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- Title
The effect of polar solvents on the synthesis of poly(urethane-urea-siloxane)s.
- Authors
BALABAN, MILICA; ANTIĆ, VESNA; PERGAL, MARIJA; FRANCOLINI, IOLANDA; MARTINELLI, ANDREA; DJONLAGIĆ, JASNA
- Abstract
Segmented poly(urethane-urea-siloxanes) (PUUS) based on 4,4'-methylene diphenyl diisocyanate-ethylene diamine (MDI-ED) hard segments and hydroxypropyl-terminated poly(dimethylsiloxane) (PDMS, ̄Mn = 1000 g mol-1 ) soft segments were prepared under various experimental conditions. The copolymers with constant molar ratio of hard and soft segments (PDMS:MDI:ED = 1:2:1; 20 wt. % of the hard segments) were synthesized in two different solvent mixtures, by a two-step polyaddition procedure. The first one was tetrahydrofuran/N,N-dimethylacetamide (THF/DMAc) with different co-solvent ratios (1/1, 1/2 and 1/9, v/v), whereas the second one was tetrahydrofuran/N-methylpyrrolidone (THF/NMP, 1/9, v/v). The reaction conditions were optimized by varying the co-solvents ratio, the concentration of the catalyst, the initial monomer concentration, as well as the time of the first and the second step of the reaction. The effects of the experimental conditions on the size of the PUUS were investigated by gel permeation chromatography (GPC) and dilute solution viscometry. The copolymers with the highest molecular weights were obtained in the THF/NMP mixture (1/9, v/v). The structure and composition of the copolymers were determined by ¹H-NMR and FTIR spectroscopy. The morphology of the synthesized copolymers was investigated by atomic force microscopy (AFM), while the thermal properties were studied by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The surface properties were evaluated by measuring the water contact angle (WCA). The copolymers exhibited phase-separated microstructure and were stable up to 200 °C in nitrogen.
- Subjects
POLAR solvents; CHEMICAL synthesis; SILOXANES; METHYLENE diphenyl diisocyanate; ETHYLENEDIAMINE; COPOLYMERS
- Publication
Journal of the Serbian Chemical Society, 2012, Vol 77, Issue 10, p1457
- ISSN
0352-5139
- Publication type
Article
- DOI
10.2298/JSC111025056B