Layer-by-layer Assembly Of Four Neutral Polymers In Organic Solvents And Solubility Of The Multilayer Films

In the past two decades, layer–by–layer (LbL) assembly has become a veryeffective method for fabricating multilayer films with controlled architecture andcomposition. LbL assembly can be driven by some non-covalent interactions,including electrostatic interactions, hydrogen–bonds, halogen–bonds, andcharge–transfer interactions.LbL films are rarely fabricated in organic solvents. However, LbL assembly inorganic solvents has some advantages compared with that in aqueous solution.(1)Those substances which are water insoluble or react with water could be assembledwith LbL assembly in organic solvents.(2) If a water–soluble substance can not beassembled with LbL assembly in water, it might be assembled in some organic solvent.LbL assembly of two water–soluble polymers assembled in organic solvents has notbeen reported. In the paper, water–soluble polymers were taken as building blocks,LbL films were fabricated in several organic solvents, and the solubility of themultilayer film in water was studied. In addition, the solubility and dissolutionmechanism of two hybrid films in water was also explored. The main results weredescribed below.In Chapter2，water–soluble polymers including poly (N–vinylcaprolactam)(PVCL), poly(N–vinylpyrrolidone)(PVPON) and poly(2–hydroxypropyl acrylate)(PHPA) were taken as building blocks. PVCL/PHPA and PVPON/PHPA films werefabricated in butanone solutions. The successful fabrication of PVPON/PHPA films inorganic solvents solved the problem that their multilayer film was difficult to beassembled in water. According to solubility of PVCL/PHPA and PVPON/PHPA filmsin dozens of organic solvents, the Hansen solubility parameters (HSP) of multilayerfilms were obtained with HSPiP software. The dissolution of PVCL/PHPA film andPVPON/PHPA film in water was studied. The dissolution of PVCL/PHPA filmdepended on water temperature. The PVPON/PHPA film was water-soluble and wasnot temperature-responsive.In Chapter3, poly(2–hydroxypropyl methacrylate)(PHPMA) is a water-insoluble polymer, PVCL/PHPMA film was fabricated in butanone solutions.PVPON/PHPA/PVCL hybrid film and PHPMA/PVCL/PHPA hybrid film werefabricated on the basis of different solubility of PVCL/PHPA film, PVCL/PHPMAfilm, and PVPON/PHPA film. It was found that the dissolution process ofPVPON/PHPA/PVCL hybrid film could be divided into two steps，and the solubilityin second step was similar with a PVCL/PHPA film. FT–IR spectra ofPVPON/PHPA/PVCL hybrid film dissolved in water at45°C indicated that PVPONand PHPA were dissolved firstly. The dissolution process of PHPMA/PVCL/PHPAhybrid film was also divided into two steps. PVCL and PHPA in the hybrid film weredissolved in the first step, the dissolution temperature was lower than that of aPVCL/PHPA film. PVCL was partially dissolved in second step. Introduction ofPHPMA into PVCL/PHPA film can be used as an effective method to control the filmdissolution.