Volume 42 Issue 3, March 2010

10,12,14,16,18,20-Triacontahexayne-1,30-diol and its diphenylurethane and diphenylester were synthesized, and their solid-state polymerization behaviors were investigated. The regular two-step solid-state polymerization was confirmed for the diphenylurethane derivative.

A crown ether–ammonium salt-type rotaxane monomer was synthesized in a high yield using dibenzo-24-crown-8-ether and sec-ammonium salt having a hydroxy terminal by means of an end-capping reaction with an ethynyl benzoic acid. Its N-acetylated derivative was also synthesized as a neutral monomer. Novel side chain-type polyrotaxanes, that is, ammonium-type and neutral polyphenylacetylenes tethering rotaxane moieties in side chains with high molecular weights were obtained in high yields by polymerizations with an Rh catalyst. N-acetylation of the rotaxane moieties of the ammonium salt-type polymer afforded a red-colored neutral polymer showing red-shifted UV-vis absorption due to the conjugated main chain, according to the change in distance between the wheel component and the polyacetylene main chain.

A series of new 1,2,3-triazole-containing polytriazoleimides was synthesized by the copper-catalyzed click polymerization of azide–alkyne cycloaddition. The click polymerization of imide-containing dialkynes with the diazide could produce new polymers with imide and triazole units in the main chain.The polytiazoleimides obtained, with inherent viscosities of 0.39–0.58 dl g⁻¹, had good solubility in polar solvents and could be cast into transparent, tough and flexible films. These novel polytriazoleimide films exhibited good thermal stability and mechanical properties

Delaminated PS/magadiite and PPE-PS/magadiite nanocomposites were successfully prepared by a combination of surface-initiated polymerization and a melt-blending process. For a series of PS/magadiite composites, their PHRR values decreased with improvements in magadiite dispersion. Exfoliated PS/magadiite nanocomposites exhibited the lowest PHRR, forming seamless and strong solid residues.

Addition effects of a series of N-alkyl-substituted methylimidazolium salts ([CnMim][X]) on the mesophase structure and LCST-type phase-separation behavior, and the ensuing optical properties of concentrated hydroxypropyl cellulose (HPC) aqueous solutions, were investigated by spectrophotometry and complementary X-ray diffractometry. Salted HPC solutions exhibited distinct shifts in both the cholesteric pitch and the cloud point, relative to the nonionic reference. Discussion of the observations took into consideration the differences in the N-alkyl structure and amphiphilic nature between the imidazolium varieties, as well as the difference in a socalled chaotropic strength between the anions used.

The variations in the free volume and the thickness of the active polyamide layers of the composite membranes were obtained by positron annihilation spectroscopy (PAS) experiments, in which a variable monoenergy slow-positron beam was used. The data on Doppler broadening Sparameters vs annihilation radiation energy spectra showed that the active MPDASA-TMC layer of the composite membrane had a lower free volume and was thinner than the active MPDA-TMC layer. This result corresponded well with that from the pervaporation performance of TFC polyamide membranes.

Sulfur-containing acrylic monomers were developed for high refractive index. The index of polymer films increased with the number of sulfur atoms in the monomer structure. Trisulfur-acrylic polymer provided refractive indices of more than 1.72 at visible light. Dipolar phenyl structure significantly increased the refractive index of acrylic polymers. Wavelength dispersion of the refractive index was investigated with Abbe's number of ca. 30 for all polymer films, except for the dipolar polymer viewing Abbe's number of ∼41.

Water-soluble pachyman (WSP) was prepared by enzymic hydrolysis of pachyman extracted from Poria cocos sclerotium. Two WSP fractions, WSP-1 and WSP-2, both of which were β-(1→ 3)-D-dextran, were separated by SephadexG-100 from WSP. The figure displays the Infrared analysis of pachyman, water-soluble pachyman, WSP-1 and WSP-2.

A new kind of modified bismaleimide resins made from 4,4'-bismaleimidodiphenylmethane, hydrogen silsesquioxane, dipropargyl ethers of bisphenol A, dipropargyl ethers of hexafluorobisphenol A, dipropargyl ethers of 4,4'-dihydroxydiphenyl ether and dipropargyl ethers of resorcinol, with good heat resistance and processing properties for advanced composites, was developed. The cured resins showed a high glass transition temperature (Tg) (>330 °C) and a high thermal decomposition temperature (Td5) (>400 °C).

The synthesis of well-defined poly(4-(2-(tert-butyldimethylsiloxy)ethyl)-styrene-b-isobutylene-b-4-(2-(tert-butyldimethylsiloxy)ethyl)styrene)(PTBDMES-b-PIB-b-PTBDMES) triblock copolymers was accomplished by cationic sequential block copolymerization of isobutylene (IB) and 4-(2-(tert-butyldimethylsiloxy)ethyl)styrene (TBDMES) using the capping-tuning technique in a one-pot procedure in methylcyclohexane/CH₃Cl at −80 °C. Deprotection of the precursor triblock copolymer with tetrabutylammonium fluoride yielded poly(4-(2-hydroxyethyl)styrene-b-isobutylene-b-4-(2-hydroxyethyl)styrene) (PHOES-b-PIB-b-PHOES), with pendant hydroxyl groups along the hydrophilic backbone chains. FT-IR, NMR confirmed that hydrolysis was complete.

The effects of the degree of hydrolysis (DH) of poly(vinyl alcohol) (PVA) on electrospinning and water resistance of electrospun PVA/poly(acrylic acid) (PAA) composite fibers were explored. At a constant concentration of PVA solution (∼8wt%), the average diameter of electrospun PVA fibers increased with increasing DH. The water resistance of heat-treated PVA/ PAA composite fibers was dramatically enhanced, and was also affected by PAA weight fractions (φPAA) in PVA/PAA blend solutions.