Anna Kultys

New thermoplastic polyurethane elastomers based on sulfur-containing chain extenders

Abstract New thermoplastic polyurethane elastomers (TPUs) were synthesized by a one-step melt polyaddition from poly(oxytetramethylene) diol of M¯n = 2000 g/mol as the soft segment, 1,1’-methanediylbis(4-isocyanatocyclohexane) (HMDI, Desmodur W®), and 2,2’-[methanediylbis(benzene-4,1-diylmethanediylsulfanediyl)]diethanol (diol E) or 6,6’-[methanediylbis(benzene-4,1-diylmethanediylsulfanediyl)]dihexane-1-ol (diol H) as unconventional chain extenders. The effects of the kind and amount of the polymer diol and chain extender used on the structure and properties of the polymers were studied. The polymers were examined by Fourier transform infrared spectroscopy, gel permeation chromatography, thermogravimetric analysis, differential scanning calorimetry, Shore hardness and tensile testing. Both the adhesive and optical properties were determinated for a selected polymer. The obtained TPUs were amorphous, colorless, high-molar-mass materials. It was observed that the polymers with the diol E showed higher hardness and tensile strengths but smaller elongations at break than diol H-based ones. All of the polymers exhibited a relatively good thermal stability. Their temperatures of 5% mass loss were in the range 312-338°C.

Polymers containing sulfur in the side chain

We synthesized new thiodicarboxylic acids, p-tolylmethylthiomethylsuccinic acid and 1-naphthylmethylthiomethylsuccinic acid, and thiodiols, 2-(p-tolylmethylthiomethyl)-1,4-butanediol and 2-(1-naphthylmethylthiomethyl)-1,4-butanediol, by the addition of dimethyl itaconate with p-tolylmethanethiol or 1-naphthylmethanethiol, followed by hydrolysis or reduction, respectively, of the resultant dimethyl esters. These difunctional monomers were used for the synthesis of new linear polyesters and polyurethanes containing sulfur in the side chain. The polyesters were synthesized by melt polycondensation of the obtained acids with 2,2′-oxydiethanol. We found reduced viscosity, molecular weight (by GPC), and softening temperature for the reaction products. Low molecular weights, low softening temperature, and very good solubility in organic solvents are their characteristics. The polyurethanes were prepared by polyaddition diols with hexamethylene diisocyanate and tolylene diisocyanate in benzene. They were characterized by reduced viscosity and some tensile properties. The polyurethane derived from 2-(p-tolylmethylthiomethyl)-1,4-butanediol and hexamethylene diisocyanate (ηred. 1.17 dL/g) behaves like a high elasticity thermoplastic elastomer. Thermal stability of all polymers was determined by thermogravimetric analysis. The structure of the monomers and polymers were confirmed by elemental analysis and FTIR and 1H-NMR spectroscopy.

Influence of DMPA content on the properties of new thermoplastic poly(ether-urethane) elastomers

New thermoplastic poly(ether-urethane) elastomers were synthesized by one-step melt poly addition from poly(oxytetramethylene)diol of M ¯ n = 2000 g mol−1 as soft segment, 1,1′-methanediylbis(4-isocyanatocyclohexane) (Desmodur W®), and 2,2′-methylenebis[(4,1-phenylene)methylenesulfanediyl]diethanol or 6,6′-methylenebis[(4,1-phenylene)methylenesulfanediyl]dihexan-1-ol as unconventional chain extenders, and 3-hydroxy-2-(hydroxymethyl)-2-methylpropanoic acid as an ionic chain extender. The structure of polymers was examined by attenuated total reflection Fourier-transform infrared. Moreover, their thermal behavior, Shore A/D hardness, mechanical properties, and optical and adhesive properties were determined. Addition of carboxyl groups to polymer resulted, generally, in increased transparency, hardness, tensile strength and adhesive strength on copper polymer junction and decreased thermal stability, refractive indexes, elongation at break, and modulus of elasticity.