Kiyohide Matsui

(Diethylphosphinyl)difluoromethyllithium. — Preparation and synthetic application —

Abstract The action of lithium diisopropylamide on diethyl difluoromethylphosphonate gives the title reagent which reacts with various electrophiles to introduce difluoromethylene or difluoromethyl unit.

Chemical modification of polysulphone: 2. Gas and liquid permeability of polysulphone/polydimethylsiloxane graft copolymer membranes

Abstract The gas and liquid permeabilities of polysulphone/polydimethylsiloxane (PSF/PDMS) graft copolymer membranes have been investigated. The permeability coefficients to nitrogen, oxygen, hydrogen, methane and carbon dioxide were evaluated. The gas permeability coefficients of the graft copolymer membranes were influenced by the PDMS content of the graft copolymer. In the region of >60wt% PDMS content, the oxygen permeability coefficient of PSF/PDMS graft copolymer membrane was (1−3) × 10 −8 cm 3 cm cm −2 s −1 cmHg −1 . In addition, the permeability to methane and carbon dioxide was remarkably enhanced in comparison with PSF membrane. The introduction of PDMS chains greatly increased the diffusion coefficients of methane and carbon dioxide. In the case of pervaporation of aqueous ethanol solution, the preferential permeation of ethanol was observed through the graft copolymer membrane for which the PDMS content was >50wt%.

Chemical modification of polysulphone: 1. Synthesis of polysulphone/polydimethylsiloxane graft copolymer

Abstract In order to improve the gas and liquid permeability of polysulphone (PSF) membrane, a chemical modification of PSF was achieved by introducing a polydimethylsiloxane (PDMS) chain to afford PSF/PDMS graft copolymer. The graft copolymer was prepared by hydrosilylation of vinylsilylated PSF with hydrosilyl-terminated PDMS oligomer. The vinylsilylated PSF was prepared by metallation of PSF with n-butyllithium followed by treatment with dimethylvinylchlorosilane. The hydrosilyl-terminated PDMS oligomer was prepared by an anionic ring-opening polymerization of hexamethylcyclotrisiloxane with n-butyllithium followed by termination with dimethylchlorosilane. PDMS content of the graft copolymers could be controlled in the range of 18 to 80wt% by changing the silylation rate of vinyldimethylsilylated PSF or the degree of polymerization of hydrosilyl-terminated PDMS oligomer. Very tough and thin membranes could be prepared from the graft copolymers by using a solvent casting method. Solubility and mechanical properties of the graft copolymer were evaluated in comparison with PSF.

Synthesis and gas permeability of poly(tetramethyl-p-silphenylenesiloxane)polydialkylsiloxane) block copolymers containing fluoroalkyl substituents

Abstract Poly(tetramethyl -p- silphenylenesiloxane) poly(dialkylsiloxane) (PTMPS/PDAS) block copolymers containing various kinds of fluoroalkyl substituents were synthesized. The gas permeability of the copolymer membranes was evaluated. The PTMPS contents of the copolymers could be controlled in the range 20–80 mol%, and the weight average molecular weights were more than 10 5 . Very tough and thin membranes could be prepared from these copolymers by a solvent casting method. The oxygen permeability coefficient P O 2 of the copolymer membranes increased as PTMPS content decreased, and was independent of the kinds of substitution. When PTMPS content was below 40 mol%, the P O 2 of every copolymer membrane was more than 1 × 10 −8 cm 3 (s.t.p.) cm cm −2 s −1 cmHg −1 . The fluoroalkyl substituents affected the selectivity P O 2 P N 2 . The values of P O 2 P N 2 for PTMPS/PDAS block copolymers were higher than those of PTMPS/poly(dimethylsiloxane) block copolymers, which did not contain the fluoroalkyl group. Some of these copolymers showed excellent oxygen permselectivity, with values of P O 2 and P O 2 P N 2 in the range 10 −8 −3 × 10 −8 cm 3 (s.t.p.) cm cm −2 s −1 cmHg −1 and 2.30–2.50, respectively.

Preparation of a polymer containing hexadecylpyridinium bromide groups and its utilization as a transdermal drug penetration enhancer

Abstract A novel polymeric transdermal penetration system was investigated. The polymer was synthesized by the reaction of poly(4-vinylpyridine) and hexadecyl bromide, and its enhancing activity on drug penetration was evaluated by means of in vitro experiments. The amount of 5-fluorouracil (5-FU) that permeated through the skin was determined by using a two-chamber diffusion cell, in which isolated rabbit abdominal skin was mounted. Addition of the polymer effectively enhanced the penetration rate of 5-FU. The permeability coefficient was 2–8 times as much as that in the absence of the polymer. The enhancing activity increased with increase in the degree of quaternization. The mechanism was investigated by differential scanning calorimetry of whole skin and stratum corneum treated with the polymer. Through this investigation, it was shown that, although the polymer interacted with the lipids and proteins of the membranes of the stratum corneum, it may not penetrate into deeper layers of the skin. The absence of irritation of the polymer to the skin was confirmed by the Draize test.