Generally, polymer networks created by controlled radical polymerization techniques (CRP) such as RAFT copolymerization of monomers with a suitable cross-linker are assumed to be more homogeneous than those made by free radical copolymerization (FRP). Our dynamic light scattering studies of PMMA gels in ?-Butyrolactone cast some doubt on this perception.Inhomogeneity was quantified as the static fraction of the total ensemble-averaged scattering intensity. This quantity does not differ strongly between RAFT and FRP gels, when gels with identical macroscopic properties (moduli) are compared (Figure 1).Furthermore, rheological and swelling experiments revealed that the cross-linking efficiency of RAFT gels decreases appreciably with increasing amount of RAFT agent and is significantly lower than that of FRP gels. This indicates a larger fraction of loops, dangling chains and possibly other imperfections in RAFT gels.

Investigation on the homogeneity of RAFT polymerized PMMA gels using dynamic light scattering and rheology

248th National Meeting (2014)

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