Synthesis, characterization, and cyclic stress-influenced degradation of a poly(ethylene glycol)-based poly(beta-amino ester)

This study aims to fundamentally understand polymer network formed by poly(ethylene glycol) diacrylate (PEGDA) MW 700 and 3-methoxypropylamine (3MOPA) as well as to characterize the degradation response of this material with and without applied cyclic stress. Macromer reaction chemistry was confirmed by H-1 NMR measurements. UV calorimetry analysis revealed conditions of network formation were dependent on molecular weight of the PEGDA monomer and light intensity. The glass transition temperature of all networks PEGDA MW 258, 575, and 700 were measured and found to be in the range of -40 to -30 degrees C with a rubbery moduli ranging from 4 to 1.0 MPa by DMA. Degradation studies were performed with and without applied cyclical stress, and in most cases, elastic modulus decrease and mass loss occurred steadily over a 24-h period. Unexpected partial crystallization was discovered to occur in the networks containing higher molecular weight PEGDA in the presence of humidity and high frequency cyclic loading. In all materials, high frequency applied cyclic loading during in situ degradation resulted in catastrophic fracture of the material prior to an appreciable decrease in modulus. (C) 2009 Wiley Periodicals, Inc. J Biomed Mater Res 92A: 702-711, 2010