Joseph L. Lippert

In situ polymerization of tetraethoxysilane in polymers: chemical nature of the interactions

Abstract The formation of molecular composites by the in situ polymerization of tetraethoxysilane in various organic polymers has been studied. The results show that highly homogeneous, transparent composites can be formed for polymers such as poly (methyl methacrylate), poly (vinyl acetate), poly (vinyl pyrrolidone), and poly (N,N-dimethylacrylamide). These composites have improved mechanical properties and increased solvent resistance. Strong interactions between the SiO2 networks and these polymers were observed, and the data suggest hydrogen bonding between residual hydroxyls on the SiO2 and carbonyl groups on the polymer chains as the major source of these interactions.

Interactive self-modeling multivariate analysis

Abstract Windig, W., Lippert, J.L., Robbins, M.J., Kresinske, K.R., Twist, J.P. and Snyder, A.P., 1990. Interactive self-modeling multivariate analysis. Chemometrics and Intelligent Laboratory Systems, 9: 7–30. In many practical applications in a laboratory, the data output from the analytical instruments is very complex. For example, a series of spectra following a reaction in time may contain information on intermediate and/or new products, of which no model spectra are available. In these kinds of cases, such standard data analysis tools as librrary search or subtraction methods cannot be applied. In order to analyze this type of data properly, self-modeling multivariate data analysis techniques have been developed. These techniques are capable of extracting spectra of the pure components from a data set of mixtures, without using prior knowledge of the pure components. This paper will explain a new approach for self-modeling multivariate analysis. The techniques involved will be explained by geometrical means. Examples of analyses of the data resulting from monitoring reactions in time will be shown. The first data set consist of Raman spectra monitoring the formation of silica glasses from a solution. The second data set consists of Fourier transform infrared data monitoring a reaction that produces a widely used ingredient in photography. The data have been analyzed with the Interactive Self-modeling Multivariate Analysis (ISMA) package, which is a higly interactive graphics oriented set of programs developed for this approach.

Base Hydrolysis Of Poly{Bis(Trifluoroethoxy)Phosphazene}

Abstract The base hydrolysis of high molecular Weight poly{bis(trifluoroethoxy)phosphazene} (I) is an effective method for the incorporation of hydroxy groups onto the phosphorus-nitrogen backbone (II). Incorporation of greater than 7 mole% hydroxy groups yields a semi-crystalline film-forming material. The hydrolysis has been modeled using the cyclic trimer {N3P3(OCH2CF3)6} (III). Comparisons of the 1H NMR spectra of hydrolyzed trimer {N3P3(OCH2CF3)5(OH)} (IV) and the high polymer II allow for the facile monitoring of the extent of hydrolysis. Titration with a Strong base shows the hydroxy groups to be strongly acidic. Viscosity measurements show some loss of molecular weight upon hydrolysis.