ABSTRACT
Chemical modification of spin-cast chitosan films has been performed. This modification involves the attachment of 1,2 Epoxy-3-phenoxy-propane, commonly known as glycidyl phenyl ether (GPE), to the amine group of the chitosan molecule. Optical properties of modified films have been determined in the infrared region of the spectrum using spectroscopic ellipsometry, and are reported in this paper. Special attention is paid to the infrared region where the index of refraction and extinction coefficients from 750 to 4000 cm(-1) were determined. Difference plots of IR optical data before and after chemical modification were generated to confirm that modification had occurred. Optical modeling of infrared spectroscopic ellipsometry (IRSE) data with respect to chemical bond vibrations has also been performed. This modeling involved curve fitting of resonant chemical bond absorptions using Lorentz oscillators. These oscillator models allow for comparison of modified chitosan to unmodified chitosan. The purpose of this research was to determine infrared optical constants of chemically modified chitosan films This work shows that surface chemistry of biomaterials can be studied quite sensitively with spectroscopy ellipsometry, detecting as little as 100 ng/cm(2) of GPE.
Subject(s)
Chitosan/chemistry , Microscopy, Atomic Force/methods , Nitrophenols/pharmacology , Adsorption , Biocompatible Materials , Chitin/chemistry , Epoxy Compounds/chemistry , Epoxy Compounds/pharmacology , Membranes, Artificial , Models, Statistical , Nitrophenols/chemistry , Oscillometry , Polymers/chemistry , Spectrophotometry , Spectrophotometry, Infrared/methods , Surface Properties , Time FactorsABSTRACT
Optical properties of spin-cast chitosan films have been determined in the infrared, visible, and ultraviolet region of the spectrum using spectroscopic ellipsometry. Optical constants for the UV-vis-near IR spectra from 130 to 1700 nm were determined using Cauchy dispersion forms combined with Lorentzian oscillator models in the absorptive shorter wavelength regions. Infrared index of refraction and extinction coefficients from 750 to 4000 cm(-1) were determined using ellipsometric data fits to dispersion models based on harmonic oscillators. This modeling determined that optical anisotropy was present and measurable over all wavelength regions of ellipsometric data. To obtain information on the micro- and nano-scale surface structure, tapping mode atomic force microscopy (AFM) imaging was employed to determine morphology and roughness information of dry spin-cast chitosan films.
