Preparation Of PMMA/CNTs Nanocomposites:Taking Advantage Of The Noncovalent Interactions Between CNTs And Auxiliary Comonomers To Enhance Interfacial Adhesion

Carbon nanotubes?CNTs? are one of the important fillers for polymer materials due to its excellent structure stability, favorable reinforcement effect, high thermal conductivity and electrical conductivity. However, there are strong intermolecular forces between individual CNTs. Therefore, it is extremely difficult to disperse CNTs in polymer matrix, which limits the application of carbon nanotubes. Often, surface modification of CNTs is recommended to improve the dispersion of CNTs in polymer matrix. However, the covalent modification of CNTs is always complex and time-consuming.In this thesis, polymer-based nanocomposites were prepared using commercial carboxylated CNTs: methyl methacrylate?MMA? was copolymerized with two kinds of auxiliary comonomers, 2-?methacryloyloxy? ethyltrimethyl ammonium chloride?MTC? and styrene?St?, respectively and collectively; simultaneously, carboxylated CNTs were incorporated into the polymer matrix. During the polymerization, carboxylated CNTs could interact with MTC and St through electrostatic interactions and ?-? stacking interactions, respectively.The results indicated that, each kind of auxiliary comonomers could be successfully synthesized with MMA, regardless of the presence of CNTs. In addition, it was confirmed that there is strong noncovalent interactions between the polymer matrix and CNTs in these nanocomposites with auxiliary comonomers loading. On the other hand, all the tested properties of nanocomposites were improved with the addition of auxiliary comonomers. With increasing auxiliary comonomers loading, the tensile properties of obtained nanocomposites showed a trend of firstly increasing to a maximum and then decreasing. It should be noted that, comparing with using MTC or St alone, the collective addition of both kinds of auxiliary comonomers could better assist the reinforcing ability of CNTs, thus giving rise to nanocomposites with better comprehensive performances. When the content of MTC and St was both 5 wt%, comparing with pure PMMA, the tensile strength, Young's modulus and strain at break of the nanocomposite were improved by 55.17%?48.88% and 31.19%, respectively; Meanwhile, the temperatures for 10% and 50% mass loss(T0.1 and T_0.5) were elevated by 39? and 40?, respectively.