Supramolecular structure of crosslinked polyurethane elastomers based on well‐defined prepolymers

Abstract

This article provides both quantitative and qualitative evaluations of supermolecular structures present in segmented polyurethane elastomers. This work presents our recent results from investigation of the microdomain morphology of poly-(ether-urethanes) based on polyethylene glycol and poly-(ester-urethanes) based on poly-e-caprolactone diol with different molecular weight as soft segments and hard segments based on the combination of TDI and triethanolamine or 4,4 0 ,4 00 -triphenylmethane triisocyanate (Desmodur RE). Those PU elastomers were obtained not only in a typical one-step method but also in the prepolymer method with the use of urethane oligomers with controlled molecular weight distribution (MWD). Prepolymers with well-defined chain structures and narrow distributions of their molecular weights (MWD) M w =M n ¼ 1.1-1.6 were produced in a multistage method, i.e., in step-by-step polyaddition of 2,4-and 2,6-TDI with polyoxyethylenediols or polycaprolactonediols of different molecular weights. Isocyanate oligomers obtained at individual stages were then crosslinked with triethanolamine, whereas hydroxyl-terminated oligomers were crosslinked with Desmodur RE. Microdomain morphology of the soft and hard-segments structure was characterized by means of wide-angle Xray scattering and scanning electron microscope. The phase morphology and microdomain crystallinity were investigated.

Design, polymerization, and properties of polyurethane elastomers from miscible, immiscible, and hybridized seed‐oil derived soft segment blends

“…Properties of control elastomers made from unblended seed‐oil and petrochemical derived soft segments exhibited properties consistent with innumerable prior research results . The elastomers exhibit soft segment glass transition properties consistent with the glass transition of the soft segment and the amount of dissolved hard segment within the soft segment (Fig.…”

Preparation and characterization of nanocomposites made from chemoenzymatically prepared polyester urethanes and functionalized multiwalled carbon nanotubes

“…In neat PU (Fig. A), microphase separations can be observed, between continuous phase which is created by the soft segment and the disperse phase made for rodlike shape particles generated by the association of hard segments on crystalline sections of the soft segments . The Fig.…”

Synthesis, phase behavior, and simulated in vitro degradation of novel HTPB-b-PEG polyurethane copolymers

“…Pilch-Pitera et al deemed that the formation of the phase-separation structure is contrib- uted to three principal thermodynamic factors: mobility of hard segments, viscosity of the system and hydrogen bonding interactions between hard segments. 17 At the same time, we also notice that the particle size of the alternating block copolymers, HTPB-alt-PEG 600 and HTPB-alt-PEG 1000 , is smaller than their counterparts, HTPB-co-PEG 600 and HTPB-co-PEG 1000 , and the intermediate phase interface is smoother than the random block copolymers, demonstrating their low microphase separation degree. It is likely that more regular arrangement of soft segments from the alternating copolymers is responsible for it, which possibly causes the phase mixing and in turn lowers degree of phase separation.…”