Modelling Silica in Aggregates of Block Copolymers*

There is developing interest in the use of Periodic Porous Materials (PPMs) synthesized from silicic acid and amphiphilic block copolymers in drug delivery and catalysis. Existing studies of the formation of PPMs have not drawn a clear conclusion as to the formation mechanism. In the prior studies two formation mechanisms were suggested; Liquid Crystal Template (LCT), where silicic acid plays no active role in the formation, and Co-operative Mechanism, where silicic acid plays a role in the formation.
In this study, we have investigated how the presence of silicic acid affects the self-assembly of these block copolymers by employing molecular dynamics simulations of coarse-grained (CG) models of Polyethyleneoxide-b-polybutylmethacrylate (PEO-b-PBMA) with silicates in water and tetrahydrofuran. An existing CG silicic acid model [1] could not reproduce the water-silicic acid interaction observed experimentally. We have developed a more effective silicic acid CG model by comparing the solvation free energy of silicic acid in solvents with the values obtained from DFT calculations, which will allow for the determination of the correct formation method of PPMs.


Reference: 1. Pérez-Sánchez et al., Langmuir, 29, 2387 (2013)