Study On Preparation And Homogeneous Film-forming Properties Of Soluble Anion-exchange Polymer Based On Polystyrene

An indirect chloromethylation of linear polystyrene-b-polyethylene(PSE) was carried out first in a homogeneous system in this work, and then the cross-linking degree of chloromethylated PSE was measured. After evaluating the swelling degree of cross-linked anion-exchange polymer, suitable amination reagents and solvents were selected for preparing soluble anion-exchange polymer based on polystyrene. Various factors influencing the preparation of soluble anion-exchange polymer were investigated. Four kinds of soluble anion-exchange polymer were prepared, including trimethylamine anion-exchange polymer(TMA-AEP), triethylamine anion-exchange polymer(TEA-AEP), dimethylethanolamine anion-exchange polymer(DMEA-AEP), dimethylisopropanol anion-exchange polymer(DMIPA-AEP). Fourier transform infrared spectroscopy(FT-IR), hydrogen nuclear magnetic resonance('H-NMR), thermogravimetry analysis(TGA), differential scanning calorimetry (DSC) and other analysis were used to characterize the composition, structure and thermal stability of the products. The solubility of different kinds of soluble anion-exchange polymer in various solvents as well as the viscosity in methanol were measured. Their water adsorption rates and swelling ratios after flim forming were determined.The results showed that cross-linking degree of different chloromethylated PSE could be measured by solvent extraction combined with 1H-NMR spectroscopy. The cross-linking reaction led to the increase of the glass transition temperature of chloromethylated product, but the thermal decomposition of the chloromethyl groups occured more easily, resulting decrease of substitution degree. The cross-linked anion-exchange polymer swelled best in methanol, ethanol came second, among which, trimethylamine cross-linked anion-exchange polymer has the largest swelling degree,11.18 mL/g. Four prepared soluble anion-exchange polymer materials were totally soluble in methanol, but their thermal stability decreased after amination reaction, as in the following order:DMEA-AEP> DMIPA-AEP> TMA-AEP> TEA-AEP. The TMA-AEP had the largest solubility in methanol when ion-exchange capacity was 2.53 mmol/g. The higher substitution degree, the larger water adsorption ratio for the investigated soluble anion-exchange polymer materials. TEA-AEP had the largest water adsorption ratio as 10.0, and the film area could be 4.3 times larger after water adsorption.