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Silicone modified polyurethane (PUSX) has attracted interest as a useful material by various properties, which are combined with silicone and polyurethane. In this paper, we tried to optimize the electrospinning process of silicone modified polyurethane (PUSX) nanofibers on a lab scale device and a multinozzle pilot scale set-up to investigate the potential and limitations of preparing PUSX nanofibrous sheets using different equipment. The morphology and diameter of the obtained fibers were studied via scanning electron microscopy (SEM). Attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) was also carried out to analyze the chemical structure of PUSX nanofibers. As a result, we successfully figured out the optimal parameters of PUSX electrospinning process and demonstrated the great potential of the process for mass production of PUSX nanofibrous sheets from solutions.

In the crosslinking reaction of primary polymers, the rate constant R(i, j) can be described by R(i, j) = iαjα (α ≤ 1). If α ≤ 1 2 or 1 2 , products are microgels or macrogels, respectively. Clusters of μm-order sizes were prepared by the crosslinking of St(styrene)-HEMA (hydroxyethylmethacrylate) microgels (d = 260 nm) with glutaraldehyde (crosslinking agent) and HCl (catalyst), as a model of gels. These clusters were observed under the microscope. The microscopic negatives of the clusters were illuminated with light and the fractal dimension D of the clusters was determined by the transmittance of the light. The cluster size ( 0.9 3.0 μm ) did not affect the value of D (2.65–2.82). The concentration (0.4–2.0 wt%) of HCl also did not affect D of the clusters. When the microgels were crosslinked in the medium containing NaCl (2 wt%), D decreased (2.11–2.67). The ‘rapid aggregation’ of the gels occurred because of large ionic strength.

The crosslinking reaction of primary polymers under the influence of potentials was studied by computer simulation. Under the predominant action of repulsive potential, macrogelation did not appear and the products remained as a sol (microgel). With increasing repulsive potential, the particle size descended and the final size distribution became narrow (Pw/Pn = 1·06; Pw, weight average degree of polymerization; Pn, number average degree of polymerization). By the simulation according to a diffusion limited aggregation model with distant repulsive potential and short distant weak attractive potential, round and dense particles were obtained. In the crosslinking reaction of partially quaternized poly (4-vinylpyridine) (q-P4VP), the size of the particles declined and the size distribution became narrow with the quaternization degree of q-P4VP. This result agrees with that of the simulation.

Gelling time τg of the crosslinking in which the rate constants of inter cluster reactions between i-mer and j-mer is proportional to (ij)α(1/2

Lithium-metallated styrene–p-benzylstyrene copolymer was reacted with chlorine-terminated polystyrene as a crosslinker polymer in tetrahydrofuran (THF) at 25°C. The rate constant was estimated from the changes in the concentration of metallated polymer by using photometrical measurements. The various reaction conditions were chosen and it became clear that the rate constants of grafting (k1) and intramolecular crosslinkings (k2intra) were gotten separately at the first stage. As a result, k2intra showed larger values than k1 and decreased with increasing degree of polymerization of crosslinker polymers.

RuH2(PPh3)4 and other hydridoruthenium complexes catalyze selective conversion of aldehydes into esters in high yields. The method is applicable to most aliphatic aldehydes as well as to aromatic aldehydes. The purity of aldehydes is critical for achieving high conversions, since the presence of carboxylic acid completely inhibits the reaction and alcohol and triphenylphosphine reduce the yields of esters. RuH2(PPh3)4 is converted into Ru(CO)3(PPh3)2 through the reaction indicating the occurrence of decarbonylation of aldehyde. A mechanism involving the acyl-H cleavage of aldehyde is proposed to account for the catalysis and formation of compounds accompanying the reaction. The mechanism is compared with an alternative one which comprises of consecutive insertions of two aldehyde molecules into Ru–H bond followed by β-hydrogen abstraction from an alkoxo intermediate formed. Addition of water changes the reaction course to give carboxylato carbonyl complexes Ru(OCOR)2(CO)m(PPh3)2 (m=1 and 2). Cross esterif...