Synthesis and characterization of amphiphilic Poly(2-hydroxyethyl acrylate-g-α-Methyl-β-Alanine) by Nitroxide-Mediated Polymerization Using “grafting through” approach

Abstract

Oligomeric poly(α-methyl-β-alanine)with vinyl end-group (PmBA) was synthesized via base-catalyzed hydrogen-transfer polymerization (HTP) of molten methacrylamide (MAm) in the presence of sodium tert-butoxide (t-BuONa). The PmBA was used as a comonomer in the synthesis of amphiphilic poly(2-hydroxyethyl acrylate-g-α-methyl-β-alanine) (PHEA-g-PmBA)via nitroxide-mediated polymerization (NMP)and "grafting through" approach.The graft copolymer formation was confirmed byproton nuclear magnetic resonancespectroscopy (1H-NMR), Fourier-transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and static light scattering (SLS)measurements. Thermogravimetric analysis of the amphiphilicPHEA-g-PmBAexhibited a multi-step decomposition curve corresponding to the α-methyl-β-alanine and the 2-hydroxyethyl acrylate blocks at about 306, 369, and 403 °C.DSC curve of the copolymer has a baseline shift at −12.87 °C attributed to the glass transition temperature. SLS analysis of the final product resulted in a weight average molecular weight of 83.6 kDa. The spectroscopic and thermal analyses proved that amphiphilicPHEA-g-PmBA was successfully synthesized through HTP and NMP.