The Preparation And Application Study Of Isocyanate-functionalized Polystyrene

Functional group functionalized polymer refers to the introduction of reactive functionalgroup to the polymer main chain and side branches, and with reversible or irreversible physicalor chemical activity. Functionalized polymer can significantly improve the performance ofpolymer materials or have some new functions. So far, functionalized polymer materials havebeen an important way to achieve high-performance materials.Polystyrene as a common general plastic, brittleness, and poor heat resistance limit itsapplication. To overcome the limitations of polystyrene, we can modify polystyrene withfunctional group, prepare the composites with inorganic nanoparticles and proceed activepost-reaction of the functional group with the usage of highly reactive active of the functionalgroup.Styrene and polar monomer3-isopropenyl-α, α’-dimethylbenzene isocyanate (TMI)containing isocyanate functional group (-NCO) were used to prepare the copolymer of styreneand TMI, denoted as P(St-co-TMI) by solution radical polymerization in the high pressurereactor, so achieved the modification of styrene with the functional group. Fourier transforminfrared spectroscopy (FT-IR) and nuclear magnetic resonance spectroscopy (1H-NMR) resultsshowed that the isocyanate groups were successfully introduced to the main chain of PS, and thecopolymerization composition of TMI increased with the increase of TMI content.Considering the high reactivity of the isocyanate, we prepared the composites offunctionalized polystyrene P(St-co-TMI) with inorganic silica particles. Firstly, P(St-co-TMI)with the presence of silane coupling agent3-aminopropyl triethoxysilane (APTES) were used toprepare the hybrid precursor, then prepared chemical covalent bonded P(St-co-TMI)/SiO2composite materials in situ sol-gel method by adding tetraethoxysilane (TEOS). The resultsshowed that the isocyanate groups have reacted completely, and the inorganic SiO2particlesexhibited good distribution in the polystyrene matrix with the presence of the coupling agent.Meanwhile, the glass transition temperature Tgand thermal stability of the resulting composite material increased with the increase APTES content, the viscoelastic behavior of compositematerials behaved obviously in the strong covalent bond condition.The presence of isocyanate group in the Polyurethane material may decrease its thermalproperties, but the cyclotrimerization reaction of isocyanate can increase the thermal stability.Using the cyclotrimerization reaction of isocyanate in P(St-co-TMI) simulated polyurethanecyclotrimerization reaction to improve thermal stability. We prepared isocyanurate highperformance materials by adding monoisocyanates TMI, p-tolyl isocyanate (TI) and methylenediphenyl4,4’-diisocyanate (MDI) to the cyclotrimerization system with using P(St-co-TMI) asthe main substrate component. The results showed that the absorption peak of isocyanateweakened or even disappeared, meanwhile the thermal analysis test indicated the thermalinstability peak belonging to TMI disappeared, the thermal stability is improved and exhibitedmore obvious with the increase of adding isocyanate monomer content.