Authors: Susan Arco, Eduardo Atayde Jr., Caidric Gupit and Mark Neil Tolentino
The synthesis of polymers designed to imitate the chemistry behind naturally–occurring polymers is only a recently emerging field of research. Their most notable feature involves reversible transitions in response to external stimuli, like temperature and pH. In this study, thermo–responsive homopolymers of poly(ethylene glycol) methyl ether methacrylate (PEGMA) and di(ethylene glycol) methyl ether methacrylate (DEGMA), and their corresponding block copolymers with methacrylic acid (MAA) were synthesized via the reversible addition-fragmentation chain transfer (RAFT) polymerization technique. Data from gel permeation chromatography showed increasing molecular weight and polydispersity index (PDI) with increasing monomer feed ratio. The low PDI justified the method’s great control over the polymerization process. Structural characterization with infrared spectroscopy and proton nuclear magnetic resonance then demonstrated the success of RAFT polymerization. This was supported by morphological changes before and after copolymerization, as observed using atomic force microscopy. Lastly, the lower critical solution temperature (LCST) was investigated through ultraviolet–visible light spectroscopy and dynamic light scattering. General observations suggested efficient LCST tailoring by varying the molar feed ratios. These results show the efficiency and versatility of RAFT polymerization in the synthesis of thermo–responsive polymers, with their promising applications in the fields of sensors and biotechnology.
Keywords: RAFT polymerization; Thermo–responsive polymers; Ethylene glycol derivatives; LCST; Biotechnology