130012, China.
Langmuir. 2012 Feb 7;28(5):2704-9. doi: 10.1021/la2045042. Epub 2012 Jan 19.
We fabricated a layer-by-layer (LbL) film of temperature-responsive homopolymers at neutral pH and studied its temperature-dependent solubility. We first measured the cloud point of mixed solutions of temperature-responsive polymers. The significant decrease of cloud point suggested that the intermolecular interaction between two polymer chains of different kinds was stronger than that between two polymer chains of the same kind. Strong intermolecular interaction between two polymer chains of different kinds is a prerequisite for LbL assembly. On the basis of the decrease of cloud point of mixed solutions of temperature-responsive homopolymers, we selected poly(N-vinylcaprolactam) (PVCL) and poly(2-hydroxypropyl acrylate) (PHPA) for LbL assembly. LbL films of the two polymers were fabricated at neutral pH at a constant temperature. When the film was immersed in purified water at a temperature lower than the assembly temperature, it can be partially dissolved with a diffusion-limited dissolution process. The temperature-responsive solubility of the LbL film is closely connected to the phase behavior of mixed solutions of the two polymers. Additionally, as compared to multilayer films of neutral polymers and poly(carboxylic acid)s, the PVCL/PHPA multilayer film is relatively stable when it was immersed in buffer solutions near physiological pH at the assembly temperature. Such LbL films with temperature-responsive solubility might be used as a dissolvable film or a smart capsule.
我们在中性 pH 值下制备了温度响应均聚物的层层（LbL）薄膜，并研究了其温度依赖性溶解度。我们首先测量了温度响应聚合物混合溶液的浊点。浊点的显著降低表明，两种不同类型的聚合物链之间的分子间相互作用比两种相同类型的聚合物链之间的分子间相互作用更强。两种不同类型的聚合物链之间的强分子间相互作用是 LbL 组装的前提。基于温度响应均聚物混合溶液浊点的降低，我们选择了聚（N-乙烯基己内酰胺）（PVCL）和聚（2-羟丙基丙烯酸酯）（PHPA）用于 LbL 组装。在恒定温度下，在中性 pH 值下制备了两种聚合物的 LbL 薄膜。当薄膜在低于组装温度的纯化水中浸泡时，它可以通过扩散限制的溶解过程部分溶解。LbL 薄膜的温度响应溶解度与两种聚合物混合溶液的相行为密切相关。此外，与中性聚合物和聚（羧酸）的多层膜相比，当在组装温度下将 PVCL/PHPA 多层膜浸入接近生理 pH 的缓冲溶液中时，其相对稳定。这种具有温度响应溶解度的 LbL 薄膜可用作可溶解膜或智能胶囊。
