Investigation on the homogeneity of PMMA gels synthesized via RAFT polymerization

Comparison of Polymer Networks Synthesized by Conventional Free Radical and RAFT Copolymerization Processes in Supercritical Carbon Dioxide

“…The solubilities of the components of the reacting mixture can be estimated from Flory's interaction parameter, χ, calculated using Equation (6). As mentioned earlier, if χ > 0.84, then the solute is soluble in scCO 2 [24].…”

RAFT thermoplastics from glycerol: a biopolymer for development of sustainable wood adhesives

“…The gelation suppression effect in controlled radical polymerizations (CRP) such as RAFT has been well-studied in systems with dilute multivinyl monomers, and more recently for systems comprised entirely of multivinyl monomers. [15][16][17] When a monomer with x vinyl groups is added to a propagating radical chain, (x − 1) vinyl groups remain that could further participate in initiation or propagation reactions, leading to intermolecular branches and intramolecular loop formation. Rather than immediately forming a pervasive polymer network at the early stages of polymerization, CRP promotes the formation of branched structures that only overlap to form a macrogel at monomer conversions far higher than classical gelation theory predicts.…”

Comparison of Thermoresponsive Hydrogels Synthesized by Conventional Free Radical and RAFT Polymerization

“…To be noted, the SR of G1R could be not evaluated because of the lack of gel consistency; we believe that this constitutes indirect evidence that non-defined chemical entanglement from side reactions (i.e., chain-chain crosslinking) contribute to the formation of gels by FRP; this explains the inability of RAFT to form gels at lower crosslinker feeds, simply because the reaction mechanism is more well-defined with a minimization of side-reactions [34] leading to better defined crosslinks overall and this is also corroborated by the difference between the SR of FRP and RAFT gels. RAFT polymerization allows for the incorporation of chemical crosslinks in a highly controlled manner, hence forming a well-defined hydrogel network [21,22,23,24,25,26]. Finally, after 24 h, the temperature was increased to 37 °C, and the SR of each gel instantly dropped to 1 due to the loss of PNIPAAm solubility in water above 32 °C.…”

“…More particularly, RAFT polymerization [18,19,20] has been used to copolymerize (di-)vinyl monomers to form more homogeneous and structurally well-defined three-dimensional (3D) networks that are difficult, if not impossible, to obtain via the conventional FRP route [19,21]; these networks find numerous applications as swelling matrices, cell/drug encapsulants, separation technologies, self-healing materials, and responsive sensors and actuators. Recently, several groups reported on the macroscopic differences between RAFT and FRP-made polymer networks [21,22,23,24,25,26]; it is generally accepted that FRP networks tend to produce less well-defined polymer meshes with collapsed micro-domains, which in turn compromise the (de-)swelling or responsive properties of the bulk materials macroscopically. Conversely, RAFT produced gels with narrow polymer mesh distributions with very good control on the polymerization kinetics.…”