Synthesis and structure/properties characterizations of four polyurethane model hard segments

Abstract

Four model polyurethane (PU) hard segments were synthesized by reaction of butanol with four typical diisocyanates. The four diisocyanates were aromatic 4,4′-diphenylmethane diisocyanate (4,4′-MDI) and MDI-50 (50% mixture of 2,4′-MDI and 4,4′-MDI), cycloaliphatic 4,4′-dicyclohexylmethane diisocyanate (HMDI) and linear aliphatic 1,6-hexamethylene diisocyanate (HDI). FTIR, 1H NMR, 13C NMR, MS, X-ray and DSC methods were employed to determine their structures and to analyse their crystallization behaviours and hydrogen bonding interactions. Each of the four PU compounds prepared in the present work displays unique spectral characteristics. The FTIR bands and NMR resonance peaks assigned in the four samples thus provide a reliable database and starting point for investigating the relationship between hard segment structure and the crystallization and hydrogen bonding behaviour in more complex-segmented PU compositions.

Three dimensional polyurethane/ hydroxyapatite bioactive scaffolds: The role of hydroxyapatite on pore generation

“…The FTIR spectra of the samples are shown in Figure 4. The characteristic spectral bands of PU foam are observed at 3536 cm −1 (─O─H stretching) 28,29 , 3401 (free ─N─H stretching in urethane linkage) 17,30 , 3290 cm −1 (hydrogen-bonded ─N─H stretching in urethane linkage) 17,31 , 2800-3000 cm −1 (─CH vibration consisting of asymmetric ─CH 3 stretching at 2972 cm −1 , asymmetric ─CH 2 stretching at 2926 cm −1 , symmetric ─CH 3 stretch at 2872 cm −1 , and symmetric ─CH 2 stretching at 2851 cm −1 in aliphatic structure) 32 , 1729 cm −1 (─C=O stretching in urethane linkage) 26,33,34 , 1603 cm −1 (─C=C─ stretching in aromatic structure) 27 , 1530 cm −1 (─N─CO stretching and ─N − H bending in urethane linkage) 34,35 , 1412 cm −1 (─C─N stretching in primary amide) 35 , 1312 cm −1 (─N − H bending and ─C − N stretching in urethane linkage) 35 and 1223 cm −1 (amide III and ─O─C stretching in urethane linkage) 36,37 and 1071 cm −1 (─O─C stretching in linkage of ether) 28,38 , 1012 cm −1 (─C─N stretching in primary amine and ─O─C stretching), 32,38 respectively. Moreover, absorption bands at 1603, 763 cm −1 , and a broad weak absorption band at 445-495 cm −1 32,39,40 is assigned to primary amine group (─NH 2 ).…”

High‐damping polyurethane/hollow glass microspheres sound insulation materials: Preparation and characterization

“…35 The Amide II is at the region of 1530 cm −1 . 34,36 No NCO stretching peak is observed at 2260 cm −1 , indicating that the reaction of the PUE was completed. 37 The bands at around 1600 cm −1 can be assigned to the vibration absorption peak of the benzene ring, indicating that the PUE has the presence of benzene ring.…”

“…From Figure 3(a), the characteristic peak of N H is confirmed by the peak at 3280 cm −1 . 34 Peaks at 2850 and 2970 cm −1 are ascribed to the asymmetric and symmetric CH 2 stretches. 35 The Amide II is at the region of 1530 cm −1 .…”

Synthesis and molecular interaction of tung oil‐based anionic waterborne polyurethane dispersion

“…In order to further analyze these HTO-APUD structures (including those caused by location of HTO and different diisocyanates) from the perspective of H-bonds, it is necessary to simplify the structure in order to ensure correct assignment for the main FTIR bands. Such model compounds with relatively simple but definite structure (e.g., with only hard segment [27] ) make it possible to better study more complicated segmented polyurethanes by both spectroscopic and simulation methods. [28][29][30] To this end, we synthesized three groups (six samples) of model compounds which relate to HTO-APUD, in this case those synthesized by reacting HTO, DMPA, and PTMG with the two different diisocyanates used in the present study, HMDI and IPDI.…”