Preparation Of Polymer Microspheres By Click Copolymerization Of Thiol And Isocyanate

Highly efficient and large scale fabrication of monodisperse microsphere free of any surfactant or additive remains a challenge.Among the state-of-art strategies,precipitation polymerization is unique because it does not need any surfactant or additive,a vital feature for applications of microspheres to bio-related fields.However,a low monomer loading(typically below 5 wt%),basically leading to poor yields,is an intrinsic hamper for large scale manufacturing process.Recently,click reactions have been applied to numerous research fields such as surface modification,bio-imaging,self-healing,drug discovery,and nanotechnology,etc.To the best of our knowledge,the combination of typical click reaction and precipitation polymerization has not been reported yet.1.Preparetion of thiourethane microspheres by precipitation polymerization.We introduce first combination of thiol-isocyanate click reaction and precipitation polymerization to allow the formation of micron-sized monodisperse microspheres at ambient temperature.This combination realizes the improvement of yield of polymer microspheres at as high as 30wt%monomer loading that is unprecedented in the research filed of precipitation polymerization.Another finding is that the microspheres are firstly found to show blue emission under UV irradiation without any addition of fluorescent agent.Thus,one can expect to find their applications to fluorescent biosensing in the coming future.We believe this process would be potential in rapid and efficient synthesis of uniform polymeric microspheres,owing to its mild condition,oxygen-tolerance,high monomer loading and high microsphere yield.2.Growth mechanism and application of thiourethane microspheres.The thiol concentration of thiourethane microspheres was determined by Ellman's reagent.The highest concentration of thiol obtained on microsphere surface was found to be 4.538?mol/g,when the ratio of thiol and isocyanate functional group was 1.5/1.The zeta potential of the microspheres in different solvent was characterized.When the thiol and isocyanate molar ratio was 1.5/1.0,the zeta potentials in acetonitrile and water were-0.47 V and-37.1 V,respectively.The thiourethane microspheres was used for modify filter paper and separation of oil-water emulsion,and the efficiency was up to 99.6%.3.Preparation of thiourethane porous polymers.Trithiocyanuric acid and toluene diisocyanate were used as monomers.The effect of solvent,temperature,and monomer loading were investigated.Result show that polymers can be prepared in DMSO with a yield of 88.7%.The copolymerization composition,pore structure and crystal structure of the thiourethane porous polymers were characterized.It was proved that the obtained polymer had an amorphous structure with a specific surface area of 62.6 m~2/g.