Plasma polymerization and deposition of linear, cyclic and aromatic fluorocarbons on (100)-oriented single crystal silicon substrates J. Vac. Sci. Technol. A 20, 1955 (2002; 10.1116/1.1513640 X-ray photoelectron spectroscopy and scanning electron microscopy characterization of novel poly(monosubstituted) acetylenes containing doping species Plasma polymerization of pyrrole was carried out in the presence and absence of iodine, and the resulting films were characterized by optical and electrical means. Their infrared spectra were very similar to each other, suggesting that iodine was neither bonded in any manner to, nor strongly interacting with, the pyrrole polymer chains. Based on their infrared spectra, a chemical structure was proposed for the plasma-polymerized pyrrole ͑PPPy͒ film. An analysis of the electronic spectra gave band gap energies of 1.3 and 0.8 eV for the undoped and doped PPPy films, respectively. In line with this result, the current-voltage characteristics of the two types of polymer films revealed that the conductivity of the doped PPPy film was approximately two times greater than that of the undoped one. An investigation of the scanning electron micrographs led us to conclude that iodine had changed the surface morphology of the PPPy film, resulting in the small increase in conductivity. A detailed analysis of the conduction mechanism disclosed that the conduction mechanism in the undoped PPPy film is a Schottky-type mechanism.

Metallic and semiconducting single-wall carbon nanotubes (SWCNTs) were separated by selective adsorption and desorption using agarose gel beads and SWCNTs/sodium dodecyl sulfate dispersion. Comparison to the batch method, the purities of metallic and semiconducting SWCNTs obtained by a column method were improved to 90 and 95%, respectively. When linear-gradient elution was applied to the column method, semiconducting SWCNTs and presumed mixed bundles could be separated into early-and late-eluted fractions, respectively. In the semiconducting fractions, chirality separation was also detected.

We investigated the influence of the mixed n-alkanethiolate self-assembled monolayer (SAM) formed on gold nanoparticles (AuNPs: 50.0 ± 3.2 nm in diameter) on their assembly into colloidal films. Dodecanethiol and octadecanethiol were selected as the short- and long-chain alkanethiols, respectively. The mixed SAMs were formed by immersing AuNPs in a mixed alkanethiol solution at different molar ratios. Au colloidal films were fabricated on indium tin oxide substrates by our previously reported hybrid method. The composition of the two alkanethiolates in the SAM was deduced from the intensity ratio of two Raman bands at 1080 and 1105 cm(-1). The surface coverage of the colloidal films increased by forming equimolar or dodecanethiolate-dominant mixed SAMs on AuNPs instead of a pure dodecanethiolate or octadecanethiolate SAM. The highest coverage exceeded 80%. This improvement is attributed to the high dispersion stability of AuNPs covered with equimolar or dodecanethiolate-dominant mixed SAMs.

Summary: The title polymers, in which both the stem and the graft are biodegradable, have been synthesized for the first time in a one‐pot, lipase‐catalyzed, graft‐polymerization reaction (in bulk, at 70 °C) of β‐butyrolactone (β‐BL) and ε‐caprolactone (ε‐CL) onto chitin and chitosan. The reactivity order of the lactones was found to be ε‐CL > β‐BL ≫ γ‐BL (no reaction). All the graft polymers prepared are insoluble in common organic solvents.Synthesis of chitin‐ or chitosan‐graft‐aliphatic polyesters.imageSynthesis of chitin‐ or chitosan‐graft‐aliphatic polyesters.

Abstract:The ring-opening polymerization of L,L-lactide by using immobilized lipase Candida Antarctica (Novozym 435) as a catalyst at a temperature of 100 o C in bulk was conducted. This process was found to yield the corresponding poly(L,L-lactide) (PLLA) with weight-average of molecular weights of about 2,440 and a polydispersity index of 2.63. It was observed that the increase of the reaction time and amount of enzyme catalyst resulted in the polylactides with higher molecular weights.