Segmented Poly(urethane-urea)s Synthesized Directly from Isocyanate-Terminated Prepolymers and Masked Diamines I. Quantitative Synthesis

Abstract

ABSTRACT:An attempt was made for quantitative synthesis of segmented poly(urethane-urea)s (PUUs), not via solution state, but directly from an isocyanate-terminated prepolymer prepared from an excess molar concentration of 4,4'-methylenediphenyldiisocyanate with poly(tetramethyleneoxide) (M.=2010) and reaction products from acetone and ethylenediamine (EDA) consisting of N-isopropylideneethylenediamine (I), N,N'-diisopropylideneethylenediamine (2), 2,2-dimethylimidazolidine (3) as main product, water, and the unreacted raw materials. With increasing the masking ratio of acetone to EDA, the concentrations of the ketimine groups and water increase while those of the imidazolidine and EDA generally decrease, the molar fraction of the by-product from the reaction of an isocyanate group with water was increased mainly because of the catalytic effect of the ketimine groups. Acetic acid played the significant roll to eliminate the side reaction by accelerating disappearance rate of (I) ((2)) and the quantitative yield of PUU was attained at 40°C when the acid concentration and the masking ratio were 3.50 x 10-3 mo! kg-1 and 1.4, respectively.KEY WORDS Poly(urethane-urea)s / Bulk Polymerization / Quantitative Yield/ Isocyanate-Terminated Prepolymer / Masked Diamines /Water/ Acid/ Segmented poly(urethane-urea)s (PUUs) compose of a class of elastomers exhibiting superior extensibility, toughness and durability over segmented poly(urethane)s and are extensively used in the fields from textile fibers to medical prosthesis.

Influence of Hard Segments to Specific Refractive Index Increments of Segmented Poly(Ester Urethane)s

“…[11] The combination of polyols with diissocyanates and low molecular chain extenders gives rise to a multitude of forms suited to extremely different practical applications as fibers, paints, foams, resins, elastomers, etc. [11] The combination of polyols with diissocyanates and low molecular chain extenders gives rise to a multitude of forms suited to extremely different practical applications as fibers, paints, foams, resins, elastomers, etc.…”

Segmented Poly(urethane-urea)s Synthesized Directly from Isocyanate-Terminated Prepolymers and Masked Diamines II. Kinetic and Mechanistic Study on Masking and Demasking Reaction

“…1 The emphasis was laid on the methodological study to eliminate the by-product (Urea II) arising from the reaction of an isocyanate (NCO) group with water catalyzed by the ketimine and the imino groups. Acetic acid played a significant roll for vanishing Urea II, leading to the quantitative yield of the desired urea group, Urea I.…”

Synthesis and characterization of excellent transparency poly(urethane‐methacrylate)

“…[5][6][7][8][9][10][11][12] Therefore, macromonomer has been widely applied in coating, inks, dry toners, instrument calibration, chromatography, and biomedical treatment etc. [13][14][15][16][17][18][19][20][21] Polyurethane is an important material in optics, 22 automotive parts, 23 and optoelectronics 24,25 for its outstanding properties, such as transparence in a wide wavelength range, strong damage resistance for laser irradiation, good physical properties, high heat-proof thermal properties, chemical stability, good dimensional stability, etc. PUA elastomers represent a new class of polyurethanes which contain ''soft'' segments formed from polyester or aliphatic polyether chains, and ''hard'' segments formed from urethane groups and acrylic structural units.…”