Study On Controlled/Living Photopolymerization Kinetics Of I-Butylmethacrylate In Microemulsion By NMP/ATRP Technique

Nitroxide mediated living radical photo polymerization has attracted considerable interest because of its reaction conditions are mild and as a living procedure in which control over molecular weight and macro molecular architecture can be achieved.In this paper, a new bifunctional initiators Br-HE-HMPP-Br was synthesized firstly. Controlled radical photopolymerization (CRPP) of i-butyl methacrylate (i-BMA) mediated by 2,2,6,6-tetramethyl-piperidinyl-l-oxyl(TEMPO) have been performed in anionic microemulsions. The kinetic mechanism of controlled/living free radical photopolymerization of i-BMA in microemulsion was studied. Copolmer of i-butyl methacylate and styrene was synthesized by CRPP of styrene, using Poly(i-BMA)-Br as macromolecular initiator. Using Br-HE-HMPP-Br as initiator, polyisobutylmethacrylate, Poly(i-BMA) obtained by Nitroxide Mediated Polymerization (NMP) in the microemulsion. The thiol fuctional Poly(i-BMA) was synthesized by thio end-functional of Poly(i-BMA)-Br.The main work and conclusions as follows:1. Using pyriding as a catalyst, a bifunctional initiator (Br-HE-HMPP-Br) was synthesized by the condensation of bromoacetyl bromide (BMB) with 2-hydroxy-l-[4-(2-hydroxyletho-xy)-phenyl]-2-methylpropan-l-one (Irgacure2959, HE-HMPP) in methylene dichloride (CH2Cl2).The structure of the product was characterized by element analysis, FTIR,1H NMR and UV-visible spectra.2. The phase diagrams of i-BMA/n-butanol/SDS-H2O system were described by visual and conductivity method. The variation in the phase bounder of microemulsion was measured by conductometer. The results show that the conductivity of microemulsion changed with increasing the aqueous phase, which indicated that the phase shift changed from W/O microemulsion through bicontinuous microemulsion to O/W microemulsion. In this paper, the O/W microemulsion was used.3. After selecting excellent experimental conditions, CRPP of i-BMA mediated by TEMPO have been carried out in anionic O/W microemulsion, using Br-HE-HMPP-Br as an initiator. The reaction kinetics of polymerization was studied. The results show that mnomer conversion increased linearly with time and the number-average molecular weight increased almost linearly with mnomer conversion, it is a kinetic character of controlled/living radical polymerization, and polymers exhibited narrow molecular weight distribution. The polymers were characterized by GPC,FTIR and 1H NMR. 4. Using Poly(i-BMA)-Br as an initiator, Polyisobutylmethacrylate-block-Polysty rene diblock copolymers were prepared by atom transfer free radical polymerization (ATRP) of styrene,. The polymers were characterized by GPC, 1H NMR, FTIR and TGA.5. Using Br-HE-HMPP-Br as an initiator, polyisobutylmethacrylate, Poly(i-BMA) obtained by Nitroxide Mediated Polymerization (NMP) in the microemulsion possess an bromine end-group that may be converted to other functional groups by appropriate chemical transformations. Here the bromine end-group of Poly(i-BMA) converted into an isothiounium salt by reaction with thiourea. Subsquent treatment of this salt with sodium hydroxide permits the cleavage to a thiol. The structure of thiol fuctional Poly(i-BMA) was characterized by 1H NMR,FTIR and GPC.