Hydrogenation Of Neoprene Latex With Diimide And Template-Directed Synthesis Of Polystyrene In Microemulsion Systems

Hydrogenation of neoprene (CR) latex was carried out by the utilization of diimide with boric acid as a catalyst. Various hydrogenation conditions were studied and the hydrogenation degree can reach 48.1%. The most effective ratio of hydrogen peroxide/hydrazine hydrate was 0.8. The hydrogenation degree increased with increasing the temperature, the amount of boric acid and hydrazine hydrate. However, it decreased as prolonging the reaction time. The gel content was also investigated. Microstructure of hydrogenated neoprene (HCR) was characterized by IR and ¹HNMR.Microemulsion polymerization was carried out in a SDS-Al(NO+3)₃-H₂O system containing rodlike micelles. Polystyrene (PSt) obtained from this system was examined by GPC and IR analyses. To confirm the morphologies of the polymer products, several approaches were investigated for the particles purification and the subsequent samples preparation for TEM characterization, which indicated that only spherical nanoparticles were obtained from the diluted SDS-Al(NO₃)₃-H₂O diluting microemulsion region (Region 1) and the dialyzed SDS-Al(NO₃)₃-H₂O concentrated microemulsion region (Region 3). In addition, PSt products lost their particle morphologies after coagulated with ethanol and redispersed in H₂O. It can be concluded that polymerization of a hydrophobic monomer in the core of the micelles cannot capture the original rodlike micellar microstructure.PSt particles having nonspherical, sheet-like morphologies were synthesized in a heterogeneous system. Before reactants were introduced, a turbid system was primarily established at room temperature by adding KCl into a SDS-H₂O system to change the morphology of surfactant self-assembly aggregations and induce phase conversion. TEM, SEM and AFM studies indicated that the polymer particles were about 2 nm thick, whereas their plane size was irregular. There were apparent differences in thermal behaviors between the sheet-like PS (s-PSt) and the spherical PS obtained from the conventional emulsion system, viz. the former displayed an exothermic peak near 154℃during the first DSC scan, which disappeared in the subsequent scan and only one glass transition was exhibited. It appears from these results that the sheet-like polymer possesses special internal structures.