The Structure Of Cationic Monomer On The Dispersion Of Nanosilica And The Properties Of PMMA Based Nanocomposites By Electrostatic Interaction

One of the fundamental issues upon the preparation of nanocomposites is to find a practical method for nanoparticle functionalization,stabilization,and transfer between media of different polarities.AmphipHiles appear to play a decisive role in avoiding aggregation of nanoparticles.The structure,composition and chemistry would affect the dispersion of nanoparticles and the compatibility with polymer matrix.In this thesis,polymer-based nanocomposites were prepared using SiO₂ as nanofillers,methyl methacrylate?MMA?as copolymerization monomer.Three kinds of assistant molecules were used to disperse SiO₂,and then copolymerized with MMA through suspension polymerization.The two assistant molecules,DTAB and MEC,contain positive charged group and polymerizable group.The third assistant molecules are cationic monomer,which have both positive charged group and polymerizable group.FTIR was used to investigate the interaction between polymer matrix and SiO₂.GPC and SEM were applied to investigate the effect of assistant molecules and SiO₂ on the molecule weight and microsphere morphology.TEM was used to characterize the dispersion of SiO₂ in polymer matrix.Meanwhile,the mechanical performance was also discussed.The result indicated that: the cationic monomer were synthesized successfully and compared with other molecules,the cationic monomer could improve the performance of nanocomposites more significantly.Assistant molecules could copolymerize with MMA efficiently.The addition of nanosilica and assistant molecules affect the roughness of microsphere and the molecular weight of PMMA.It is confirmed that there was strong electrostatic interaction between nanosilica and PMMA matrix in nanocomposite.The electrostatic interaction can improve the dispersion of nanosilica and interfacial compatibility between nanosilica and polymer matrix,and further improve the mechanical performance.Compared with pure PMMA,the P?MMA-co-C6MEDAB?/SiO₂ nanocomposite showed the best performance.The tensile and flexural strength of P?MMA-co-C6MEDAB?/SiO₂ nanocomposite increased by 22.9% and 60.0%,respectively.