Thermo and pH-Responsive Poly(DEGMA-co-OEGMA)-b-Poly(DEAEM) Synthesized by RAFT Polymerization and Its Self-Assembly Study

Drug delivery and release systems using stimuli-responsive nanostructures based on amphiphilic copolymers have gained great importance. In this work copolymers from oligo(ethylene glycol) methyl ether methacrylate (OEGMA) and di(ethylene glycol) methyl ether methacrylate (DEGMA) as thermo-responsive moiety and block copolymers incorporating N,N′ -diethylaminoethyl methacrylate (DEAEM) as pH-responsive one, were synthesized by reversible addition-fragmentation chain transfer polymerization (RAFT) using 5-amino-4-methyl-4-(propylthiocarbonothioylthio)-5-oxo pentanoic acid as chain transfer agent (CTA). The number average molecular weights ( M n ), and dispersity Đ confirmed a good RAFT control. Polymers were characterized by Fourier transform infrared spectroscopy using a attenuated total reflection (FTIR-ATR), nuclear magnetic resonance (NMR), gel permeation chromatography (GPC), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), dynamic light scattering (DLS), transmission electron microscope (TEM), and Turbidimetry. Their self-assembly behavior is described by its hydrodynamic diameter ( D h ), its ζ -potential and as well as its cloud point temperature ( T cp ). The results showed thermo-responsive and pH-responsive systems with T cp in phosphate-buffered saline (PBS) pH=7.4 around 37 and 42 °C the isoelectric point was found in a pH range between 7.0 and 7.5, further the critical micelle concentration (CMC) indicated very low values between 5.85 to 4.20 × 1(0 −4 mg ml/ −1 . The developed block copolymeric systems have potential to be used for drug transport and delivery.