Synthesis Of Dihydroxyalkylpolysiloxanes And Study On Waterborne Polyurethanes Modified With Dihydroxyalkylpolysiloxanes

Polysiloxanes possess a variety of unique and superior properties such as low- temperature resistance, low surface energy, good water resistance, aging resistance, climate resistace and so on. Polysiloxanes can endow other polymers with the excellent properties so that new polymer materials can be obtained. In this thesis two different types of polysiloxanes were synthesized to modify waterborne polyurethanes and the properties of modified waterborne polyurethanes were simply studied.A series ofα-butyl-ω-N,N-dihydroxyethylaminopropylpolydimethylsiloxanes with molecular weight below 3000, which can form polyurethane-polysiloxane graft copolymer, were synthesized via hydroxyl protection, alkylation, hydrosilylation and deprotection using diethylolamine, Hexamethyldisilazane, 3-bromopropene as starting materials. The targeted product and intermediate products in each process had been fully characterized by FT-IR, GC, 1H NMR and LC-MS. The results showed that each step was successfully carried out and the targeted products were accessed in all cases.Another series ofα,ω-bis(3-(1-methoxy-2-hydroxyproxy)propyl) terminated polysiloxanes with molecular weight below 3000, which can form polyurethane- polysiloxane block copolymer, were synthesized via hydrosilylation, methoxylation and equilibrium reaction between allylglycidyl ether, tetramethyldisiloxane, trifluoro- methanesulfonic acid and octamethylcyclotetrasiloxane (D4). Hydrosilylation reaction was optimized and the process and the reaction time of methoxylation and D4 equilibrium reaction were determined.The anionic waterborne polyurethanes modified withα-butyl-ω-N,N-dihydroxy- ethylaminopropylpolydimethylsiloxanes andα,ω-bis(3-(1-methoxy-2-hydroxyproxy)- propyl) terminated polysiloxanes were prepared with toluene diisocyanate, polypropylene glycol, ethylene glycol, dimethylolpropionic acid and triehtylamine using acetone method. The viscosity of PSU latexes and the glosses, Shore hardness, tensile strength, elongation at break, solvent resistance and water resistance of the PSU films were studied. Experiments showed that hydroxyalkylpolysiloxanes can improve water resistance and solvent resistance of polyurethanes and the properties of graft modified polyurethanes are better than block modified polyurethanes.