In-situ IR Monitoring the Synthesis of Amphiphilic Copolymery P(HEMA-co-tBMA) via ARGET ATRP

The amphiphilic copolymer poly(hydroxyethyl methacrylate-co-tert-butyl methacrylate) [P(HEMA-co-tBMA)] was synthesized by activators regenerated by electron transfer atom transfer radical polymerization (ARGET ATRP), with the synthesis process monitored by in-situ infrared spectroscopy (IR). The molecular weight, chemical structure and characteristics of the copolymer were determined by 1H NMR, gas chromatography and gel permeation chromatography. The influences of various parameters on the living polymerization were explored. The molecular weight of the copolymer with narrow molecular weight distribution (Mw/Mn < 1.50) increases approximately linearly with the monomer conversion, indicating a good control of polymerization. In the reaction temperature range from 50 °C to 90 °C, the monomer conversion is higher at 60 °C. The tBMA conversion rate decreases gradually with the increase of tBMA content, while the HEMA conversion is hardly affected by HEMA content. Weak polar solvent is more favorable to the polymerization compared to polar solvent. The molar ratio of reducing agent to catalyst has significant effect on the polymerization and increasing the amount of reducing agent will accelerate the reaction rate but causes wider molecular weight distribution. It is indicated that in-situ IR monitoring contributes to a more in-depth understanding of the mechanism of methacrylate monomer copolymerization.

The amphiphilic copolymer P(HEMA-co-tBMA) was synthesized by ARGET ATRP. With monitoring by in-situ infrared spectroscopy (IR), the reaction kinetics and mechanism of the copolymerization of hydrophilic HEMA/hydrophobic tBMA monomers are systematically investigated, which will provide the guidance for copolymerization of P(HEMA-co-tBMA) and this kind of hydrophilic/hydrophobic monomers.Figure optionsDownload as PowerPoint slide