Scanning and transmission electron microscopy studies on a model series of spherulitic segmented polyurethanes

Microthermal Characterization of Segmented Polyurethane Elastomers and a Polystyrene−Poly(methyl methacrylate) Polymer Blend Using Variable-Temperature Pulsed Force Mode Atomic Force Microscopy

“…These results reveal a morphology that is far removed from the widely accepted structural model of these materials, having phases an order of magnitude larger than that of individual hard and soft segment domains. − If the results indicate real morphology, then we must be detecting structures, whose growth results from the cooperative behavior of a large number of individual hard or soft domains. If the hard and soft segment domains present at the surface reflect bulk phases, then the nature and size of the individual segmented copolymer molecules dictate that the hard phases must contain a high proportion of soft segment material, and vice versa.…”

“…In the second part of this study, three elastomeric segmented polyurethane (SPU) samples are investigated. Numerous studies have been published on the morphology of such materials, − in which small-angle X-ray scattering (SAXS) and other methods have been used to characterize their phase-separated structure. These typically reveal domain sizes of the order of 5−25 nm.…”

Poly(amide–ether) Thermoplastic Elastomers Based on Monodisperse Aromatic Amide Hard Segments as Shape-Memory and Moisture-Responsive Materials

“…They are commonly applied as gas separation membranes, − reactive multiphase blends, , thermoelectric generator components, conductive materials, , and shape-memory polymers (SMPs) . The properties of TPEs are strongly influenced by the molecular weight distribution ( M w / M n ) of the HS, − but M w / M n cannot be usually controlled for aliphatic polyamides such as nylon-6,6 and nylon-6,10. Furthermore, amide-based HSs generally have hydrogen-bonding sites, making it difficult to prepare specifically desired (particularly longer) HSs because of their poor solubility.…”

Rapid synthesis and properties of segmented block copolymers based on monodisperse aromatic poly(N-methyl benzamide) and poly(propylene oxide)

“…Samuels and Wilkes studied poly(urethane)s using WAXS, where an increasing HS length resulted in higher crystallinity with a thicker lamellar structure. 33 Hydrogen-bondable segmented poly(urethane)s based on 4,4 0 -methylenebis(phenyl isocyanate) (MDI), poly (tetramethylene oxide) (PTMO), and butanediol were then reported by Miller and his co-workers, and found that the polymers having a low M w /M n in the HSs showed a smaller degree of phase mixing, and thus, higher strain in the polymers. 34 Despite the controllable toughness and the elongation ability by choosing an isocyanate molecule as a proper HS unit, the ow temperature of these polymers is typically from 50 to 150 C, and they tend to degrade on heating over the melting temperature.…”