In-situ Monitor The Synthesis Of Methacrylates Polymers Via An ARGET ATRP

Amphiphilic copolymer poly(hydroxyethyl methacrylate-co-tert-butyl methacrylate)[P(HEMA-co-tBMA)] was synthesized by activators regenerated by electron transfer atomtransfer radical polymerization (ARGET ATRP), and the synthesis process was monitored byin-situ infrared spectroscopy (IR). The molecular weights, chemical structures andcharacteristics of the copolymer were confirmed by1H NMR, GC, and GPC. The molecularweights of the polymer with narrow molecular weight distributions (Mw/Mm<1.50) increasedapproximately linearly with the monomer conversion, indicating a good control ofpolymerization. The influences of various parameters on the living polymerization wereexplored. The reaction temperature ranged from50℃-90℃and the best temperature alongwith high conversion was60℃. The tBMA conversion rate decreased gradually with theincrease of tBMA content, while the HEMA conversion rate was almost not affected by theHEMA content. The weak polar solvent was more favorable to the polymerization comparedto polar solvent. The molar ratio of the reducing agent to catalyst had an important effect onthe polymerization and increasing the amount of reducing agent would accelerate the reactionrate but cause wider molecular weight distributions. All these results indicated that in-situ IRmonitoring the polymerization process contributed to a more in-depth understanding of themechanism of the copolymerization of methyl acrylate monomers, and established thetheoretical and technological foundation of the development and clinical application of suchpolymerization.One-pot combination of ARGET ATRP and ring opening polymerization (ROP) wasused to synthesize amphiphilic copolymer poly(hydroxyethylmethacrylate)-g-poly(-caprolactone)(PHEMA-g-PCL), and synthesis process was monitoredby in-situ infrared spectroscopy. The reaction conversion and reaction end point wereconfirmed by monitoring the transformation condition of HEMA. The molecular and structureof PHEMA and PHEMA-g-PCL were characterized by1H NMR and GPC. The researchresults indicated that one-pot strategy has gained polymers PHEMA-g-PCL with controllablemolecular weights and narrow molecular weight distributions, and reduced the steps ofreaction and purification.