Synthesis and characterization of novel polyurethanes based on 2,6‐bis(4‐hydroxybenzylidene) cyclohexanone hard segments

Abstract

Four novel polyurethanes (PUs) containing 2,6-bis(4-hydroxybenzylidene) cyclohexanone hard segments with four diisocyanate, namely, 4,4 0 -diphenylmethane diisocyanate, toluene 2,4-diisocyanate, isophorone diisocyanate, and hexamethylene diisocyanate, were prepared. Structural elucidation and thermal characterization of these PUs were done by Fourier transform infrared, UV, and fluorescence spectroscopy, 1 H-NMR, 13 C-NMR, and differential thermal analysis/thermogravimetric analysis. All of the PUs contained domains of semicrystalline and amorphous structures as indicated by X-ray diffraction. PUs were soluble in polar aprotic solvents such as N-methyl-2-pyrrolidone, dimethylformamide, and dimethyl sulfoxide. Acoustic properties were calculated from the group contribution method.

Synthesis and characterization of novel polyurethanes based on N1,N4‐bis[(4‐hydroxyphenyl)methylene]succinohydrazide hard segment

“…All the PUs display the amorphous nature, while PU‐2 exhibits semicrystallinity. These results are in good agreement with our previous reports 9, 10, 15–17…”

“…Blackwell and Lee26 studied the multiple melting in MDI‐based PUs that have been oriented and thermally annealed. Recently, Raghu et al9, 10, 15–17 observed 2–5 endothermic transitions associated with the hard segmented PUs and polyureas. In the light of these reports, it is obvious that the melting behavior of PUs is highly dependent upon the procedure adopted for sample preparation.…”

“…To overcome such difficulties, polymer structure modification is necessary, wherein one can introduce asymmetric or bulky groups on the pendant polymer backbone or incorporate noncoplanar structural units on the main polymer chain 11–14. In our previous papers,15–17 Schiff‐based PUs, chalcone‐based PUs and azo‐based diol containing PUs have been prepared using 2,2′‐{ethane‐1,2‐diylbis(nitrilomethylylidene)}diphenol, 2,2′‐{hexane‐1,6‐diylbis(nitrilomethylylidene)} diphenol, 2,2′‐{1,4‐phenylenebis‐[nitrilomethylylidene]}diphenol, 2,2′‐{4,4′‐methylene di‐2‐methylphenylene‐1,1′‐bis[nitrilomethylylidene]}diphenol, 2,6‐bis(4‐hydroxy‐benzylidene)cyclohexanone, 4,4′‐[1,4‐phenylenedi‐diazene‐2,1‐diyl]bis(2‐carboxy‐phenol), and 4,4′‐[1,4‐phenylenedi‐diazene‐2,1‐diyl]bis(2‐chlorophenol) with different diisocyanates.…”

Radiation Crosslinking of Polyurethanes: Characterization by FTIR, TGA, SEM, XRD, and Raman Spectroscopy

“…There are further studies about polyurethane elastomers with graded structure. Raghu and coworkers [2][3][4][5][6] reported the synthesis and characterization of novel linear segmented polyurethanes (PUs) containing Schiff base, (2-carboxyphenol), and 4,4 -[henylenedi-diazene-2,1-diyl]bis(2-chlorophenol) with various diisocyanates [2,3,[7][8][9]. And they successes to introduce a dihydrazide diol moiety in the main chain like N 1 ,N 2 -bis[(4-hydroxyphenyl)methylene]ethanedihydrazide (BHPMED) with 4,4 -diphenylmethane diisocyanate (MDI), tolylene 2,4-diisocyanate (TDI), isophorone diisocyanate (IPDI), and hexamethylene diisocyanate (HDI) [3].…”

Polyamidoamine dendrimers as curing agents: The optimum polyamidoamine concentration selected by dynamic torsional vibration method and thermogravimetric analyses

“…The rigid unit does not have to exhibit liquid crystallinity itself to be used as a mesogenic unit in a LC polymers 10. It must, however, possess an appreciable amount of stiffness, the molecule contain noncoplanar structure units,11 asymmetrical in shape12 and even a complex architectures of polymers 13. Such a novel class of macromolecules with conformational isomerization were provided by dendrimers or hyperbranched14 polymers and tree like architecture15 were displayed liquid crystallinity.…”