Dr. Manit Rappon
Physical Chemistry & Photochemistry
|Office Phone:||(807) 343-8262|
|Lab Phone:||(807) 343-8587|
c/o Lakehead University
My research can be divided into three different areas:
(a) Electrodilatometry (ED)
This is a new technique developed in our laboratory. A liquid sample of interest in an ED cell is subjected to high electric field and the change in volume of the sample is monitored automatically. ED is a pervasive technique and can be applied to study numerous liquids and solutions, ranging from small molecules to supramolecular structures. It has since been used to study pure and binary mixtures of liquids as well as solutions of surfactants. We are extending this technique to study solutions of polymers and biopolymers. More details on ED may be found in J. Mol. Liquids, 80, 65-76 (1999).
(b) Photochromism and Photochromic Reactions in Liquids and in Polymer Matrices
Photochromic dyes are very important and they have been utilized in many photonic applications such as erasable optical memory, imaging, optical switches, chemical-gated molecular devices, and other high-tech applications. Invariably, many applications are carried out in polymer media. In order to understand these processes better, we have investigated the roles of microenvironment and polymer free volume and how they can influence the course of a photochromic reaction. For comparison to reaction in rigid polymer media, reaction in solution has also been conducted. In an attempt to increase the storage capacity of an optical memory media, more than one photochromic dye has been used by various groups. We are investigating the photochemistry of the dual photochromic dyes in order to gain some basic insight on such a system.
(c) Hydrogen Bonds in Liquids and Solutions
Hydrogen bonding plays important roles in physico-chemical and biological systems. Hydrogen bonds are important in catalyzing chemical reactions, microemulsions, miscibility of polymer blends, enantioselectivity of enzyme reactions, dynamic of proton transfer, molecular recognition, supramolecular assemblies, etc. While many attempts have been made to investigate this topic, the basic understanding at molecular level is illusive and far from adequate. We have investigated molecular association of some alcohols in binary mixtures, employing several physical techniques. Recently, we have extended our studies to hydrogen-bonded nonionic surfactants.
M. Rappon and R.M. Johns, "Molecular association of pentanols in n-hehtane V: Electrodilatometric effect", J. Mol. Liquids, 80, 65 (1999).
M. Rappon, R.T. Syvitski, "Kinetics of photobleaching of of Aberchrome 540 in various solvents", J. Photochem Photobio. A: 93, 243 (1996).
M. Rappon, K. M. Ghazalli and S. Rochanakij, " Photo-induced reaction of dye in polymer media-V: Low-temperature photobleaching of Aberchrome 540 in polymer matrices", Eur. Polym. J., 33, 1689 (1997).