Original Article

Novel combined liquid crystalline (LC) polymers based on ethyl cellulose (EC) were synthesized by N,N′-dicylcohexylcarbodiimide coupling, and the effect of flexible spacer length on the mesophase structure was investigated. The results showed that the mesophase structures of polymers consisted of a large-scale ordered lamellar structure constructed by EC backbone and a relatively small-scale ordered structure formed by azobenzene side chains. All the polymers form the similar lamellar structure at large scale; however, the small-scale ordered structure becomes disordered relatively, that is, from crystal (m=2) to smectic B (m=4) to smectic A (m=6) at lower temperature.

Maleic anhydride grafted polypropylene (PP-g-MA) with different grafting contents and approximately the same molecular weight was prepared. The grafting content of PP-g-MA in the range of 0.2–1.4 wt% shows no appreciable influence on the dispersion of organoclay, whereas the loading of PP-g-MA can effectively influence the intercalation and delamination of clay. The intercalation and exfoliation mechanism of prepared PP-g-MA is discussed and compared with that of PP-g-MA oligomer.

The effective volume V_E excluded to a Kratky–Porod (KP) worm-like ring by the presence of another, resulting only from a topological interaction, was evaluated by Monte Carlo simulations. The quantity λV_E/L² proportional to the second virial coefficient A₂ was shown to be a function only of λL with λ⁻¹ the stiffness parameter of the KP ring and L its total contour length.

An antibacterial quaternary ammonium acrylic monomer 1 was synthesized by quaternization of 2-dimethylamino ethyl methacrylate with dimethyl sulfate. This synthetic route was able to obtain the quaternary ammonium monomer 1 of high yield and low cost. The corresponding homopolymers were then synthesized by free radical polymerization using potassium persulfate as the initiator and H₂O as the solvent. Interestingly, it was found that 2 had significantly higher antibacterial activity than 1, although 1 exhibited moderate antibacterial activity.

Condensation reactions between tetraethylorthosilicate and cyclohexanediol derivatives resulted in crosslinked poly(orthosilicate)s. These polymers have good and fast swelling abilities in organic solvent and they also release the absorbed solvent very easily.

Aniline sulfide resin (ASR) is synthesized by the reaction of aniline and sulfide dichloride. Crosslinked ASR (ASC) has been prepared in the presence of ammonium peroxydisulfate and aniline in aqueous solution as oxidant and monomer, respectively. By changing the ratio of ASR to aniline during the polymerization reaction, it is possible to control the number of crosslinked sites, electrical conductivity, molecular weight and solubility. Electropolymerization was carried out by coating ASR on the surface of glassy carbon disk electrode, and then grown on a graft copolymer ASC in the presence of fresh aniline and acidic solution. Electrical conductivity of ASC has been studied by four-point probe method and produced 8.5 × 10⁻³ S cm^–1 conductivity for it.

Cast technique was used to prepare new nanocomposite thin films of pure and GdCl₃- or HoCl₃-doped polyvinylpyrrolidone (PVP) with different dopant concentrations. During magnetic measurements, using a vibrating sample magnetometer, carried out at room temperature and applied magnetic fields up to 10 kO_e, thin films of the system PVP-HoCl₃ showed slightly better magnetic properties than PVP-GdCl₃. A comparative infrared and ultraviolet-visible spectral analysis of the parent components and their nanocomposites provided an indication to the effective role of dopant nature and concentration in morphological and microstructural changes occurring in the PVP matrix.

Novel fluorescent polyimides (PIs) were prepared from a new diamine, 4-(4-(4-amino-2-(4,5-diphenyl-1Hi-midazol-2-yl)phenoxy)phenoxy)-3-(4,5-diphenyl-1H-imidazol-2-yl)benzenamine(DA), and three tetracarboxylic dianhydrides. The PIs are amorphous and soluble in polar aprotic solvents and demonstrate a film-forming capability; their inherent viscosities ranged from 43 to 82 ml g⁻¹. The PIs show emission in dilute (0.2 g per 100 ml) N,N-dimethyl acetamide solution with photoluminescence (PL) quantum yields in the range of 11–25%. The chemiluminescence (CL) activity of PIs in the presence of peroxyoxalate was also investigated.

Asymmetric anionic homopolymerizations of N-4′-benzo 15-crown-5 maleimide (B15C5MI) were carried out with a chiral anionic initiator consisting of organometal and chiral ligand to obtain optically active polymers. Chiroptical properties and structures of the polymers obtained were analyzed by CD, UV, NMR and gel permeation chromatography measurements. The additional effects of (R)-cyclohexylethylamine ((R)-Cyc) to the obtained poly(B15C5MI) were investigated.

Sulfonated free-standing films were prepared by sulfonation of the free-standing films of 3-mercaptopropyl(trimethoxy)silane (MTMS)/1,2-bis(triethoxysilyl)ethane (BTESE) copolymers. The sulfonyl group content was 1.23 mmol g⁻¹ when the composition of MTMS/BTESE was 1:2, which sulfonyl group content at 150 °C was 1.20 mmol g⁻¹.

The WAXD image and the fiber temperature were measured as a function of elapsed time t calculated on the basis of the distance (D) from the neck-drawing point divided by the fiber running speed. The distance D was controlled by shifting the neck-drawing point with the traveling mirror unit.

Vaterite particles were obtained by a ‘carbonate controlled-addition method’ by G0.5 poly(amidoamine) (PAMAM) dendrimer with carboxylate groups at the external surface. The average particle sizes of the spheres decreased from 2.2±0.2 to 0.61±0.24 μm and the stability of the spheres increased with an increase in the incubation time of the G0.5–CaCl₂ solution from 3 min to 24 h. The interaction and reaction kinetics of the dendrimer–Ca²⁺ complex have an important role in the mineralization of CaCO₃.

When poly(methyl methacrylate) (PMMA) film doped with (Z)-N-acetyl-α-dehydroarylalanine naphthyl esters ((Z)-1) was irradiated with unfiltered light from a high-pressure mercury lamp, (Z)-1 underwent heterolytic cleavage of the ester bond preferentially in PMMA film to give arylmethylene-substituted oxazolone and naphthol derivatives as major products. This photochemical transformation enhanced the refractive index of this polymer film in the range of 0.001–0.020, depending on the structure of the aryl substituents.

Optical properties of thin films based on thermostable poly(oxadiazole-naphthylimide)s were investigated. The main absorption maxima of the films were centered at about 301–308 nm, their intensity and positions remaining almost unchanged up to 250 °C. The Kramers–Kronig analysis applied to the reflectance spectra yielded the extinction coefficient and refractive index values. The energy gaps obtained from the edge of the absorption coefficient, based on transmission and reflectivity measurements, were found in the range of 2.77–3.04 eV. In photoluminescence spectra, three maxima in the UV and blue spectral range were detected.

Model reactions of calix[4]resorcinarene (CRA), p-tert-butylcalix[n]arene (BCA[n], n=4, 6, 8) and their esterified derivatives with glycidyl phenyl ether (GPE) were examined using tetraphenylphosphonium chloride (TPPC) as the catalyst in chlorobenzene at 120 °C for 6 h. It was found that the degree of introduction of GPE (D.I.) to CRA series was higher than 95%, whereas for BCA[n] (n=4, 6, 8) series, D.I.s were lower than 81%. Therefore, CRA and its derivatives are good potential curing agents for preparing cured epoxy resins with excellent thermal properties.

We succeeded in elongational crystallization of isotactic polypropylene (iPP) by compressing the supercooled melt. When the elongational strain rate ( ) surpassed a critical value ( *=2×10² s⁻¹), crystallization behavior and structure discontinuously changed. The induction time decreased by 10⁻⁶ times (Figure), the crystal size decreased by 10⁻³ times and morphology changed from spherulites to ‘nano-oriented crystals (NOCs)’. It is concluded that large induced the ‘oriented melt’ and NOCs. The NOCs showed high crystallinity and ultra-high performances, such as high tensile stress (210 MPa).

The structure of polyethylene/polydimethylsiloxane polymer composites prepared by using supercritical carbon dioxide could be controlled in the depth direction. It depends on the control of the mass gain, namely, the polymerization time.

The high-resolution solid-state NMR technique was applied as a bulk analysis method to provide an indication of nano-clay dispersion in starch–clay nanocomposites. The effects of having polyvinyl alcohol as additives and aging up to 105 days were also investigated.

The defects and heterogeneous system of polyaniline (PANI) doped in benzene sulfonic acid (BSA) with a crystalline region dispersed in an amorphous low-conducting region as shown in the scanning electron microscopy micrograph reveal the current–voltage characteristic, which shows a nonohmic variation. It increases in current with applied voltage owing to the conduction mechanisms of PANI due to the formation of polarons and bipolarons. As the applied voltage increases, the formation of polarons and bipolarons increases rapidly, contributing to higher values of current through sample. This characteristic affects the dielectric behaviors of the elaborate composites.

By introducing different notch depths on the width direction of dumbbell samples of PET, the skin-core structure, notch depth and fracture modes of PET are correlated with the crack-tip temperature. The gray and infrared images of samples show the changes in fracture modes and crack-tip temperatures as notches become core deep. Maximum crack-tip temperature occurred because of crazing in a mixed mode of fracture at 1- to 1.5-mm-deep notches (d–f), considered the terminal end of the skin and interface between the skin and core regions.