Synthesis and characterization of cationomeric AB crosslinked polyurethane polymers based on different chain extenders

Synthesis and Characterization of Segmented Polyurethanes Containing Trisaminocyclopropenium Carbocations

Diol-functionalized trisaminocyclopropenium (TACP) carbocations were used as chain extenders in a two-step synthesis of a segmented polyurethane. Differential scanning calorimetry demonstrated significant differences in the crystallization behavior of the poly(tetramethylene oxide) soft segment when minor changes were made to the TACP structure and when compared to a control that was chain extended with butane diol. Fourier transform infrared spectroscopy was used to characterize the different level of hydrogen bonding in the polymers and showed that the bulky, charged TACP chain extender limited hydrogen bonding interactions when compared to the control. Dynamic mechanical analysis was used to probe the thermomechanical behavior of polymers that showed that the TACP-containing polymers were much more resistant to flow at high temperatures when compared to the control. Small-angle X-ray scattering showed a phase separated morphology for all the polymers tested. Tensile testing of the TACP polyurethanes demonstrated an elastic response over a wide range of strain, followed by a significant strain hardening. These results suggest a morphology of ionic aggregates rather than hard segment physical cross-links.

(Bio)degradable Ionomeric Polyurethanes Based on Xanthan: Synthesis, Properties, and Structure

New (bio)degradable environmentally friendly film-forming ionomeric polyurethanes (IPU) based on renewable biotechnological polysaccharide xanthan (Xa) have been obtained. The influence of the component composition on the colloidal-chemical and physic-mechanical properties of IPU/Xa and based films, as well as the change of their properties under the influence of environmental factors, have been studied. The results of IR-, PMS-, DMA-, and X-ray scattering study indicate that incorporation of Xa into the polyurethane chain initiates the formation of a new polymer structure different from the structure of the pure IPU (matrix): an amorphous polymer-polymer microdomain has occurred as a result of the chemical interaction of Xa and IPU. It predetermines the degradation of the IPU/Xa films as a whole, unlike the mixed polymer systems, and plays a key role in the improvement of material performance. The results of acid, alkaline hydrolysis, and incubation into the soil indicate the increase of the intensity of degradation processes occurring in the IPU/Xa in comparison with the pure IPU. It has been shown that the introduction of Xa not only imparts the biodegradability property to polyurethane, but also improves the mechanical properties.

Synthesis and characterization of novel linear and cross-linked polyurethane urea elastomers with 2,3-diaminopyridine in the main chain

Novel polyurethane urea containing pyridine moieties in their main chains have been prepared by a two-step solution polymerization procedure. These polyurethane urea elastomers were synthesized by chain-extending isocyanate end-capped prepolymers with 2,3-diaminoyridine and different cross-linkers. The isocyanate-terminated prepolymers were obtained from poly(tetramethylene oxide) glycol of molecular weight 1400 (Terathane 1400) and 1,6-hexamethylene diisocyanate. Including pyridine derivatives into the structural compositions leads to a change in properties that were investigated using Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), mechanical measurements and contact angle and fluorescence analysis. The results show that intermolecular hydrogen bonds have formed between pyridine groups and urethane or urea groups, affecting all the obtained properties.