Study Of Photo-Grafting/Cross-Linking On Latex Particle Surface And Preparation Of Functional Materials

Nano-materials are becoming the crucial foundation of the next generations of information, energy and bio-medicinal techniques for their prominent properties. Nowadays, the studies focusing on the functional nano-materials especially on the surface of nano-materials have been of great interest.In this dissertation, nano-particles of rubber latex with initiating functional groups on surface have been prepared via surface photo-grafting/cross-linking strategy. By employing these functional nano-particles of rubber latex, core-shell composite particles, supper water absorbent resin and supper oil absorbent resin have been successfully prepared. The main contents of the present work can be summarized as follows: 1. Under UV irradiation instead of y-rays irradiation, fully vulcanized rubber latex was preparated using intermittent or continuous strategy. Compared with y-rays irradiation technique, UV irradiation technique produce a relatevly lower gel content of vulcanized rubber, but still exceeding90%. Latex could be dried easily by spray to achieve powdery rubber without adding any separate agents. The advantages of fast, convenient, less investment and energy-saving make the UV irradiation vulcanization method competitive in industry.2. Through the coupling of semi-pinacol groups generated by BP hydrogen abstracting on the surface of rubber latex, a latex macroinitiator with immobilized dormant groups was produced. FTIR and UV spectrum anlysis, NMR and XPS measurements confirmed the combination of semi-pinacol groups on the surface of rubber latex. The mounts of semi-pinacol groups fixed on particle surface could be increased via the introduction of trimethylpropane triacrylate (TMPTA) during UV irradiation.3. Using NBR particles with immobilized dormant groups as initiator, the grafting polymerization of styrene (St), acrylamide (AM) and N-vinyl pyrrolidone on NBR surface was studied. Multi-layer composite core-shell particle could be obtained after grafting polymerization. In the process of polymerization, the direction of grafted chains grew was driven by solubility of grafted chains in water:oily PSt grafted chain would grow towards the center of particles while hydrophilic PAM and PVP would grow towards water mediate. Composite core-shell particle was made up of NBR as core, NBR-co-PSt as inner layre and PAM or PVP as outer layer. The grafting efficiency is quite high, i.e. approx.90%, and it does not change with reaction time and rubber/monomer ratio.4. Applying spheres with immobilized dormant groups as initiator, supper water absorbency resin with particle cluster was successfully prepared using acrylamide (AM)/acrylic acid (AA) as monomers and N,N’-methylene-bisacrylamide (MBA) as cross-linker, and according the procedure of constructing cluster network at first via reaction of particle and MBA, and then grafting polymerization of hydrophilic monomer induced with the remained dormant group on particle surface.The prepared resin is constructed with pre-cross-linked particle cluster and the PAM/PAA hair chains on particle surface. Absorption cells are made up of particle cluster and grafted chains. The hydrogel network consists of a few of chemical cross-link and a plenty of chain-chain and chain-network entanglements. With the unique hydrogel structure, super high absorbency can be obtained by changing the AA content. Hydrogels can absorb exceeding10000times in deionized water,500times in tap water and250times in0.9wt%NaCl solution. 5. Using particle with surface dormant group as initiator, high oil absorption resin with particle cluster was synthesized with stearic acrylate (SA), methyl methacrylate (MMA) and butyl acrylate (n-BA) as monomers, divinylbenzene (DVB) as cross-linker. Similarly, the resin was prepared with method of constructing cluster network first and then induced surface grafting polymerization on particle. Grafted chains were composed of PSA/PMMA or PSA/PBA copolymer. Oil absorbency increased with SA content in grafted chains. The absorbency can reach at80times in toluene.