| It’s a key technology to improve the dispersion of nano-powder whose surface was modified by coupling agent in polymer nano-composites. Because the molecular weight and sequence structure of block copolymer are controllable, we can control the interfacial structure between nano-particles and polymer nano-composites more effectively. That’s to say, the dispersion of nano-powder and the macroscopic properties of polymer nano-composites are both improved greatly. In this thesis, two kinds of coupling agent (polymethyl methacrylate-b-polyvinyltriethoxy silane (PMMA-b-PVTES) and polyacrylonitrile-b-polyzinc methacrylate(PAN-b-PZDMA), which are amphiphilic block copolymers), were designed and synthetized by ATRP (atom transfer radical polymerization). And the influence law of the molecular weight and sequence structure of amphiphilic block copolymer(coupling agent) towards the dispersion of nano-powder was also studied.In chapter2, a "living" macromolecular initiator PMMA-Br(PDI≤1.21) and sevral kinds of block copolymers (coupling agents):PMMA71-b-PVTES5(Mn=8300, PDI=1.21), PMMA71-b-PVTES15(Mn=10222, PDI=1.35), PMMA71-b-PVTES24(Mn=11982, PDI=1.20) were successfully synthesized using ATRP and the polymer structures were characterized by1H-NMR、13C-NMR、29Si-NMR、FT-IR and GPC. The reaction characteristics of ATRP was conformed by MALDI-TOF MS for the end group of polymer agree with the initiator fragment well; The thermal properties of PMMA-Br and PMMA-b-PVTES were studied by TGA; Luckily, the block proportion gived by TGA correspond with GPC testing well too; The DSC curves of different proportion block copolymers tell us that, the glass transition temperature of PVTES decreased (PMMA71-b-PVTES11Tg=31℃, PMMA71-b-PVTES24, Tg=29℃), while the PMMA’s glass transition temperature rise with the PVTES block increased. Namely, the phase separation of block copolymers raised.The other "living" macromolecular initiator PAN-Br and sevral unique block copolymers (coupling agents):PAN138-b-PZDMA, PAN138-b-PZDMA5, PAN138-b-PZ DMAn, were synthesized successfully via ATRP and the polymer structures were studied by1H-NMR、FT-IR in chapter3; Compared with the TGA caves of PAN-b-PZDMA and PAN-Br. Firstly, We draws a conclusion that the block copolymer have higher thermal stability than the macromolecular initiator; We also can see that almost the same block proportion in viscosity average molecular weight gives by viscosity method and TGA analysis. The glass transition temperature of the block copolymer (PAN-b-PZDMA) rises along with the increased proportion of PZDMA.The large consumption in transition metal salts which can not be separated easily from the system was the mainly disadvantages in ATRP. In chapter4, several methods of copper ion removing method were compared and copper ion concentration was determined by inductively coupled plasma emission spectrometry (ICP). And a new way for copper ion removing was studied with sand-core filter, The results show that the copper removing method of sand-core filtration has many advantages of simple process, low cost (only one third volume solvent of dissolution and precipitation method for3times), high yield and low copper ion concentration (mass fraction of2×10-5) by comparison.In chapter5, the pretreatment condition of nano-Si3N4and the surface modified technology of nano-Si3N4using block copolymers (coupling agents):PMMA-b-PVTE S、PAN-b-PZDMA with different molecular weights and segments proportion was studied and improved; The results showed that, the amount of organic matter on the surface of nano-Si3N4is lowest, while the contents of-OH and-NH2are much higher after pretreatment at160℃for2hours, and the coupling agents can linked with nano-Si3N4through chemical bond easily. The properties of modified nano-Si3N4and raw nano-Si3N4were chareacterized by FT-IR, TGA, contant angle analysis et al. The reaction condition was optimized by the dispersion stabilization. With PMMA71-b-PVTES24and10%wt of nano-Si3N4in CHC13at75℃, The modified nano-Si3N4possessed the best dispersibility in ethyl acetate. TGA indicated that the using efficiency of PMMA71-b-PVTES24was53%, and chemical using efficiency reach37%. Transmission electron microscope (TEM) shows that the radius of nano-Si3N4modified by coupling agent (PMMA71-b-PVTES24) decreases obviously. Contact angle on the surface of modified nano-Si3N4changed from11.6°(with raw nano-Si3N4) to63.1°and the hydrophobicity was enhanced obviously;With PAN138-b-PZDMA5and9%wt of nano-Si3N4in ethanol at85℃, The modified nano-Si3N4possessed the best dispersibility in ethyl acetate. TGA indicated that the using efficiency of PAN138-b-PZDMA5was59%, and chemical using efficiency reach54%. Contact angle on the surface of modified nano-Si3N4changed from11.6°(with raw nano-Si3N4) to51.9°and the hydrophobicity was enhanced obviously too; We can see that the radius of nano-Si3N4modified by coupling agent (PAN138-b-PZDMA5) decreases in some degree by transmission electron microscope (TEM)... |
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