Pardubice, Czech Republic By Petr1888 (Own work) [CC-BY-SA-3.0] via Wikimedia Commons
High levels of acrylate in poly(methyl methacrylate), or PMMA, lead to formation of highly branched, compact macromolecules with ultra-high molar masses. The interaction of these short branches with column packing pores leads to abnormal (non-monotonic) elution in size-exclusion chromatography, resulting in poor separation and characterization by any means including viscometry or light scattering. In addition, these large polymers are subject to degradation by shear forces in the SEC column. Stepan Podzimek and co-authors show that separation by organic AF4 in tetrahydrofuran solvent overcomes the problems associated with SEC for PMMA, and permits accurate characterization of molar mass, size, conformation and branching ratio.
Podzimek, S.; Machotova, J.; Snuparek, J.; Vecera, M.; Prokupek, L. Journal of Applied Polymer Science 2014, 131, 40995. doi:10.1002/app.40995