Volume 43 Issue 7, July 2011

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.

A series of silicon-containing aromatic bispropargyl ether resins, poly(dimethylsilylene-co-propynylene ether resorcinol) (polymer a), poly(dimethylsilylene-co-propynylene ether bisphenol A) (polymer b) and poly(dimethylsilylene-co-propynylene ether hexafluorobisphenol A) (polymer c), were synthesized. The obtained polymers displayed good heat resistance and processing properties. Degradation temperatures of the three cured polymers at 5% weight loss (T_d5) were above 400 °C. The flexural strength, flexural modulus and shear strength of composites of polymer c reached 408 MPa, 53.3 GPa and 24.8 MPa, respectively, which were higher than those of polymers a and b.

Polycarbonate/polystyrene (PC/PS) blend nanorods with various diameters were prepared by melt-wetting porous anodic aluminum oxide templates with partially miscible blend melts and the molecular composition distribution of PC/PS blends in various diameter nanopores was investigated by scanning electron microscopy, Fourier transform infrared and differential scanning calorimetry. Owing to the difference in viscosity between the two polymers during the capillary flow, gradient composition distribution of polymer blends was formed in nanopores.

The asymmetric diblock copolymer nanoparticles show a rich variety of novel structures, such as mixtures of distorted cylinders and spherical lamellae, due to the surface-field-induced effects from the nanoparticle surfaces.

A series of polyurethanes was synthesized in which hard segments were generated from the rigid 4,4-diphenylmethane diisocyanate (MDI) and the flexible 4,4-dibenzyl diisocyanate (DBDI), alone or as mixtures. Changes induced by varying the type and number of isocyanates were followed. Materials based on the single DBDI were observed to crystallize. Crystallinity was strongly reduced when DBDI was mixed with MDI. Improvement in elastomeric properties was obtained when both diisocyanates were included and reacted together in a random manner.

4,4′-[Oxybis(4,1-phenylenethio)]dianiline-based novel polyimides were synthesized from various dianhydrides. Most of the polymers were easily soluble in aprotic polar solvents and in tetrahydrofuran, and they exhibited remarkable film-forming ability. The obtained PIs showed high thermal stability and a large interval between glass transition temperature and the decomposition temperature values. Some of the polyimides exhibited relatively high refractive index of ∼1.9. The highest gas permeability was found for polyimide with hexafluoroisopropylidene units. This polymer also showed relatively good separation ability toward oxygen/nitrogen gas pair.

N,N,N’,N’-(tetrakis-2-pyridylmethyl)ethylenediamine–N-isopropylacrylamide (TPEN–NIPA) gels bearing polymerizable double bonds with different spacer length and branch structure are synthesized. The obtained poly(TPEN-NIPA) gels show thermoresponsive swelling/shrinking behaviors and are used for the extraction of cadmium(II) (Cd^II) ion. The polymer gels showed a temperature-dependent change of extraction performance between swelling and shrinking. Among these, TPEN gel-bearing C3 spacer with branched structure showed the best performance in Cd^II extraction.

The hydrophobic association of fluorocarbon-modified polyacrylamide aqueous solutions has been investigated on a mesoscopic level by considering the variation of root mean square (RMS) end-to-end distances using dissipative particle dynamics (DPD) simulation. Its hydrophobic association property is affected by the type of the hydrophobic group, salt, temperature and shear. The unit of stronger hydrophobic property within the chain makes the macromolecule have the greatest association in the solution.

This is the first report on dual synthesis of poly[(R)-3-hydroxybutyric acid] (PHB) and silk proteins by recombinant microorganisms for use in the fabrication of a biofunctional PHB-based material hybridized with functional proteins. The overall results illustrate the potential of this dual synthesis system as a versatile and useful platform method for preparation of biofunctional PHB-based materials, especially for biomedical applications.

Lignin-derived biomass-based polymers were synthesized by click polymerization using the copper (Cu)^I-catalyzed azide-alkyne cycloaddition. The in-situ prepared polymers displayed strong adhesion properties to metal surfaces. In particular, the specific adhesion to Cu with the maximum tensile strength of 3.7 MPa was achieved.

In our studies, we explored the viability of egg albumen (EA) and its blend poly (vinyl alcohol) (PVA) to produce nanofibers for biomedical applications. EA and PVA blends were prepared in various compositions. Electrospinning was used for fabrication of non-woven nanofibers. EA showed nanoparticles and microparticles instead of nanofibers at even higher contents. In contrast, a gradual increase in the addition of PVA content to 8% EA solution resulted in the transformation of nanoparticles from large agglomerates to very fine fibers (≈100 nm).

The prototype touch screen fabricated using the poly(3,4-ethylenedioxythiophene)/poly(4-styrenesulfonate)/polycarbonate (PEDOT/PSS/PC) film as a transparent electrode principally works as a touch pad for dragging (writing) a number ‘2’ by a finger.