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A series of main-chain polyurethanes containing sulfonyl-based NLO chromophores in the polymer backbone were prepared, the subtle structure of the chromophore moieties could be easily modified to adjust the property of the resultant polymers. The polymers exhibit improved stability of their enhanced NLO effects, besides their good processability, thermal stability, and relatively good transparency...
The study investigated shape memory properties of nanoclay-tethered polyurethane nanocomposites. Polyurethanes based on polycaprolactone (PCL) diol, methylene diisocyanate, and butane diol and their nanocomposites of reactive nanoclay were prepared by bulk polymerization in an internal mixer and the values of shape fixity and shape recovery stress were determined as function of clay content. The melting...
With the aim to control nonlinear optical (NLO) effects of polyurethanes, especially to efficiently translate the fixed μβ values of the organic chromophore to possibly higher macroscopic NLO activities of polymers, a facile synthetic strategy, consisting of the postazo coupling and esterification reactions, was developed to prepare a series of second-order nonlinear optical polyurethanes (P2–P5)...
Norbornane diisocyanate (NBDI: 2,5(2,6)-bis(isocyanatomethyl)bicyclo[2.2.1]heptane) is a new commercialized diisocyanate. NBDI-based polyurethane elastomers (PUEs) were prepared from poly(oxytetramethylene) glycol (PTMG), NBDI and 1,4-butanediol (BD) by a prepolymer method. Microphase-separated structure and mechanical properties of the NBDI-based PUEs were compared with general aliphatic and cycloaliphatic...
The molecular mechanics (MM) method with COMPASS force field was used to study the H-bonds in polyurethane with carboxyl (PUc), which has multiple donors and acceptors. 2-Methyl-3-{[(methylamino)carbonyl]oxy}propanoic acid was used as the model molecule. It was found that the model PUc possesses four conformers with lowest energy. Considering six possible H-bond types such as OH⋯OC(OH) (Type I), OH⋯OH(CO)...
The cyclic deformation of two polyurethane elastomers that differed in soft segment content and molecular weight was investigated. The microphase-separated morphology of the polyurethane with higher soft segment content consisted of hard segment domains dispersed in a soft segment matrix. In the polyurethane with lower soft segment content, the hard segment domains appeared to be partially cocontinuous...
A diisocyanate baring ether bonds, 1,2-bis(isocyanate)ethoxyethane (TEGDI), was used for the preparation of polyurethane elastomers (PUEs). The PUEs were synthesized with either TEGDI or HDI, poly(oxytetramethylene) glycol (PTMG), and curing agents by a prepolymer method. 1,6-Hexamethylene diisocyanate (HDI) was also used as a control diisocyanate. The TEGDI-based PUEs exhibited highly softened property...
The solid-state structure–property behavior of highly branched segmented poly(urethane urea) (PUU) copolymers and their linear analog was investigated. A limited study of their solution rheological behavior was also undertaken. The linear PUUs were synthesized by the two-step prepolymer method, whereas the oligomeric A 2 +B 3 methodology was utilized to synthesize the highly branched...
Poly(propylene oxide) (PPO) was incorporated in a controlled manner between poly(dimethylsiloxane) (PDMS) and urea segments in segmented polyurea copolymers and their solid state structure–property behavior was investigated. The copolymers contained PDMS segments of MW 3200 or 7000g/mol and an overall hard segment content of 10–35wt%. PPO segments of MW 450 or 2000g/mol were utilized. Equivalent polyurea...
New telechelic cis-1,4-polyisoprene oligomers bearing an hydroxyl group at the end of the polyisoprene backbone and possessing controlled molecular weights were used as soft segments in the elaboration of polyurethane elastomers. Besides, the well defined hydroxytelechelic cis-1,4-polyisoprene (HTPI) structure obtained through a controlled methodology, was chemically modified leading to hydrogenated...
Structure development in highly branched segmented polyurethaneureas based on oligomeric A 2 +B 3 approach was investigated by experimental studies and kinetic Monte-Carlo simulations. In both simulations and experiments, hyperbranched polymers were produced by the slow addition of A 2 onto B 3 . Experimental studies showed strong influence of solution concentration...
A systematic investigation was made of the effects of varying hard and soft segment chemistry, crosslinking and preparation procedures, on the mechanical response of melt-cast polyurethane elastomers. In particular, two hard segments were compared, based on the diisocyanates: 4,4′-methylene bis(phenyl isocyanate) (MDI) and 4,4′-dibenzyl diisocyanate (DBDI). Rotation around the central –CH 2 ...
The synthesis of hydroxy-terminated poly(2,2-substituted-1,3-propylene oxide) polyoxetane telechelics and co-telechelics bearing semifluorinated (–CH 2 OCH 2 (CF 2 ) n CF 3 ) and functional bromomethyl pendant groups is reported. Characterization utilized 1 H NMR spectroscopy, temperature modulated DSC (MDCS), and gel permeation chromatography (GPC)...
This third paper in this series regarding structure and dynamics of the polyurethane-based membranes studied with TEMPO spin probe presents the results of the ESR measurements performed to characterise mobility of segments in the permeable regions of the membranes. The variations of the spin probe motions with temperature have been analysed for the series of polyurethanes (PU) differing in molecular...
The cyclohexane and water permeability properties as well as the structure of the polyurethane-based pervaporation membranes were investigated. The polyurethanes (PU) were synthesised from poly(oxytetramethylene) diols (PTMO) of various molar masses, 2,4-tolylene diisocyanate (2,4-TDI), and different chain extenders used in various molar ratios. The microstructure of the synthesised PU was investigated...
Studies on the permeable regions of the dense polyurethane-based membranes were performed by electron spin resonance spectroscopy (ESR) using TEMPO spin probe incorporated into the membrane via diffusion from the vapour phase. The ESR spectra were measured as a function of temperature and microwave power for polyurethanes (PU) varying in the molecular structure and morphology. It was found that the...
Low molecular weight model trisegmented polyurethanes based on monofunctional polyols, or 'monols', with water-extended toluene diisocyanate (TDI) based hard segments (HS) are investigated. The formulations of the materials generated are similar to those of flexible polyurethane foams with the exceptions that the conventional polyol is substituted by an oligomeric monofunctional polyether of ca. 1000...
Approximately 30 years after their preparation, the nanoscale morphology of a series of ‘model’ segmented polyurethane elastomers has been further elucidated using the technique of tapping mode AFM. The materials investigated are based on 1,4-butanediol extended piperazine based hard segments and employ poly(tetramethylene oxide) soft segments. The chemistry of these polyurethanes was specifically...
Based on earlier models developed for polyaddition of diisocyanates and polyols, a non-stoichiometric process was provided for step-by-step polymerisation of 2,4- and 2,6-tolylene diisocyanate (TDI) with diols which had various molecule sizes and the nature of polyethers and polyesters. Said process yielded urethane oligomers which had -NCO or -OH groups as their chain end groups. After elimination...
Segmented copolyurethanes comprising 40–60% by weight of polyurethane hard segments (HS) and polyether soft-segment (SS) with different functionalities (SS-f n ), have been formed by reaction injection moulding (RIM). The HS were formed from 4,4′ diphenylmethane diisocyanate (MDI) reacted with ethane diol (ED). The three SS-prepolymers used were all hydroxyl-functionalised poly(oxypropylene-b-oxyethylene)s...
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