Synthesis and characterisation of soluble block copolymers from NR and TDI based polyurethanes

• Published in: Journal of materials science 2008, Vol.43 (2), p.738-747
• Main Authors: Radhakrishnan Nair, M. N, Gopinathan Nair, M. R
• Format: Article
• Language: English
• Subjects: Applied sciences; Block copolymers; Calorimetry; Characterization and Evaluation of Materials; Chemical reactions; Chemical synthesis; Chemistry and Materials Science; Classical Mechanics; composite polymers; Copolymerization; Crystallography and Scattering Methods; Differential scanning calorimetry; Diols; Elastomers; Exact sciences and technology; gel chromatography; Glass transition temperature; infrared spectroscopy; Liquid chromatography; Materials Science; Morphology; NMR; Nuclear magnetic resonance; nuclear magnetic resonance spectroscopy; Organic polymers; Physicochemistry of polymers; Polycondensation; Polymer Sciences; polymerization; Polyurethane; polyurethanes; Preparation, kinetics, thermodynamics, mechanism and catalysts; Propylene; propylene glycol; scanning electron microscopy; Segments; Solid Mechanics; Solution polymerization; Spectra; spectral analysis; Strain analysis; Stress-strain relationships; Tetrahydrofuran; Thermal decomposition; thermal degradation; Thermogravimetric analysis; thermogravimetry; Toluene; Toluene diisocyanates; Viscometry
• ISSN: 0022-2461; 1573-4803
• DOI: 10.1007/s10853-007-2198-1

Soluble block copolymers from toluene diisocyanate (TDI), with chain extender diols, viz., propylene glycol (PG), 1,4-butane diol (1,4-BDO) and 1,3-butane diol (1,3-BDO), were synthesised for the first time by solution polymerisation. Maintaining low hard segment content and keeping optimum NCO/OH ratio, formation of linear, flexible elastomers is achieved. They were characterised by spectral, thermal, microscopic and stress–strain analysis. The dilute solution properties of these block copolymers dissolved in tetrahydrofuran (THF) are studied by viscometry and gel permeation chromatography (GPC). IR and NMR spectral data support the notion that a chemical reaction leads to block copolymerisation. Differential scanning calorimetric (DSC) analysis showed a soft segment glass transition temperature around −58°C and a hard segment glass transition temperature between 75 and 70°C for these samples. This observation and two-stage thermal decomposition of the samples in thermogravimetric analysis (TGA) clearly indicate that the block copolymers are completely phase-segregated systems. SEM indicates the amorphous heterophase morphology of the samples.