Synthesis and characterization of new aromatic polyesters containing pendent naphthyl units

Two bisphenols, viz., 4,4′‐[1‐(2‐naphthalenyl)ethylidene]bisphenol and 4,4′‐[1‐(2‐naphthalenyl) ethylidene]bis‐3‐methylphenol were prepared by condensation of commercially available 2‐acetonaphthanone with phenol and o‐cresol, respectively. A series of new aromatic polyesters containing pendent naphthyl units was synthesized by phase‐transfer‐catalyzed interfacial polycondensation of these bisphenols with isophthaloyl chloride, terephthaloyl chloride, and a mixture of isophthaloyl chloride/terephthaloyl chloride (50 : 50 mol %). Inherent viscosities of polyesters were in the range 0.83–1.76 dL g⁻¹, while number average molecular weights (M_n) were in the range 61,000–235,000 g mol⁻¹. Polyesters were readily soluble in organic solvents such as dichloromethane, chloroform, tetrahydrofuran, m‐cresol, pyridine, N,N‐dimethylformamide, N,N‐dimethylacetamide, and 1‐methyl‐2‐pyrrolidinone at room temperature. Tough, transparent, and flexible films were cast from a solution of polyesters in chloroform. X‐Ray diffraction measurements displayed a broad halo at 2θ ≅ 19° indicating the amorphous nature of polyesters. Glass transition temperatures of polyesters were in the range 209–259°C. The temperature at 10% weight loss (T₁₀), determined by TGA in nitrogen atmosphere, of polyesters was in the range 435–500°C indicating their good thermal stability. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Synthesis and properties of novel star-shaped polyesters based on l-lactide and castor oil

The topology of biodegradable polyesters can be adjusted by incorporating multifunctional polyols into the polyester backbone to obtain branched polymers. The aim of this study was to prepare the biodegradable-branched polyester polyols based on l-lactide and castor oil using the trifluoromethanesulfonic acid as a catalyst. FTIR and ¹H NMR spectroscopy measurements were used to estimate the molecular structure of the novel materials. The polyester polyol was synthesized by ‘‘core-first” method which involves a polymerization of l-lactide by using a castor oil as multifunctional initiator. Molar masses estimated by gel permeation chromatography and vapor pressure osmometry were in good correlation with calculated values based on hydroxyl number of obtained polymers. DSC measurements confirmed high crystallinity degree of the synthesized material. It was assessed that the molar masses of obtained polymers-influenced glass transition temperature significantly. The thermal stability was investigated by TG analysis, and the results have shown the dependence of weight loss on the arm length of the star-shaped polyesters. The thermal stability of star-shaped polyesters significantly decreased with degradation of polyester polyol obtained in acid solution.     

Preparation and characterization of comb-shaped polyesters from 2,2-dioctadecyl-1,3-propanediol and phthalic acids

Summary New types of comb-shaped polyesters have been prepared by transesterification of 2,2-dioctadecyl-1,3-propanediol and the three isomeric diphenyl phthalates. Intrinsic viscosity and SEC analyses allowed determination of DPs (60–89) and molar masses; results compare well with absolute average weight molar masses (56,000–118,000) determined by low-angle laser light scattering. High-resolution ¹³C NMR reveals the characteristic aromatic and glycol polyester patterns; it resolves many side-chain methylene carbons, but shows no evidence of end-groups. All the polyesters are crystalline as shown by X-ray diffractometry and DSC, the crystallinity being exclusively due to the octadecyl side-group crystallization in the hexagonal form. The results indicate that the crystallinity decreases substantially when going from the ortho- to the terephthalate polyester.     

Preparation and performance of poly(ethylene oxide)-based composite solid electrolyte for all solid-state lithium batteries

Poly(ethylene oxide)-based solid electrolyte is attractive for using in all solid-state lithium batteries. However, the polymer has a certain degree of crystallization, which is adverse to the conduction of lithium ions. In order to overcome this drawback, a flexible composite polymer electrolyte (CPE) containing TiO₂ nanoparticles is elaborately designed and synthesized by tape casting method. The effects of different molar ratios of EO: Li and mass fraction of TiO₂ on the physical and electrochemical performances are carefully studied. The results show the CPE10 having 10 wt % TiO₂ has the lowest degree of crystallinity of 9.04%, the lowest activation energy of 8.63 × 10⁻⁵ eV mol⁻¹. Besides, the CPE10 shows a lower polarization and higher decomposition voltage. Thus, prepared all solid-state battery LiFePO₄/CPE10/Li shows a high initial capacity of 160 mAh g⁻¹ at 0.1 C, 134 mAh g⁻¹ at 0.5 C and higher capacity retention of 93.2% after 50 cycles at 0.5 C (1 C = 170 mAh g⁻¹). © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47498.     

Ionic polymers with tunable liquid‐crystalline properties

Side‐chain polyesters were synthesized from N‐octyl‐, N‐dodecyl‐ or N‐hexadecyl‐diethanolamine and succinic acid anhydride. These polyesters were then transformed into polyester hydrochlorides by protonation of the amino groups using different amounts of HCl (20–100 mol%). Above 60 mol% the reaction is not quantitative and a degree of protonation of up to 88% is obtained. The structures of the synthesized polyesters and their hydrochlorides were determined by ¹H nuclear magnetic resonance spectroscopy. The thermal properties of the synthesized polyesters and their hydrochlorides were also studied using differential scanning calorimetry in relation to the side‐chain length and the degree of polyester protonation. The polyester with octyl side chains and its hydrochlorides were amorphous liquids at room temperature, while the polyester and polyester hydrochlorides with hexadecyl side chains formed a smectic crystalline phase, S_mB, or its tilted analogues. The polyester with a dodecyl side chain was also an amorphous liquid at room temperature, while its hydrochlorides with various degrees of protonation were smectic liquid crystals, as determined by X‐ray diffraction. By simply varying the degree of protonation the liquid crystal isotropization temperature was increased from 32 °C to 82 °C. Copyright © 2011 Society of Chemical Industry     

Phase morphology of functionalized polyester polyurethanes. Effect of functional group concentration

Segmented polyester polyurethanes (PU) were prepared based on polycaprolactone as a soft segment and a hard segment containing isophoronediisocyanate and chain extenders 2,2′‐bis‐(hydroxymethyl) propionic acid and 1,4‐butanediol with different molar ratios. The changes of crystallinity and morphology due to the incorporation of carboxylic functional groups in the hard segment were monitored by wide‐angle X‐ray diffraction, optical microscopy and differential scanning calorimetry. The concentration of functional groups varied from 0 to 0.45 mmol g⁻¹. The phase separation, the degree of crystallinity and the size of spherulites depend on the interactions imposed by functional groups. A critical level of the concentration of functional groups (0.25 mmol g⁻¹) at which the crystallizability reaches its maximum was observed. Copyright © 2005 Society of Chemical Industry     

Synthesis and enzymatic degradation of high molecular weight aliphatic polyesters

The aliphatic polyesters with high molecular weight have been prepared according to two methods. First is the synthesis of the polyesters by polycondensation of dimethyl succinate (DMS) with 1,4‐butanediol (BD) using various metal alkoxides as a catalyst. Among the metal alkoxides used, titanium tetraisopropoxide [Ti(OiPr)₄] gave the best results (highest molecular weight and yield). Thus, we have prepared aliphatic polyesters using a variety combinations of diesters [MeOOC—(CH₂)_x—COOMe, x = 2–8] with BD by the catalysis of Ti(OiPr)₄. The polyesters with high number‐average molecular weight (M_n > 35,000), except dimethyl adipate (DMA, x = 4)/BD polyester (M_n = 26,900), were obtained in high yield. The melting temperatures (T_m) of polyesters were relatively low (43.4–66.8°C) except that (115.6°C) of the DMS/BD polyester. Second is the synthesis of high molecular weight polyesters by chain extension reaction of lower molecular weight (M_n = 15,900–26,000) polyesters using hexamethylene diisocyanate (HDI) as a chain extender. The M_n values of chain‐extended polyesters consequently increased more than two times (M_n = 34,700–56,000). The thermal properties of polyesters hardly changed before and after chain extension. Enzymatic degradations of the polyesters were performed using three different enzymes (cholesterol esterase, lipase B, and Rhizopus delemar lipase) before chain extension. The enzymatic degradability varied depending on both thermal properties of polyesters [melting temperature and heat of fusion (crystallinity)] and the substrate specificity of enzymes, but it was the following order: cholesterol esterase > lipase B > R. delemar lipase. The ¹H‐NMR spectrum of water‐soluble degraded products of the polyester indicated that the polyester was degraded into a condensation product of diol with diester in a monomer form. The enzymatic degradation of chain extended polyesters was slightly smaller than that before chain extension, but proceeded steadily. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 340–347, 2001     

Preparation of waterborne elastic polyesters by chain extension with isophorone diisocyanate as a chain extender

Isophorone diisocyanate was used as a chain extender to coupling the soft segment water-borne polyester with the hard segment water-borne polyester, to overcome the disadvantages of low molar mass and poor mechanical properties of waterborne sulfonate-containing polyesters. The molecular structure of the extended polyester was confirmed by FTIR and ¹H NMR, and the increased molar mass of the resultant was characterized by SEC. The extended products could be dispersed in water with the emulsion particle size less than 50 nm in diameter, slightly larger than that of precursors of soft- and hard-segment polyesters. The emulsion viscosity of polyesters after the chain extension was lower when the emulsion concentration was not larger than 25 wt%, which is conducive to the spraying application of the polyester for coating. DSC analysis indicated that the polyester after chain extension had two different glass temperatures, suggesting that the polyester bulk had a microphase separation structure. The mechanical performance of the coupled polyester manifested an obviously improved elongation at break and had a feature of higher elastic recovery rate. The results of this study indicate that the chain extension is an effective method to increase the molar mass and improve mechanical properties of waterborne polyesters. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48453.     

Solubility of potassium ferrate in 12 M alkaline solutions between 20°C and 60°C

The solubility of potassium ferrate (K₂FeO₄) was measured in aqueous solutions of NaOH and KOH of total concentration 12 M containing various molar ratios of KOH:NaOH in the range 12:0 to 3:9. Several analytical methods were tested for the determination of ferrate concentration. The final method chosen consisted of potentiometric titration of the ferrate sample with an alkaline solution of As₂O₃. The assumption was made that ferrate dissociates in concentrated KOH solutions predominantly to KFeO₄⁻. The solubility constant, S, defined as the product of the molar concentration of the potassium ion, K⁺, and the ferrate anion, KFeO₄⁻, was found to be 0·044 ± 0·006 mol² dm⁻⁶ for 20°C, 0·093 ± 0·004 mol² dm⁻⁶ for 40°C and 0·15 ± 0·09 mol² dm⁻⁶ for 60°C. From these results the heat of dissolution of K₂FeO₄ was calculated as −14·3 kJ mol⁻¹. At 60°C the enhanced decomposition of the ferrate at the higher temperature led to a greater deviation in solubility values compared with data for either 20°C or 40°C.     

Preparation of an acrylics‐grafted polyester and its aqueous dispersion—Structural study of acrylics‐grafted polyesters

Structural study of two grafted polyesters, which were different in mechanical properties, was investigated by DMA, TEM, and high‐resolution solid‐state ¹³C‐NMR. Using DMA and TEM, a separated phase larger than 100 nm was not found in the grafted polyesters. The main chain and the side chain seemed miscible. Analysis of T_1ρHs and their distributions made the difference of microstructure in the grafted polyesters clear. P(EA‐AA)‐grafted polyester, which was very brittle, had a separated phase in the grafted polyester. The separated phase was estimated to be at a size of about 3 nm. On the other hand, P(St‐DEF‐MAnh)‐grafted polyester, which was very ductile, had a homogeneous microstructure. The difference in the microstructures of the grafted polyesters seemed to effect the mechanical properties of the grafted polyesters. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 392–402, 2000     

Synthesis and Kinetic Studies on Dimer Fatty Acid/Polyethylene Glycol Polyester

Dimer fatty acid polyethylene glycol polyester, a new kind of non-ionic polymeric surfactant, was synthesized by using dimer fatty acid and polyethylene glycol (400) as materials in this paper. The optimum reaction conditions of esterification were as follows: the molar ratio of dimer fatty acid (DFA)/PEG (400) is 1 / 1.20, the preferable catalyst is stannous chloride and the amount is 0.3% (w/w) of the mass of DFA, reaction temperature is 200°C, reaction time is 6 h. The conversion ratio of polyesterification can reach 98.11%. A new kinetic model of polyesterification reaction catalyzed with stannous chloride was presented. The Genetic Algorithms and Runge–Kutta were used to estimate the parameters of the kinetic model. The results of experiments and computer operations indicated that the reaction order is 0.998 to the carboxyl and 1 order to the hydroxyl. The activation energy obtained from Arrhenius plot is 97.18 kJ mol⁻¹, and the pre-exponential frequency factor is lnA = 21.39 kg² mol⁻² min⁻¹ at temperature range of 160 ∼ 190°C.     

Sugar-based bicyclic monomers for aliphatic polyesters: a comparative appraisal of acetalized alditols and isosorbide

Three series of polyalkanoates (adipates, suberates and sebacates) were synthesized using as monomers three sugar-based bicyclic diols derived from D-glucose (Glux-diol and isosorbide) and D-mannose (Manx-diol). Polycondensations were conducted in the melt applying similar reaction conditions for all cases. The aim was to compare the three bicyclic diols regarding their suitability to render aliphatic polyesters with enhanced thermal and mechanical properties. The ensuing polyesters had molecular weights (M_w) in the 25,000–50,000 g mol^?1 range with highest values being attained for Glux-diol. All the polyesters started to decompose above 300 °C and most of them did not display perceivable crystallinity. On the contrary, they had glass transition temperatures much higher than usually found in homologous polyesters made of alkanediols, and showed a stress–strain behavior consistent with their T_g values. Glux-diol was particularly effective in increasing the T_g and to render therefore polyesters with high elastic modulus and considerable mechanical strength.     

Glycerol Partial Oxidation over Pt/Al2O3 Catalysts under Basic and Base-Free Conditions—Effect of the Particle Size

The glycerol partial oxidation reaction over Pt/Al₂O₃ catalysts was studied under basic (NaOH/GLY molar ratio 4) and base-free conditions (NaOH/GLY molar ratio 0). Catalysts with small (2.95 nm) and large particle sizes (260.83 nm) were synthesized according to the use of different reducing agents, formaldehyde or sodium borohydride, and hydrazine, respectively. These different Pt particle sizes lead to a dramatic change in terms of activity, irrespective of the applied conditions. The biggest particles (i.e., 260 nm) seem to generate overoxidation products leading to a decrease in the carbon balance (to ~80%) while the smallest particles exhibit the highest initial glycerol transformation rate (i.e., ~10,000 mol h⁻¹ mol_Pt⁻¹ under basic conditions at 60°C and ~2000 mol h⁻¹ mol_Pt⁻¹ in the absence of a base at 100°C). In terms of selectivities, the main products are different as a function of the initial reaction conditions. For base-free conditions, the two main products are glyceraldehyde and glyceric acid with a sum of selectivities always larger than 80%. Under basic conditions, the major product is glyceric acid while no trace of glyceraldehyde is detected.     

Synthesis and characterization of unsaturated polyester/carborundum composites

Two unsaturated polyesters, one based on phthalic anhydride PE_P and the other based on isophthalic acid PE_I, were synthesized. The chemical structure of the two polyesters was characterized by IR and ¹H and ¹³C NMR spectroscopy. The effect of styrene concentration on the curing of polyesters was also studied. It has been found that the percent of polyester/styrene (70/30 wt %) gave the highest percent of curing. Different concentrations of carborundum (0–70 wt %) were used to prepare polyester composites. A comparative study was done on the properties of the two prepared polyesters PE_P and PE_I and their composites in term of their thermal, mechanical, electrical, and physical properties. The results indicate that the polyester based on isophthalic acid (PE_I) and its composites gave higher compressive strength values and lower water absorption than those based on phthalic anhydride (PE_P). The presence of carborundum improved the thermal stability than the cured polyesters and electrical properties. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Synthesis of Water-Soluble Polyesters Containing Carboxy-Functional Groups in the Polymers Chain and Study of Their Metal Complexes

The diethylenetriaminepentaacetic acid bisanhydride (DTPABA) was synthesized from diethylenetriaminepentaacetic acid (DTPA) and was further subjected to polyaddition with diols like polyethylene glycols (PEG) of different molar masses to form the polyesters. The polyesters synthesized were soluble in water as well as organic solvents and show better complexing ability than their monomer. The metal complexes of polyesters were synthesized by the reaction of water-soluble polyesters with copper acetate. The synthesized water-soluble polyester and their copper complexes were characterized by their melting points, elemental analysis, UV–Vis spectroscopy, viscometry, FTIR, ¹H NMR, SEM, AFM, XRD data, thermal stability of the compounds synthesized was studied by TG-DTA analysis. The antibacterial activity of synthesized polyesters has been studied against the bacterial species Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa and Bacillus subtilis.     

Synthesis and characterization of new fluorinated aromatic polyesters containing trifluoromethylphenoxy pendant groups

A series of novel fluorinated aromatic polyesters containing trifluoromethylphenoxy pendant groups was synthesized by interfacial polycondensation of 2‐(4‐trifluoromethylphenoxy)terephthalyl chloride with various bisphenols in dichloromethane. The polyesters obtained in good yields had weight‐average molecular weights of 70,600–29,800 g/mol, polydispersities of 1.81–2.08, and were all amorphous. All polyesters were easily soluble in organic solvents such as N,N‐dimethylformamide, tetrahydrofuran, o‐chlorophenol, pyridine, and dichloromethane. These fluorinated polyesters showed glass transition temperature of 133–210°C, and good thermal stability with almost no weight loss up to 378°C, the 10% weight loss temperature of 472–523°C as well as char yield of 32–63% at 600°C in nitrogen. These polyester films cast from chloroform solutions exhibited tensile strengths ranging from 102 to 126 MPa, elongation at break from 6.3% to 11.7%, and tensile moduli from 2.1 to 3.3 GPa. The resulting polyester films also displayed low dielectric constants between 2.18 and 2.49 (1 MHz), high transparency with an ultraviolet‐visible absorption cut‐off wavelengths in the 332–355 nm range, and excellent electric strengths (50.4–65.6 kV/mm) and volume resistivity (2.51–6.03 × 10¹⁶ Ω cm). © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Kinetic and rheokinetic study of dicarboxylic fatty acid chain extension using a dioxazoline coupling agent

A kinetic and rheokinetic study of the condensation reaction of a dicarboxylic fatty acid, Pripol®1009 (C36), and a dioxazoline coupling agent (1,3‐Phenylene)‐bis(2‐Oxazoline) (OO) was made. The kinetic study showed a similar reactivity of the two acid groups of C36 and also a similar reactivity of the two oxazoline groups of OO. The reaction kinetics can be described using a second‐order kinetic model. A kinetic constant k = 16.1 × 10⁻⁴ mol⁻¹ s⁻¹ at 156°C with an activation energy E_a = 80.6 kJ mol⁻¹ was calculated. A rheological evaluation of the reactants and the obtained polymers showed that the reactive system had Newtonian behavior during all the reaction times for shear rates lower than 100 s⁻¹. Using this kinetic modeling and measured viscosity evolution of the reactive system at different temperatures, rheokinetic models were proposed for viscosity evolution with the molar mass evolution of the synthesized polymer and the reaction time and conversion. Viscosity evolution of the reactive system during the first 10 min, corresponding to a typical mean residence time in reactive extrusion, were calculated using the proposed rheokinetic model. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 1017–1024, 1999     

High‐Pressure Vibrational Spectroscopy of Hexahydro‐ 1,3,5‐Trinitro‐1,3,5‐Triazine (RDX)

The molecular‐level response of RDX to hydrostatic compression was examined in a diamond anvil cell using Raman spectroscopy. The pressure‐induced alterations in spectral profiles of the C N stretching mode (886 cm⁻¹) were studied up to 8.3 GPa. At pressures near 4.4 GPa, several changes of the C N stretching mode become immediately apparent in Raman spectrum, such as large frequency shifts, line broadening, mode splitting, and intensity changes, which are associated with the α–γ phase transition and rearrangement between the RDX molecules. The high pressure Raman spectra changes of the C N stretching mode are indicative of an α–γ phase transition, and also suggest the lowering of molecular symmetry and crystal symmetry, which are expected to provide some insight into RDX molecular stability and decomposition.     

Influence of backbone rigidity on the curing and the dielectric relaxations of unsaturated polyesters

Unsaturated polyesters with maleic acid and different molar ratio of phthalic anhydride to adipic acid were produced, mixed with styrene, and cured. The degree of double bonds conversion, determined by differential scanning calorimetry (α_DSC), indicating the initial curing, increases significantly with the molar ratio of phthalic anhydride. On the other hand, the degree of double bonds conversion of maleate (α_UP,FTIR) and styrene (α_St,FTIR) units determined by Fourier transform infrared spectroscopy after prolonged curing are considerably higher than α_DSC and increase slightly with the molar ratio of phthalic anhydride. Polyester containing phthalic anhydride without adipic acid (M5P5) has the lowest tetrahydrofuran uptake and diffusion parameter D/α² due to its more rigid segments, in opposite to polyester containing adipic acid (M5A5) having the highest values. According to dielectric spectroscopy measurements, two different relaxations were determined, one beginning above 130°C (with peak above 180°C) attributed to α‐relaxation (dielectric glass transition) and a second one at lower temperatures, attributed to β‐relaxation. The peak of β‐relaxation is at around 130, 75–80, and 30°C for the rigid, intermediate rigidity/flexibility, and flexible polyesters, respectively. The α‐relaxation is determined at low frequencies and the β‐relaxation at intermediate or high frequencies. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Raman spectroscopic studies of the polyacrylonitrile-zinc complexes in aqueous solutions of zinc chloride and bromide

Raman spectroscopic studies of the dissolution of polyacrylonitrile (PAN) in aqueous zinc halides are reported. The dissociation constants of aqueous PAN-zinc chloride and PAN-zinc bromide containing 60-75% wt/wt and 65-80% wt/wt zinc in aqueous polyacrylonitrile solutions, respectively, have been measured by Raman spectroscopy. Intensity measurements allowed for a quantitative measurement of the amount of free and complexed CN groups to be made, utilising the 2259 and 2290cm^?1 v(CN) stretching Raman bands. The degree of complexation was found to be small in many of the solutions. The effect of the addition of salt on the structure of the v(OH) band at 3000-3800 cm^?1 was studied for the aqueous zinc salts and an aqueous sodium thiocyanate solution. The low wavenumber regions of the Raman spectra, Δv = 100-350cm^?1, for both zinc chloride and zinc bromide solutions of PAN have also been studied.