Evolution of molecular relaxations in poly(2-(2-methoxyethoxy)ethyl methacrylate) upon network formation by ATRP

Copolymers of 2-(2-methoxyethoxy)ethyl methacrylate (MEO2MA) and oligo(ethylene glycol) methacrylate (OEGMA) are attractive stimuli-responsive materials for biomedical applications because of their nontoxicity and nonimmunegeniverity and sharp and insensitive to environmental conditions volume phase transition observed for poly(MEO2MA). The mechanism of this transition in poly(MEO2MA) are still not explained sufficiently, what is necessary in order to find the way to accelerate water sorption/desorption transitions of this polymer. Considering the fact that the kinetics of mixing/demixing of polymer-water systems should be partially stimulated by the dynamics of polymer chains, this work is focused on the relaxation processes in several poly(MEO2MA)-based systems. The comparison of dynamical behavior of poly(MEO2MA)-based materials with different molecular architecture (linear polymer, and two polymer networks – simple and grafted by additional poly(MEO2MA) chains) was done. Calorimetric, dielectric and mechanical analysis show that glass transition temperature (Tg) of the investigated materials based on poly(MEO2MA) is practically independent on the network architecture. The relaxation process marked a, observed in both dielectric spectroscopy and dynamic mechanical analysis above Tg, is assigned to the segmental movements, while another one, marked α’, is assigned to the movements of whole poly(MEO2MA) network. It is shown that this process correlates well with the observed in poly(MEO2MA) hydrogels volume phase transition. Besides this two high-temperature molecular relaxations, three secondary relaxations correlated with local group dynamics were observed by dielectric spectroscopy. 
 

Martes, Febrero 26, 2013 - 12:00
Jacek Ulanski
Department of Molecular Physics, Lodz University of Technology, Zeromskiego 116, 90-924 Lodz, Poland
Sala 317
Seminar