Thermal and dynamic mechanical behaviour of calcium containing co-polyurethanes (2023)

Polyurethanes are becoming increasingly important as engineering materials because they have excellent abrasion resistance and the properties of both elastomers and plastics. The growth of science and technology of polyurethanes leads to the development of new materials with more desirable properties. Such kinds of materials include metal-containing polyurethanes, poly(urethane–urea)s and poly(urethane–ether)s with isocyanate structural units combining the properties of enhanced thermal stability, fire retardancy, flexibility and solubility. Ionic diols containing metal salts are used as important starting materials for the synthesis of metal-containing polyurethanes in which the metal is firmly incorporated in the backbone of the polymer chain. Incorporation of metal into polyurethanes has led to wide application as aqueous thickeners, impregnates, textile sizers, adhesives, additives, resins and catalysts. The aim of this work is to present an overview of the various methods of preparation and properties of metal-containing polyurethanes and their copolymers.

Zinc salt of mono(hydroxypentyl)phthalate, Zn(HPP)₂, was synthesized by reacting 1,5-pentanediol, phthalic anhydride and zinc acetate. Zinc-containing poly(urethane-ether)s (PUEs) were synthesized by reacting hexamethylene diisocyanate (HMDI) or toluene 2,4-diisocyanate (TDI) with a mixture of Zn(HPP)₂ and poly(ethylene glycol) (PEG₃₀₀ or PEG₄₀₀) in dimethylsulfoxide (DMSO) at 95°C under nitrogen atmosphere using di-n-butyltin dilaurate as a catalyst. Blank PUEs without Zn(HPP)₂ were also prepared by reacting PEG₃₀₀ or PEG₄₀₀ with HMDI or TDI under similar conditions. The structure of the polymers was confirmed by FT-IR, ¹H NMR, ¹³C NMR, and solid-state ¹³C-CP-MAS NMR spectra. The zinc-containing polymers were soluble in only highly polar solvents. The inherent viscosity of the zinc-containing PUEs was found to be very low. X-ray diffraction studies revealed that HMDI-based (PUEs) were partially crystalline while TDI based (PUEs) were amorphous. The T_g values of the zinc-containing PUEs were found to be low and range from 5.3 to 7.5°C. The thermogravimetric analysis revealed the influence of zinc on the initial decomposition and the overall thermal stability of the polymers.

Journal of Molecular Structure, Volume 1072, 2014, pp. 13-19

In this study, the hydrogen-bonding interactions in one widely used aliphatic hard segment (HS) of shape memory polyurethane, isophorone diisocyanate (IPDI), were investigated theoretically by density functional theory (DFT). The B3LYP/6-31G^* method was used to calculate the equilibrium structures, Mulliken charges, hydrogen-bonding energies, and infrared (IR) spectra, in good agreement with experimental data. Due to chair-structure of cyclohexane ring, a great variety of hydrogen bonds can be formed in IPDI-based HSs. Bond distances R(NH⋯O), which are in the range of 2.894–3.043Å for CO hydrogen bonds, and 3.124Å for ester O hydrogen bond, are in reasonable agreement with experimental values. The charge transfer on atoms N, H and O involved in hydrogen bonding occurs with the forming of hydrogen bond. The CO hydrogen bonding is much stronger than the ester O one. Two hydrogen bonds with one shared carbonyl group are not as strong as two normal hydrogen bonds with two private carbonyl groups. The number of the new absorption peaks in IR spectra is in accordance with the type of hydrogen bonds, which can be well forecasted by the DFT methods with more specific details. Compared with the MDI-based HS, the IPDI-based HSs can form much stronger hydrogen bonds. This study can supply in-depth understanding of the hydrogen-bonding mechanism in the HSs of IPDI-based polyurethane.

Polymer, Volume 55, Issue 16, 2014, pp. 4358-4368

The segmented poly(butylene succinate) urethane ionenes (PBSUI) containing secondary amine cation were synthesized by chain extension reaction of dihydroxyl terminated poly(butylene succinate) and diethanolamine hydrochloride (DEAH) in the presence of hexamethylene diisocyanate. NMR, DSC, WAXD, POM, SAXS, DMA, and rotational rheometer were used to characterize the structure and properties of the PBSUI, and the tensile properties and hydrolytic degradation of the PBSUI were also investigated. All the results suggest that the content of urethane ionic group plays an important role in tuning the properties of the PBSUIs. The crystallization rate increased first and then decreased and the equilibrium melting temperature increased gradually with increasing urethane ionic group content. The maximum crystallization rate was obtained for PBSUI with 3wt% DEAH. The obvious clusters formed by aggregation of urethane ionic group were evidenced by DMA and SAXS for the PBSUI containing 5wt% DEAH. The complex viscosity increased significantly with increasing urethane ionic group content due to the physical crosslinking effect resulted from aggregation of ionic groups. The storage modulus increased with DEAH content increased up to 3wt %, while decreased with further increasing DEAH content. Tensile testing indicated incorporation of urethane ionic group did not change the tensile properties apparently. The hydrolytic degradation rate of the samples increased with the increase in urethane ionic group content which was mainly ascribed to the increased hydrophilicity.

Polymer Testing, Volume 58, 2017, pp. 96-103

The effect of nanoclay fraction on the linear and non-linear tensile properties of a polyethylene/polyamide 12 blend with droplet morphology was investigated. All ternary blends were prepared at a fixed polyamide (PA) weight fraction of 20%, and at clay volume fractions varying from 0.5 to 2.5% relative to PA. Scanning electron microscopy and transmission electron microscopy were used to characterize the morphology of the blends and the clay interphase structure. The nanoclay content was shown to strongly influence both linear and non-linear tensile properties. Young's modulus, elongation at yield, yield strength, tensile strength and elongation at break as a function of clay fraction were studied and discussed in terms of morphological changes and strain-induced structural reorganization of the clay interphase.

Journal of Molecular Structure, Volume 1188, 2019, pp. 129-141

In this review, we explain how pyrazine (hereafter as pz) leds to various structures spanning from multicomponent molecular crystals to coordination polymers. An important factor in the study of pz-based compounds is the crucial roles of the non-covalent interactions; we examined it with pz-based cocrystals and salts and also show that how purposeful selection of ligands with various functional groups can influence the physico-chemical property of the final structures. Furthermore, the CSD analysis revealed that due to the N,N′-exo-bidentate nature of pz, the probability of polymeric compounds are much more than the dimers and monomers counterparts. We also showed that pz-based coordination polymers (CPs) can be categorized into two groups; i) CPs that expanding with only pz ligand into 1D to 3D structures. ii) CPs that are constituted from pz and some auxiliary ligands in which pz linked 2D layers and created porous extended CPs and metal organic frameworks (MOFs). We presented important applications of pz-based compounds in the spin crossover systems. Finally, this review summarized some structural features of pz ligand that are useful for the design and preparation of new materials, serving as a reference in learning more about this particular area which inspired new researchers.

Journal of Molecular Liquids, Volume 296, 2019, Article 111896

1,4-bis(3-(m-aminobenzyl)imidazole-1-yl)butane bis(hexafluorinephosphate), a novel geminal dicationic ionic liquid (GDIL) containing anilino groups has been synthesized to prepare a novel poly-geminal dicationic ionic liquid film by electro-polymerization. The morphology and structure of the PGDIL film were analyzed by SEM and FTIR, and a possible polymerization mechanism of GDIL on an Au electrode surface was determined to be 3D instantaneous nucleation. The existence of polyaniline-like units in the PGDIL chain was confirmed by FTIR, indicating that the anilino groups of GDIL were electro-polymerized on the surface of the Au electrode using the chronoamperometry method. The electrochemical performance of the PGDIL film in phenol was studied by cyclic voltammetry, and it was determined that the PGDIL film electrode promoted enhanced phenol electrocatalysis compared to the untreated Au electrode. This work extends the application range of poly ionic liquids and associates ionic liquids with conductive polymers. Where further studies on other physical and chemical properties of polymers will be necessary.

Journal of Industrial and Engineering Chemistry, Volume 74, 2019, pp. 1-6

A copoly(ionic liquid) (coPIL) based on 1,2,3-triazolium bearing trioxyethylene and tetraoxyethylene spacers was successfully synthesized as electrolyte for all-solid state electrochromic devices (ECD). This polyelectrolyte was produced by reacting triethylene glycol (TEG3)-diazide and tetraethylene glycol (TEG4)-dialkyne monomers through a ‘click’ reaction, copper-catalyzed alkyne-azidecycloadditon (CuAAC), and subsequently underwent several alkylation and anion metathesis. The new coPIL bearing ethylene glycol fragments exhibited excellent thermal degradation temperature (T_d10 = 230 °C) and ionic conductivity (σ = 8.8 × 10⁻⁵ S cm⁻¹) which resulted to an efficient color switching (t_c = 11.8 s and t_b = 6.2 s), a high optical contrast (ΔT = 24%) and a remarkable stability (after 3000 cycles) of a symmetric all-solid-state smart glass window. The structural design of this new polyelectrolyte material and its corresponding properties make it an excellent electrolyte for many electrochemical devices that require zero electrolyte leakage.