Superstructure in segmented polyether–urethanes

Wiley - Tập 13 Số 3 - Trang 455-476 - 1975
Yaw‐Jen Chang1, Garth L. Wilkes2
1Department of Chemistry, Princeton University, Princeton New Jersey 08540
2Department of Chemical Engineering Polymer Materials Program Princeton , University Princeton , New Jersey, 08540

Tóm tắt

AbstractThe morphology of several series of segmented polyether–urethanes was studied. The “hard” segments contained urethane and urea linkages formed by 4,4′‐dicyclohexylmethane diisocyanate (Hylene W) and selected aliphatic and aromatic monomeric diamines (DA). The “soft” segments were composed of oligomeric poly(ethylene oxide) (PEO), poly(propylene oxide) (PPO), or both PEO and PPO. For studying the composition–morphology relationships, the molecular weight and relative content of PEO, and the relative content of PPO were varied systematically. Different diamines were used as chain extenders. The methods of wide‐angle x‐ray diffraction (WAXD), small‐angle x‐ray scattering (SAXS), polarizing microscopy, scanning electron microscopy (SEM), and differential scanning calorimetry (DSC) were employed in the investigation. The effects of PEO content on domain formation were very significant. Calculations based on a highly simplified model indicated that, for two adjacent molecules, if two hard segments are associated with each other, the probability for the association of the next two hard segments varies inversely with the third power of soft segment length. Copolymers composed of both POE and PPO displayed enhanced domain and anisotropic superstructure. The phenomenon was interpreted in terms of polymer incompatibility. The effects on morphology of different DA's as chain extenders were tentatively accounted for by the symmetry, hydrogen bonding, and rigidity of the hard segments as well as their incompatibility with the soft segments. The formation and deformation of superstructure were of particular interest. A model was proposed to account for the formation of the resultant anisotropic structure and mechanical properties.

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Wiley

Tập 13 Số 3

455-476

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