Abstract: A sensor device is disclosed, as well as methods and systems for determining a barrier property of each coating of an array of barrier coatings deposited onto a fluid-permeable or fluid-impermeable substrate. The systems and methods include the sensor device having a sensing layer responsive to a fluid of interest for which the barrier property of the array of coatings are desired to be determined. The sensor device further includes an overlayer disposed between the array of barrier coatings and the sensing layer. The overlayer protects the sensing layer from being damaged by the coatings.

Abstract: A sensor device is disclosed, as well as methods and systems for determining a barrier property of each coating of an array of barrier coatings deposited onto a fluid-permeable or fluid-impermeable substrate. The systems and methods include the sensor device having a sensing layer responsive to a fluid of interest for which the barrier property of the array of coatings are desired to be determined. The sensor device further includes an overlayer disposed between the array of barrier coatings and the sensing layer. The overlayer protects the sensing layer from being damaged by the coatings.

Abstract: Silylmethanethiols have been found to be useful promoters in the acid catalyzed condensation reaction between phenol and acetone to afford bisphenol A. Silylmethanethiols provide improvements in both the rate and selectivity of bisphenol A formation relative to known thiol promoters such as 3-mercaptopropionic acid or hexanethiol.

Abstract: A method for preparing bisphenol A is disclosed, with a selectivity for the p,p′-isomer of greater than about 97%. The method involves reacting phenol with p-isopropenylphenol or 2-(4-hydroxyphenyl)-2-propanol in the presence of a catalyst, at a reaction temperature of no greater than about 65° C. The bisphenol A product is preferably purified by a technique which omits the use of adduct crystallization.

Abstract: The invention relates to polycarbonates suitable for use in optical articles; the polycarbonates contain residues of alicyclic bisphenols and have properties particularly suited for use in high density optical data storage media. The polycarbonates further contain residues of other monomers, such as SBI and its derivatives; bisphenols, such as bisphenol A; CD-1 and its derivatives or some combination of each.

Abstract: A method for preparing bisphenol A is disclosed, with a selectivity for the p,p'-isomer of greater than about 97%. The method involves reacting phenol with p-isopropenylphenol or 2-(4-hydroxyphenyl)-2-propanol in the presence of a catalyst, at a reaction temperature of no greater than about 65.degree. C. The bisphenol A product is preferably purified by a technique which omits the use of adduct crystallization.

Abstract: A method for recovering substantially pure p,p-bisarylols from a mixture comprising the same by subjecting the mixture to vacuum distillation and melt crystallization in the absence of an adduct crystallization and the generation of a reaction recycle stream.

Abstract: Polyimides, especially thermoset polyimides such as those prepared by the reaction of p-phenylenediamine with 4,4'-hexafluoroisopropylidenebis(phthalic anhydride) and nadic ester, are converted to monomers which may be recycled for polyimide synthesis by heating with a solution of an alkali metal hydroxide, such as lithium hydroxide or sodium hydroxide, in a dipolar aprotic solvent such as N-methylpyrrolidone. The products are the diamine and the tetracarboxylic acid alkali metal salt corresponding to the dianhydride.