James F. Kinstle

Spectroelectrochemistry of tetracyanoquinodimethane modified electrodes

Abstract Thin films of a tetracyanoquinodimethane (TCNQ) oligomer adsorbed on optically transparent platinum electrodes have been studied using spectroelectrochemical techniques. In contact with aqueous electrolytes the electron aceptor sites in these modified electrodes are reduced to mixtures of the radical aion, TCNQ ⨪ , the dimer radical anion, TCNQ 2− 2 , the dimer dianion, TCNQ 2 2− , and the dianion, TCNQ 2∮ . Electrolyte effects on the reduction process and the stability of the reduced films were studied. Both monovalent and divalent ions exhibited Nernstian potential dependence, and in the presence of Ca 2+ ions the dianion state was stabilized. Counterion effects are suggested as the origin of variations in the wave shape in multcycle voltammograms.

Homogeneous Chemical Modifications of Cellulose: Further Studies on the DMSO-PF Solvent System

A great deal of attention has been given to basic and applied research on cellulose, since it has outstanding physical and chemical properties, including the capability of being transformed into a great variety of products like fibers, films, papers, plastics, food additives, etc. Also, cellulose is obtained from renewable resources, principally from trunks of trees and cotton.

SYNTHESIS AND CHARACTERIZATION OF LINEAR AND CROSSLINKED AB-TYPE POLYURETHANES

Novel AB-type polyurethanes have been prepared. Six of these contain in-chain aromatic units and have generic formula I, including ortho-substituted structures with m, n combinations of (1,0), (0,1), (1,1), (0,2) and para-substituted structures with m, n combinations of (0,0) and (0,2). The aliphatic was prepared for comparison. Ortho (0,0) could not be prepared by either the decomposition-intermolecular reaction of the hydroxy acylazide (cyclic benzoxazolinone was formed) or by thermal ring-opening of the benzo-substituted cyclic carbamate. Ortho (1,0) and (0,1) could be prepared by either route, though ring formation was favored in the Curtius reaction. Thermal polymerization of the cyclic benzoxazinones under mild conditions formed the amorphous linear polyurethanes; upon polymerization at high temperature or upon heating of the linear polymers, crosslinked materials were obtained, with urea, isocyanurate, and diarylmethane and polymerized carbodiimide moieties, respectively, being favored as the temperature was increased. Crystalline ortho (1,1), amorphous ortho (0,2), and crystalline para (0,0) and (0,2) could be prepared in good yield by the Curtius route; again the crosslinked structures progressively increased with post-polymerization heating. Infrared spectroscopy in the “near IR” range was found to be a valuable supplement in characterization of these polymeric materials.

Photoassisted Modification of and Grafting to Polyethylene

Polyethylene (PE) is widely used in a number of applications, due to a combination of low cost, desirable mechanical properties, low permeability, low surface energy characteristics, etc. Yet in other potential applications, modification of the surface of the polymer - without significant alteration of bulk chemical or physical properties - would be advantageous. For example, the low surface energy of PE (1) is useful in several applications but contributes to low adhesion of inks, coatings, and adhesives. The PE surface can be roughened or micropitted in order to enhance physical interlock type adhesion (2), but the interfacial strength and permanence could be markedly enhanced by formation of chemical bonds or grafts to the PE substrate. This new grafted surface may be comprised of the coating, ink, or adhesive, or it may just exhibit physical or chemical properties different from the PE, thereby allowing better wetting or bonding in a subsequent step.