Syntheses and characterization of polymeric nanocomposites preperad by in-situ photopolymerization

Abstract

In this project, the objective was to synthesize a nanocomposite with a photoinitiator acting intercalent. With this motivation, in-situ syntheses of poly(methyl methacrylate) (PMMA) nanocomposites by photopolymerization using organophilic montmorillonite (MMT) as the layered clay, is reported. MMT clay was ion-exchanged with N-phenacyl, N,N-dimethylanilinium hexafluoro phosphate (PDA) which acts as both suitable intercalent and photoinitiator. The modified clay (MC) was then dispersed in methyl methacrylate (MMA) monomer in different loading degrees to carry out the in-situ photopolymerization. Two of the resulting nanocomposites obtained from the MC, the PMMA nanocomposite which was synthesized by using 3 % MC (PMMA-3%MC) and the PMMA nanocomposite which was synthesized by using 5 % MC (PMMA-5%MC) were found to result in a further increase in the d-spacings of the MMT layers at the value of 3.37 Å and 3.63 Å, respectively. On the other hand, for the PMMA nanocomposite which was synthesized by using 1 % MC (PMMA-1%MC), no d001 reflection was observed in the XRD patterns indicating complete exfoliated structure. It was also proved that PDA was organophilic enough to allow polymerization between clay layers. Intercalation ability of the photoinitiator and exfoliated nanocomposite structures were proved by both XRD and TEM. It was seen that even with 1 % degree of loading, the desired exfoliation was reached. Thermal properties were studied by using DSC and TGA. It was observed that the nanocomposite with exfoliated structure had the highest glass transition temperature (Tg) and thermal stability. Exfoliation-intercalation morphology of the resultant polymeric nanocomposites was also examined by using SEM and the results were discussed.