Modification Of GO Based On Click Reaction And Its Composite With Poly(Vinyl Alcohol)

The development of new carbon materials has been a hot research topic in recent years.As an important member of the carbon materials,graphite oxide(GO)has a unique quasi-2D layer structure and excellent mechanical properties.Moreover,GO contains the rich superficial functional group and its surface modification shows great research and application value in composite materials.Chemical modification of GO based on click reaction was studied in this paper.On one hand,by adding functionalized GO into poly(vinyl alcohol)(PVA)matrix and using a wet-spinning method,PVA/p-mGO composite fibers with enhanced mechanical properties can be prepared.On the other hand,by a solvent casting method,composite films with better shape memory properties can be prepared,which also show good reinforcing effect.The main research details and conclusions are as follows:(1)We present a novel approach to the functionalization of GO based on click reaction.The modified GO(mGO)was bonded with PVA to get PVA grafted mGO(p-mGO),and structure and dispersion of the functionalized GO were characterized.~1HNMR,FTIR,UV-vis and Raman spectra have proved that the chemical bonding between PVA and GO existed.And microstructure of p-mGO was characterized by AFM and TEM.Because more PVA chains are bonded on the surface of graphene sheets,p-mGO shows greatly improved dispersibility in water and other polar solvents,and even in PVA matrix.Moreover,the PVA grafted GO(p-GO)without click modification which was directly bonded with PVA was also prepared as a contrast.And the results indicated that the improvement on dispersion of p-GO in which the PVA chains only distributes at the edge,is not so good as that of p-mGO.(2)P-mGO with better dispersion was added into PVA matrix as filler to prepare PVA/p-mGO composite fiber using a wet-spinning method.And the p-GO was also prepared treated with the same spinning process to be contrast.The surface morphology,crystalline and orientation properties and mechanical properties of the composite fiber were studied.The results show that with the same loading of graphene sheets,p-m GO exhibited higher enhancement on mechanical properties of composite fibers than p-GO,which is attributed to better dispersion and stronger interfacial interaction in PVA matrix.(3)Based on the unique structure with PVA chains on the surface of the sheets,p-mGO was selected as filler for PVA to make shape-memory composite films.The shape memory and mechanical properties of shape memory PVA were studied.Because of enhanced interfacial interaction between GO and PVA matrix,crosslinking points increased and the proportion of hard segment domains increases and the final recovery rate of PVA/p-mGO composite films can be improved,up to 98.3%.However,the presence of GO sheets hinders the motion of soft segment in PVA matrix,which can decrease the recovery speed of composites.The result of tensile test of the memory polymer indicated that the p-mGO shows more greatly improved tensile strength and modulus than p-GO.