Initiator-dependent kinetics of lyotropic liquid crystal-templated thermal polymerization

Abstract

In this study, we examine the polymerization kinetics with different thermal initiators in lamellar and hexagonal lyotropic liquid crystal (LLC) structures directed by Pluronic L64. Ammonium persulfate is used to initiate the polymerization from the water phase, whereas azobisisobutyronitrile and benzoyl peroxide are employed to commence the reaction through the monomer phase. While the mesophase structure remains intact for all the initiation systems, the kinetics of polymerization and conversion vary significantly. The obtained differential scanning calorimetry (DSC) results reveal that, under the same conditions, the initiation from water (IFW) system results in enhanced reaction rates as well as higher monomer conversions compared to the initiation from oil (IFO) system. A higher termination rate in LLC nanoconfinements induces lower reaction rates in the IFO system. Moreover, our work on different LLC structures shows that the effect of nanoconfinement on the polymerization rate can be minimized through IFW. Chemorheology not only confirms the results obtained from DSC, but also shows that, in similar monomer conversions, the polymers obtained from the IFW system exhibit improved mechanical properties over the samples produced through the IFO process.