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Solvent and temperature effects in PI-RAFT polymerisation of PEG methacrylate
A recent study shows how solvent choice and temperature directly influence the PI-RAFT polymerisation of PEG methacrylate – a crucial step towards controllable, biocompatible polymers.
Photoiniferter (PI)-RAFT polymerisation is a promising strategy to produce (meth)acrylic and styrenic polymers with a highly ‘living’ character, avoiding bimolecular termination common in conventional RAFT. A team has now studied the polymerisation of poly(poly(ethylene glycol) methyl ether methacrylate) (P(PEGMA)) under different conditions.
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Solvent selection as key factor
The study investigated excitation wavelengths, monomer concentrations, temperatures and solvents. Results showed that the propagation constant (kp) is mainly governed by the RAFT main equilibrium. Arrhenius parameters, activation enthalpy and entropy were determined for various solvents.
Regression analyses revealed a strong correlation between the collision factor A and the extinction coefficients of the chain transfer agents (CTAs). Polarity scales like Kalmet–Abraham–Taft (KAT) proved unreliable predictors. A chain transfer constant (Ctr) above 1 indicated good control; Ctr decreased with increasing temperature. Anisole was the most suitable solvent, maintaining Đ = 1.30 even at 40 °C.
Source: Chang et al., Polymer Chemistry, Issue 25, 2025
