Triphenylphosphine-Containing Thermo-Responsive Copolymers: Synthesis, Characterization and Catalysis Application

Triphenylphosphine-containing thermo-responsive copolymers of 4-(diphenylphosphino) styrene (DPPS), di(ethylene glycol) methyl ether methacrylate (DEGMA) and oligo(ethylene glycol) methyl ether methacrylate (average molecule weight is 300, OEGMA 300 ) were synthesized by free-radical copolymerization using azodiisobutyronitrile (AIBN) as an initiator in solution polymerization. A series of copolymers P(DEGMA- co -DPPS- co -OEGMA 300 ) with different lower critical solution temperature (LCST) were synthesized. The synthesized copolymers were well characterized by 1 H NMR, 31 P NMR and gel permeation chromatography (GPC). Based on the copolymers, a thermo-responsive and water soluble assembled catalyst of palladium acetate was developed. In the presence of the thermo-responsive copolymer-supported palladium catalyst, the Suzuki-Miyaura reaction proceeded efficiently in water. The catalyst was reused at least five cycles without obvious decrease in catalytic activity and can be easily recovered by heating/centrifugation of the polymer aqueous solution.