Luc Ubaghs

Synthesis and characterization of alternating poly(amide urea)s and poly(amide urethane urethane)s from ε-caprolactam, diamines, and diphenyl carbonate or ethylene carbonate

Abstract Alternating poly(amide urea)s from ε-caprolactam, diamines H2N-(CH2)x- NH2 (x = 2 - 4), and diphenyl carbonate were prepared in two steps. The microstructure of the poly(amide urea)s, as determined by means of 1H NMR spectroscopy, reveals a strictly alternating sequence of the building blocks. The molecular weights and polydispersities obtained were 7500 < Mn < 10 000 and 1.48 < Mw/Mn < 1.56, respectively. Thermal properties were determined by means of differential scanning calorimetry (DSC) (163.9°C < Tm < 197.2°C; 55.5°C < Tg (2nd heating) < 72.2°C), and thermogravimetric analysis (TGA). TGA shows a three-step decomposition at 200, 350, and 450°C, which was attributed to the cleavage of O-phenyl urethane end groups, as well as urea and amide linkages. These assignments were made by comparison with model compounds. Furthermore, alternating poly- (amide urethane urethane)s from ε-caprolactam, diamines, and ethylene carbonate were prepared in three steps. The microstructure of the poly(amide urethane urethane)s, as determined by means of 1H NMR spectroscopy, reveals imperfections. The molecular weights and polydispersities obtained were 5400 < Mn < 17 000 and 2.08 < Mw/Mn < 2.99, respectively. Thermal properties were determined by means of DSC (155.9°C < Tm < 159.0°C; 35.5°C < Tg (2nd heating) < 39.0°C) and TGA. TGA shows a complex decomposition due to the formation of ethylene carbonate by cleavage of the urethane groups (at approx. 230°C) and formation of poly(amide urea)s. The newly formed poly(amide urea)s decompose in a similar way as the poly(amide urea)s.

Textural properties of poly(glycidyl methacrylate): acid-modified bentonite nanocomposites

The aim of this study was to obtain enhanced textural properties of macroporous crosslinked copolymer poly(glycidyl methacrylate-co-ethylene glycol dimethacrylate) by synthesizing nanocomposites with acid-modified bentonite. Nanocomposites were obtained by introducing various amounts of acid-modified bentonite (BA) into the reaction system. All samples were characterized by attenuated total reflectance infrared spectroscopy, scanning electron microscopy, transmission electron microscopy (TEM), mercury intrusion porosimetry, and low temperature physisorption of nitrogen. The FTIR and TEM analysis confirmed incorporation of BA into the copolymer structure and the successful formation of nanocomposites. TEM images confirmed formation of nanocomposites having both intercalated and exfoliated acid-modified bentonite in copolymer matrix. A significant increase of specific surface area, pore volume, and porosity of the nanocomposites in comparison to the copolymer were obtained. The difference between textural properties of nanocomposites with different amounts of incorporated acid-modified bentonite was less prominent.