Research articles

Self-polycondensation of four different AB-type monomers including two novel monomers (monomers C and D) were carried out in the presence of potassium carbonate. High-molecular-weight poly(ether sulfone)s (M_w >110 000) were obtained from monomers C and D.

Poly(sodium styrenesulfonate)-block-poly(ethylene glycol)-block-poly(sodium styrenesulfonate) (PSS–PEG–PSS) and poly(methacrylic acid) (PMA) homopolymer were prepared via reversible addition-fragmentation chain transfer (RAFT) polymerization. When aqueous solutions of PSS–PEG–PSS and PMA were mixed below pH 5, water-soluble PSS–PEG–PSS/PMA complexes were formed due to hydrogen bonding interactions between the PEG block and the pendant carboxylic acids in PMA.

Bis-cyclopentadienyl titanium dichloride (Cp₂TiCl₂) is utilized as initiator for aqueous emulsion homopolymerization of 1,3-butadiene and isoprene and for copolymerization of the same diene monomers with styrene. The obtained homo- and copolymers are fully characterized by ¹³C nuclear magnetic resonance spectroscopy, thermal analysis and gel permeation chromatography.

Bulk free-radical polymerization of methyl methacrylate was studied by differential scanning calorimetry (DSC). Dependence of monomer conversion on time was calculated from the experimental DSC data. Proposed model, composed of two contributions to the monomer conversion was found to excellently describe experimental data. First contribution originates from polymerization according to classical theory of radical polymerization and the other from polymerization during the autoacceleration.

An original dispositive is used to study the effect of temperature on the conductivity of new materials based mainly on the conducting composites containing poly(aniline) and zeolite, these later exhibit reaction toward the carbon dioxide gas.

STEP Isodiametric design space based deposition of polymeric micro/nanofibers in hierarchical multi-layer assemblies with control on fiber diameter, spacing and orientation.

In the graph, the effect in the antibacterial activity of time and filler content in isotactic polypropylene (iPP)/ZnO composites is reported. Neat iPP has no bactericidal activity. For the composites, a decrease in the E. coli concentration is observed by increasing time. The effect is more evident for iPP/ZnO 95/5.

Crystallization kinetics and lamellar structure were revealed for miscible crystalline/crystalline blends of poly(vinylidene fluoride) (PVDF)/isotactic-poly(methyl methacrylate) (i-PMMA). i-PMMA was crystallized following the PVDF crystallization. In the crystallization of i-PMMA under the pre-existing PVDF crystalline lamellar structure, the induction period was considerably shortened compared to that of the neat i-PMMA, and the spacing of the PVDF crystalline lamellae was expanded.

Effect of α- or β-Copper phthalocyanine (CuPc) as a nucleating agent through crystallization of trans-1,4-polyisoprene (TPI) was evaluated. Observation by polarized optical microscopy showed that the low-melting crystal form is generated at the interface between TPI and either of α- or β-CuPc selectively when crystallized at 38 °C. In differential scanning calorimetry measurements, TPI composites containing α- or β-CuPc showed higher crystallization temperature than that of pure TPI during the cooling process from the melt.

Ni(0)-catalyzed coupling polymerizations of 3,6-di(4-chlorophenyl)-3,6-dihydrophthalic acid diethyl ester 1 were accompanied by isomerization of the 1,4-cyclohexadiene moiety into a 3,5-cyclohexadiene group, yielding a conjugated polymer. The structure of this conjugated polymer was the same as that of the conjugated polymer from 3,6-di(4-chlorophenyl)-1,2-dihydrophthalic acid diethyl ester 2. The conjugated polymer exhibited a λ max at 430 nm in the absorption spectrum, and could be applied as a photo-sensitizer of a solar cell. The incident monochromatic photon (450 nm)-to-current conversion efficiencies of photocurrent from an ITO/TiO₂ electrode modified with the conjugated polymer was 6.1% in the I₃^--3I^- electrolyte wet system.

PHBV/gelatin/laminarin (PHGL) biocomposite nanofibers composed of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), gelatin and laminarin were prepared by electrospinning process. The control of mixing ratio between gelatin and laminarin is the most important factor for the improvement of cytocompatibility of synthetic biodegradable polymer, PHBV. PHGL biocomposite nanofibrous scaffolds proved to be promising biomaterials suitable for tissue engineering.

The binding behavior of guests (dyes and DNA) into peptide nanocapsules formed via self-assembly of a 24-mer β-annulus peptide fragment obtained from the capsid protein of the tomato bushy stunt virus is reported. Binding of sodium 8-anilinonaphthalene-1-sulfonate and uranine into the peptide nanocapsules minimally affected the size of the nanocapsules, whereas binding of other anionic dyes resulted in the formation of precipitates. Complexation of the β-annulus peptide with M13 phage DNA formed a core-shell nanosphere in which the DNA was encapsulated in the peptide assembly.

A supramolecular polymer consisting of crystalline poly(ethylene adipate) end-functionalized with quadruple hydrogen-bonding ureidopyrimidinone via tolylene unit [PEA-Toly-UPy] were synthesized. When PEA-Toly-UPy was torn, the degree of crystallinity at the torn surfaces was more or less decreased by the energy dissipated by the tearing process.

In this paper, we have provided the first conclusive evidence that the Ni particle dispersed poly(methylmethacrylate) (PMMA) composites, which do not exhibit melting phenomenon, exhibit the positive temperature coefficient (PTC) effect when Ni content were 20 and 25vol.%. In particular, the composite with Ni content of 25vol.% exhibited PTC effect comparable to that of composites composed of crystalline polymer, and it demonstrated conductor/insulator transition. We assumed that these composites have few conductive paths, and so disconnection of conductive path occurred from slight volume expansion of PMMA by temperature rising.

Polydimethylsiloxane (PDMS) films were doped with 1% perfluoroether to lower the surface energy. Although the surface energy was lowered, the peel force did not decrease. It was found that peel force was linearly related to adhesive energy of films, and adhesive energy was inversely related to Young’s modulus. Films with low Young’s moduli evened out against surfaces easily and made good contact, which increased the adhesive forces, making the release hard. Comparatively, films with higher Young’s moduli had low peel force.

A series of novel photoactive high-performance polyamides bearing different functional group, such as CF₃, substituted imidazole and carbazole rings in their backbone, were prepared in direct polycondensation using ionic liquid media and triphenyl phosphate as an activating agent.

The particle scattering function (structure factor) P(q) of a two-dimensional flexible macromolecule (2D-FM), such as thin graphite oxide and graphene oxide, was calculated. The geometrical model used for shrinking the 2D-FM particle was the developable double corrugation surface (Miura folding) of a disk. This model described a three-dimensionally foldable and re-extendable shape and spontaneously exhibited self-avoiding condition inside a single particle. The obtained P(q) varied greatly according to the shape of the particle, which can change from a flat extended state to a three-dimensionally isotropic and dense shrunken state.

Photopolymerization of thin layers of a 75/25 (w/w) Bis-GMA/TEGDMA mixture exposed to a 465-nm monochromatic light radiation was first investigated. The final methacrylate conversion was measured by FTIR spectroscopy for different light intensities I₀. Then, the variation of the light flux intensity φ inside thick samples of the previous mixture containing mineral nanofillers (Al₂O₃ or ZrO₂) was calculated by means of a numerical model by taking into account the light scattering induced by the fillers. The obtained results permit the determination of the conversion profiles inside the loaded material and the maximal thickness that can be photopolymerized without consequent alteration of the polymerization yield and of the mechanical properties.