Study of thermal properties and swelling of the poly (2-hydroxyethyl methacrylate)-Swy-1 nanocomposite

• Grant number: 12/07573-3
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: August 01, 2012
• End date: January 31, 2013
• Field of knowledge: Physical Sciences and Mathematics - Chemistry - Organic Chemistry
• Principal Investigator: Carla Cristina Schmitt Cavalheiro
• Grantee: Bruno Diniz Fecchio
• Host Institution: Instituto de Química de São Carlos (IQSC). Universidade de São Paulo (USP). São Carlos , SP, Brazil

Abstract

Nanocomposite studies are usually focused on the methodology of their preparation, characterization of the resulting structures and investigation of thermal and mechanical properties. In this work the preparation of a methylmethacrylate derivative/clay nanocomposite will be investigated by in situ photoinitiated polymerization. The produced material will be characterized regarding its thermal and swelling properties. The n-alkyl methacrylates have a chemical structure that contain a main chain substituted by polar and nonpolar flexible side groups. Polymers formed from such compounds (poly (n-alkyl methacrylates)) have a large number of applications related to their excellent electrical and mechanical properties as well as its transparency and lightness. Poly (2-hydroxyethyl methacrylate) (PHEMA), has hydroxyl groups in its structure, therefore is a hydrophilic polymer. Since it has water content similar to the living tissue is regarded as a biocompatible hydrogel. Although PHEMA is biocompatible it were found certain compounds harmful to the human body in its bio-applications, such as HEMA monomer, which is the main product of thermal degradation of the polymer. The thermal behavior of the PHEMA and the characterization of its thermal degradation products have not been an issue extensively discussed in the literature. A review of the literature shows few studies published on this subject. The same objective of the study mentioned above is much less explored for the case of PHEMA-clay nanocomposites. An opposite situation is found in relation to the studies of the PHEMA swelling because, due to their hydrophilic characteristics, it is important to know how is the behavior of such polymer in relation to the absorption of water equilibrium, since this is a property useful in practical applications of this material. The study of the absorption and diffusion of liquid organic polymer is an area of research that has multiple applications. Among them are included the controlled drugs and pesticides release, reverse osmosis, among others. In other hand applications of crosslinked polymer system into membrane and coating technologies drives the study of these materials against liquids as an interesting issue. The behavior of absorption and diffusion of various organic solvents through a series of polymeric membranes has been studied extensively. However, this is not the case for polymer-clay nanocomposites in which only some specific cases have been investigated. In this sense, besides the preparation of PHEMA / SWY-1 nanocomposites and its chemical and structural characterization will be studied to determine the thermal degradation kinetic parameters such as activation energy and pre-exponential factor and swelling of polymer-clay nanocomposites is also a subject of this project. (AU)