Infrared Dichroism Study of Segmented Polyurethaneurea with Triblock Polyether Soft Segments

Abstract

ABSTRACT:Infrared (IR) dichroism study of segmented polyurethaneurea (SEUU) with ABA type triblock copolymer as a soft segment was carried out, where A stands for poly(oxyethylene) (PEO) and B stands for poly(oxytetramethylene) (PTMO). IR dichroism analysis of SEUU films under elongation suggested that the introduction of PEO units to the ends of PTMO brought about more aggregation of the hard segments, i.e., the better microphase separation in SEUU than segmented polyurethaneurea (SPUU) prepared from PTMO. Under uniaxial extension, the crystalline hard segment domain oriented transverse to the stretch direction at early stage, the degree of orientation being larger with the increase of PEO content. The larger was the PEO content, the better the microphase separation in SEUU.

Fast-Tracking of the Segmental Orientation in Poly(ethylene oxide)-based Polyurethane Urea by Mechano-optical (Infrared Dichroism and Birefringence) Properties: Degree of the Soft-Segment Ordering Effect

“…The soft segments directly respond to stretching with a linear increase in the positive chain orientation as a function of strain, whereas hard-segment orientation function values remain zero before the onset of positive orientation at point E for PEO5-30. This behavior of hard segments was explained as the compensation of positively orienting small fibrillar hard segments by the negatively orienting lamellar hard-segment domains . There is slight positive orientation between E and F in fibrillar hard segments, and that continuous in soft segments marks the onset of a birefringence increase.…”

“…Multicomponent thermoplastic polyurethanes consisting of alternating hard and soft segments offer unique mechanical properties that strongly depend on their backbone structure, composition, and resultant microphase morphologies. Even though these segments are semi-continuous, it was found that they exhibit distinctly different orientation responses to deformation. − Rinke and Oertel conducted pioneering studies on the deformation behavior of stretched elastic polyurethanes using offline X-ray diffraction. Later, Cooper and Tobolsky used a torsional testing apparatus to find the origin of enhanced modulus on plasticizer-loaded polyurethane films .…”

“…Although many other publications exist on the effect of deformation to structural orientation assessment through offline measurements, − they provide limited understanding on the real-time material response. Nomura and co-workers have also carried out extensive studies on the IR dichroism of a wide range of polyurethanes, , Therefore, the real-time studies have gained importance since they were able to capture deformation effects more accurately.…”

High-Strength Heat-Elongated Thermoplastic Polyurethane Elastomer Consisting of a Stacked Domain Structure

“…The HS and SS are self-assembled at a nanometer scale due to microphase separation caused by the thermodynamic incompatibility between them. The microphase-separated structure depends on the HS content [ 6 , 7 , 8 , 9 , 10 ] and chemical structure [ 11 , 12 , 13 , 14 , 15 , 16 ], and can be changed by thermal annealing [ 17 , 18 , 19 , 20 , 21 , 22 ]. Since the HS domain acts as a physical cross-link point, the tensile property is correlated with the microphase-separated structure.…”

Synthesis and properties of main‐chain liquid crystalline polyurethane elastomers

“…Alternatively, they can consist of rigid units joined by flexible spacers that show thermotropic behavior on heating.' On the CCC 0021 -8W5/94/020207- 12 other hand, thermoplastic polyurethane elastomers are block copolymers of the ( A-B ) , type, consisting of alternating soft and hard segments. At service temperatures, the soft segment is in a viscous or rubbery state, whereas the hard segment is in a glassy or semicrystalline state.…”