Reviews & Analysis

Polyolefins (polypropylene (PP), polyethylene and so on) and polyolefin rubbers (ethylene propylene diene monomer, ethylene propylene elastomer and so on) are the most widely used polymers. Therefore, a development of a polyolefin and polyolefin rubber–clay nanocomposite has been desired for a long time. As these polyolefin polymers do not include any polar groups in its backbone, it was thought that the homogeneous dispersion of the silicate layers would not be realized. But we have successfully developed these polymer–clay nanocomposites by using various methods.

The footprints of a macromolecular synthetic chemist were left on the sands of time. Novel anionic addition polymerization of fluorinated vinyl monomers, which generally show poor homopolymerization reactivity, has been developed. Anionic polyaddition has been achieved by the double Michael addition of bis(2-trifluoromethylacrylate)s to active methylene compounds. Radical addition of fluorinated vinyl monomers with many organic compounds possessing carbon–hydrogen bonds has been accomplished and amplified to the polyaddition reaction to incorporate fluorinated vinyl monomers into polymer main chains. The facile carbon–carbon bond formation reactions have been accomplished by the aid of fluorine substituents.

This article reviews the living homopolymerization and copolymerization of propene, 1-alkene and norbornene with ansa-dimethysilylene(fluorenyl) (amido)dimethyltitanium and its derivatives, 1–4, correlating with the effects of cocatalysts, solvents and the substituent of the fluorenyl ligand on the catalytic features, such as livingness, propagation rate, syndiospecificity and copolymerization ability. The synthesis of novel olefin block copolymers and their catalytic synthesis are also introduced by the use of the living system.

The movement toward a recycling-based society through the essential development of recyclable materials alongside technologies for controlling recycling, for example, upgrade recycling of commodity plastics, selective transformation of engineering plastics, selective depolymerization of various polymers in supercritical fluids, crosslinking-decrosslinking control using reversible reactions and developments in biomass-based recyclable polymers is reviewed.

New types of polymer hydrogels (nanocomposite gels, NC gels) and soft polymer nanocomposites (M-NCs) with novel organic/inorganic network structures were synthesized using disk-like inorganic clay nanoparticles as multifunctional crosslinkers to form new network systems. Both NC gels and M-NCs have extraordinary optical and mechanical properties, such as ultrahigh reversible extensibility, as well as a number of new characteristics relating to polymer/clay morphology, stimulus-sensitivity, biocompatibility, surface properties, micropatterning and so on. The serious disadvantages (intractability, mechanical fragility, optical turbidity, poor processing ability, low stimulus sensitivity) associated with the conventional, chemically crosslinked polymeric materials were overcome in NC gels and M-NCs.