Synthesis and hydrolysis of β-cyanoethyl ether of poly(vinyl alcohol)

Poly(vinyl alcohol) (PVA) was cyanoethylated by reaction with acrylonitrile in the presence of sodium hydroxide and quaternary ammonium halide. Quaternary ammonium halide, acting as a phase transfer catalyst, increases the degree of substitution (DS) of PVA. The DS also increased with increasing acrylonitrile concentration. Cyanoethylation of PVA up to 98% can be achieved under optimum conditions. The hydrolysis of β-cyanoethyl ether of PVA (CN–PVA) was studied. The rate of hydrolysis was affected by the sodium hydroxide concentration and the reaction temperature. The rheological properties of aqueous solution of hydrolysis product of CN–PVA were determined at different temperatures, and the flow activation energy was calculated. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 2771–2777, 1999     

Organosoluble and colorless fluorinated poly(ether imide)s derived from a highly contorted biphenyl-2,2′-diol bis(ether anhydride) and aromatic bis(ether amine)s with trifluoromethyl substituents

A series of new fluorinated aromatic poly(ether imide)s (PEIs) were prepared from highly contorted 2,2′-bis(3,4-dicarboxyphenoxy)biphenyl dianhydride and various trifluoromethyl-containing bis(ether amine)s via chemical or thermal imidization. All the PEIs showed good solubility in a variety of organic solvents and could afford flexible, colorless, and transparent thin films via solution-casting. They showed cut-off wavelengths of Uv-vis absorptions below 380 nm and very low yellowness index (b* < 7.0). They also showed high thermal stability with the 10% weight loss temperature from 503 to 585 °C of in nitrogen or air atmosphere. The glass transition temperatures (T _gs) are recorded in the range of 194–254 °C by DSC. For a comparative study, another series of non-fluorinated PEIs derived from the same biphenyl-2,2′-diol bis(ether anhydride) with various bis(ether amine)s without the trifluoromethyl substituents were also synthesized and characterized.     

Synthesis and characterization of poly(11-(4′-cyano-trans-4-stilbenyloxy)undecanyl vinyl ether)

Summary Polymers based on 11-(4-cyano-trans-4-stilbenyloxy)undecanyl vinyl ether have been synthesized by living cationic polymerization, photo-initiated cationic polymerization using onium salts and thermal initiated cationic polymerization using onium salts. The polymers have been characterized by size exclusion chromatography, nuclear magnetic resonance spectroscopy, differential scanning calorimetry and polarized light microscopy. Living cationic polymerization resulted in a polymer of low molecular mass M_n3 600, with a uniformity index (D) of 1.2 displaying a focal conic texture indicative of smectic A (s_A) phase with preserved cyanogroup and trans-configuration. Photo-initiation using 2,4,6-trimethylbenzoylethoxyphenylphosphine oxide and diphenyliodonium hexafluorophosphate resulted in an insoluble polymer exhibiting only vague liquid crystalline textures. Initiation with phenothiazine and phenacyltetramethylenesulfonium hexafluoroantimonate also yielded a partly insoluble polymer with a disturbed s_A phase. It is suggested that the monomer and polymer are sensitive towards radicals leading to cross-linking and branching. The thermal initiation on systems with -methylbenzyltetramethylenesulfonium hexafluorophosphate and p-methoxybenzyltetramethylenesulfonium hexafluorophosphate resulted in completely soluble mesomorphic polymers of M_n13 000, D=1.7 and M_n26 000, D=2.8 respectively, in both cases with a preserved cyanogroup and a transconfiguration. Polarized light microscopy revealed a distinct focal conic structure indicative of s_A in both cases.     

High performance moisture cured poly(ether–urethane) amide coatings based on renewable resource (cottonseed oil)

In this investigation, polyetheramide resin was prepared through the condensation polymerization of N,N-bis (2-hydroxyethyl) cottonseed oil fatty amide (HECOFA) with bisphenol-A. It was further modified by 2,4-toluene diisocyanate (TDI) in 10–30 wt% of polyetheramide to develop a series of moisture curing urethane-modified polyetheramide resins (UMCOPEtA). The synthesized resin was characterized using ¹H NMR, ¹³C NMR, FTIR and solubility in various organic solvents at room temperature. The thermal and curing behavior of the resin was investigated using thermogravimetric analysis and differential scanning calorimetric techniques. The physico-chemical properties such as hydroxyl value, iodine value, specific gravity and mechanical properties like scratch hardness, impact, and flexibility were determined by standard laboratory methods. Coatings of UMCOPEtA resin were prepared on mild steel panels to evaluate chemical resistance performance against acid, alkali, water and xylene. The newly developed UMCOPEtA coatings showed improved hardness, impact, gloss, water and chemical resistance when compared with unmodified polyetheramide coatings, and thus were found to be suitable as a high performance coating material.     

Synthesis and characterization of soluble aromatic poly(ether amide amide ether ketone ketone)s by electrophilic Friedel–Crafts solution polycondensation

A new monomer, N,N′-bis(4-phenoxybenzoyl)-m-phenylenediamine (BPBMPD), was prepared by condensation of m-phenylenediamine with 4-phenoxybenzoyl chloride in N,N-dimethylacetamide (DMAc). Novel soluble aromatic poly(ether amide amide ether ketone ketone)s (PEAAEKKs) were synthesized by electrophilic Friedel–Crafts solution copolycondensation of BPBMPD with a mixture of terephthaloyl chloride (TPC) and isophthaloyl chloride (IPC) in the presence of anhydrous aluminum chloride and N-methylpyrrolidone (NMP) in 1,2-dichloroethane (DCE). The influences of reaction conditions on the preparation of polymers were examined. The polymers obtained were characterized by different physico-chemical techniques such as FT-IR, DSC, TGA, and wide-angle X-ray diffraction (WAXD). All the polymers were amorphous and the solubility of the polymers was improved by the incorporation of 1,3-dibenzoylaminobenzene moieties in the main chain. Thermal analyses showed that the polymers had high T_gs of 220–231 °C and exhibited high thermal stability. All the polymers formed transparent, strong, and flexible films, with tensile strengths of 102.9–108.5 MPa, Young’s moduli of 2.44–2.86 GPa, and elongations at break of 9.8–13.7%.     

Sulfonated poly(ether ether ketone)/s–TiO2 composite membrane for a vanadium redox flow battery

The SPEEK/s-TiO₂ composite membrane was prepared by blending sulfonated poly(ether ether ketone) (SPEEK) and sulfonated titanium dioxide (s-TiO₂) nanoparticles. The important physiochemical parameters such as proton conductivity, water uptake, swelling degree and ion exchange capacity of the composite membrane were measured. The thermal stability and chemical stability were also tested. It was observed that the SPEEK/s-TiO₂ composite membrane exhibited the best selectivity (7.13 × 10⁴ S·min·cm⁻³) accompanying high proton conductivity (0.061 S·cm⁻¹) and low tetravalent vanadium ion (VO²⁺) permeability (8.55 × 10⁻⁷ cm²·min⁻¹) compared with Nafion117, SPEEK and SPEEK/TiO₂ membranes. The battery performance with these membranes was characterized by charge–discharge cycling tests and it was found that the SPEEK/s-TiO₂ composite membrane showed the highest energy efficiency (EE) up to 82.3%, indicating the SPEEK/s-TiO₂ composite membrane is a candidate for vanadium redox flow battery (VRFB) application. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48830.     

Rheological properties of poly(ε-caprolactone) and poly(styrene-co-acrylonitrile) blends

Summary Rheological properties of poly(-caprolactone) (PCL) and Poly (styrene-co-acrylonitrile) (SAN) blends were examined as a function of the acrylonitrile (AN) content in SAN, to systematically understand the correlation between the interaction parameter and the theological properties of miscible polymer blends. When the plateau modulus (G _N ⁰) and zero shear viscosity ( ₀) of the PCL/SAN blends are plotted against the AN content in SAN, a minimum is observed. Qualitatively, the results obtained parallel the variation of the interchain interaction with the AN content. The negative deviation ofG _N ⁰ and ₀ from linearity seems to be attributed to the increase in the entanglement molecular weight between dissimilar chains which results from the chain extension caused by interchain interaction.     

Modified poly(ether–imide–amide)s with pendent benzazole structures: Synthesis and characterization

Three series of novel modified poly(ether–imide–amide)s (PEIAs) having pendent benzazole units were prepared from diimide–dicarboxylic acids, including 2-[3,5-bis(4-trimellitimidophenoxy) phenyl]benzimidazole, 2-[3,5-bis(4-trimellitimidophenoxy) phenyl]benzoxazole, and 2-[3,5-bis(4-trimellitimidophenoxy) phenyl]benzothiazole, with various diamines by direct polycondensation in N-methyl-2-pyrrolidone with triphenyl phosphite and pyridine as condensing agents. These new diimide–dicarboxylic acids containing ether linkages and benzazole pendent groups were synthesized by the condensation reaction of 5-(2-benzimidazole)-1,3-bis(4-aminophenoxy)benzene, 5-(2-benzoxazole)-1,3-bis(4-aminophenoxy)benzene, or 5-(2-benzothiazole)-1,3-bis(4-aminophenoxy)benzene with trimellitic anhydride, respectively. All of the polymers were obtained in quantitative yields with inherent viscosities of 0.39–0.65 dL/g. For comparative purposes, the corresponding unsubstituted PEIAs were also prepared by the reaction of a diimide–dicarboxylic acid monomer lacking benzazole pendent groups, namely, 3,5-bis(4-trimellitimidophenoxy) phenyl, with the same diamines under similar conditions. The solubilities of the modified PEIAs in common organic solvents and their thermal stability were enhanced compared to those of the corresponding unmodified PEIAs. The glass-transition temperature, 10% weight loss temperature, and char yields at 800°C were 19–31°C, 22–57°C and 4–8% higher, respectively, than those of the unmodified polymers. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Nanosized micelles self-assembled from amphiphilic poly(citric acid)–poly(ε-caprolactone)–poly(citric acid) copolymers

In this study, novel ABA-type amphiphilic copolymers consisting of poly(citric acid) (PCA) (A) as hydrophilic segment and poly(ε-caprolactone) (PCL) (B) as hydrophobic block were prepared by an approach in the following two steps: (1) ring-opening polymerization (ROP) of ε-caprolactone with 1,5-pentanediol initiator to obtain a hydroxyl telechelic PCL; (2) melt polycondensation reaction of hydroxyl telechelic PCL and citric acid molecules. The prepared copolymers are capable of self-assembling into nanosized micelles in aqueous solution. The influence of the copolymer composition on the micelle dimensions was investigated. The critical micellar concentration of the copolymers is in the range of 5–6.3 × 10^?2 mg/mL which is determined by the fluorescence probe technique using pyrene. Also the results indicate that CMC of self assembled micelles is influenced by the hydrophilicity of PCA–PCL–PCA copolymers depending on the CA/CP ratio, and these micelles may find great potential as drug carriers in biomedical fields.     

Miscibility of poly(styrene-co-vinyl phenol) with poly(ɛ-caprolactone)

Summary Poly(styrene-co-vinyl phenol) (STVPh)/poly(-caprolactone)(PCL) blends showed enhanced miscibility over polystyrene/PCL blend, and showed single glass transition temperature when the contents of vinyl phenol (VPh) in copolymer were higher than 10 wt % (maximum content of VPh in STVPh used in this study was 20 wt%). STVPh 4, STVPh 7, STVPh 10 (4, 7, 10 were VPh wt%)/PCL blends showed cloud points on heating for miscible blend system, and this phase separation was reversible on cooling. From melting point depression of PCL, interaction parameter, B. for miscible STVPh 12/PCL blend system was evaluated.     

DSC studies of poly(vinyl chloride)/poly(ε-caprolactone)/poly(ε-caprolactone)-b-poly(dimethylsiloxane) blends

Poly(vinyl chloride)/poly(ε-caprolactone)/poly(ε-caprolactone)-b-poly(dimethylsiloxane) [PVC/PCL/(PCL-b-PDMS)] blends were prepared by solvent casting from tetrahydrofuran. The content of PVC was kept constant (60 wt%); the PCL and PCL-b-PDMS contents were varied by replacing different amounts of PCL [0–20 wt% from the PVC/PCL (60/40) blend] with PCL-b-PDMS copolymer having different molecular weights of the PCL blocks. The thermal properties of prepared blends were investigated by differential scanning calorimetry in order to analyse miscibility (through glass transition temperature) and crystallinity. Differential scanning calorimetry analyses show that the PVC/PCL/PCL-b-PDMS blends are multi-phase materials which contain a PVC plasticized with PCL phase, a block copolymer PCL-b-PDMS phase (with crystalline and amorphous PCL and PDMS domains) and a PCL phase (preponderantly crystalline).     

Crystallization and morphology of poly(ethylene succinate) and poly(β-hydroxybutyrate) blends

Summary The melting and crystallization behavior of poly(β-hydroxybutyrate) (PHB) and poly(ethylene succinate) blends has been studied by differential scanning calorimetry and optical microscopy. The results indicate that PHB and PES are miscible in the melt. Consequently the blend exhibits a depression of the melting temperature of both PHB and PES. In addition, a depression of the equilibrium melting temperature of PHB is observed. The Flory-Huggins interaction parameter (χ₁₂ ), obtained from melting point depression data, is composition dependent, and its value is always negative. Isothermal crystallization in the miscible blend system PES/PHB is examined by polarized optical microscope. The presence of the PES component gives a wide variety of morphologies. The spherulites exhibit a banded structure and the band spacing decreases with increase PES content. Received: 29 June 1998/Revised version: 31 August 1998/Accepted: 10 September 1998     

Single-component poly(ε-caprolactone) composites

Non-covalently bonded crystalline inclusion compounds (ICs) have been formed by threading host cyclic starches, α-cyclodextrins (α-CDs), onto guest poly(ε-caprolactone) (PCL) chains and by co-crystallization of guest PCL and host urea (U). PCLs were coalesced from both ICs by appropriate removal of the α-CD and U hosts. When added at low concentrations, PCL coalesced from its α-CD–IC served as an effective self-nucleating agent for the bulk crystallization of as-received PCL from the melt. Film sandwiches consisting of two layers of as-received (asr) (control), and one layer each of asr and self-nucleated (nuc) (composite) PCLs were produced by melt pressing. A composite sandwich consisting of a film of neat PCL coalesced from its U–IC (c-PCL) and a film of asr-PCL was also melt pressed. DSC showed that both composite films maintain their characteristic structures and properties even after melt-pressing them together. Both single component film sandwiches exhibited strong interfaces and better mechanical properties than the asr-PCL/asr-PCL control composite sandwiches. These results are similar to those previously obtained on similarly prepared nylon-6 (N-6) sandwich composites made with asr- and nuc-N-6 films with the same levels of crystallinity. However, while the elongation at break was greatly reduced in the asr-N-6/nuc-N-6 composite, asr-/asr-, asr-/c-, and asr-/nuc-, PCL/PCL-composites all showed similarly large elongations at break. The above room temperature and well below room temperature glass-transition temperatures of N-6 and PCL are likely the cause of their widely different elongations at break.     

Mechanism of thermal generation of poly(p-phenylene vinylene) from poly(p-xylene-α-dimethylsulphonium halides)

The thermal conversion of poly(p-xylene-α-dimethylsulphonium halides) into poly(p-phenylene vinylene) (PPV) can occur through two concomitant reactions. The principal reaction is an elimination of dimethyl sulphide and halogen acid, while the second reaction, an undesirable one, is the nucleophilic attack of the halide counterion on a methyl group to form the methyl halide and a methyl sulphide. The two thermal processes were observed in the pyrolysis of both poly(p-xylene-α-dimethylsulphonium bromide) and poly(p-xylene-α-dimethylsulphonium chloride). On storage at room temperature, poly(p-xylene-α-dimethylsulphonium halides) undergo partial decomposition to PPV, as shown by thermogravimetric experiments. The flash pyrolysis-gas chromatography-mass spectrometry of PPV obtained by the thermal conversion of poly(p-xylene-α-dimethylsulphonium bromide) at 400°C was also investigated.     

Fabrication and cell morphology of a microcellular poly(ether imide)–carbon nanotube composite foam with a three-dimensional shape

The preparation of microcellular poly(ether imide) (PEI) based foams with three-dimensional geometry remains a great challenge worldwide. In this study, we fabricated microcellular PEI–carbon nanotube (CNT) bead foams with a batch rapid depressurization method in a self-designed mold with supercritical carbon dioxide (scCO₂) as a blowing agent. The effects of the saturation time, foaming temperature, foaming pressure, and depressurization rate on the microcellular structures of the PEI foam were analyzed by the Taguchi approach to determine the optimum foaming conditions, and the influence of the CNT content on the cell structure was analyzed. The results show that the depressurization rate and foaming temperature were the key factors influencing the cell size and cell density (N _f); that is, the high depressurization rate and low foaming temperature favored a small cell size and high N _f. The foaming temperature also influenced the foaming ratio (ϕ), and a high ϕ was obtained at a high foaming temperature. Under optimal foaming conditions, PEI with 2.0 wt % CNTs presented the best cell structure; N _f, cell size, and ϕ were 6.14 × 10¹⁰ cell/cm³, 2.43 μm, and 2.08, respectively. The mechanical properties of the final parts were related more to the foaming time and CNT concentration, and the maximum tensile and compression strength were reached at 3 h foaming time and 2.0 wt % CNT, that is, at 2.75 and 15.1 MPa (10% strain), respectively. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47501.     

Effect of poly(ε-caprolactone) and titanium (IV) dioxide content on the UV and hydrolytic degradation of poly(lactic acid)/poly(ε-caprolactone) blends

The effect of accelerated weathering degradation on the properties of poly(lactic acid) (PLA)/poly(ε-caprolactone) (PCL) blends and PLA/PCL/titanium (IV) dioxide (TiO₂) nanocomposites are presented in this paper. The results show that both polymers are susceptible to weathering degradation, but their degradation rates are different and are also influenced by the presence of TiO₂ in the samples. Visual, microscopic and atomic force microsocpy observations of the surface after accelerated weathering tests confirmed that degradation occurred faster in the PLA/PCL blends than in the PLA/PCL/TiO₂ nanocomposites. The X-ray diffraction results showed the degradation of PCL in the disappearance of its characteristic peaks over weathering time, and also confirmed that PLA lost its amorphous character and developed crystals from the shorter chains formed as a result of degradative chain scission. It was further observed that the presence of TiO₂ retarded the degradation of both PLA and PCL. These results were supported by the differential scanning calorimetry results. The thermogravimetric analysis results confirmed that that PLA and PCL respectively influenced each other's thermal degradation, and that TiO₂ played a role in the thermal degradation of both PLA and PCL. The tensile properties of both PLA/PCL and PLA/PCL/TiO₂ were significantly reduced through weathering exposure and the incorporation of TiO₂.     

Miscibility behaviour of sulfonylated poly(2,6-dimethyl-1,4-phenylene oxide) copolymers in the blends with poly(styrene-co-maleic anhydride) and with poly(α-methylstyrene-co-maleic anhydride)

Summary The miscibility behaviour of sulfonylated poly(2,6-dimethyl-1,4-phenylene oxide) of the different degree of sulfonylation blended with poly(styrene-co-maleic anhydride) or poly(-methylstyrene-co-maleic anhydride) was studied. The critical degree of sulfonylation for phase separation in these blends was found to be 55 mole % and 66 mole %, respectively. The miscibility behaviour was analyzed on the basis of the mean field treatment and studied by DSC.Dedicated to Professor Dragutin Fle in honor of his 70th birthday     

Thermal properties of di- and triblock copolymers of poly(l-lactide) with poly(oxyethylene) or poly(ε-caprolactone)

High molecular weight di- and triblock copolymers of poly(l-lactide), PLLA, (80 wt%) with a crystallizable flexible second component such as poly(ε-caprolactone), PCL, or poly(oxyethylene), PEO, (20 wt%) were obtained in nearly quantitative yields by ring opening of l-lactide initiated by PCL or PEO hydroxy terminated macromers. The copolymers were characterized by ¹H NMR and FTIR spectroscopy and size exclusion chromatography and showed unimodal and narrow molecular weight distributions. X-ray diffraction measurements revealed high crystallinity (38-56%) of the PLLA blocks and gave no clear evidences of PCL or PEO crystallinity. DMTA and DSC techniques showed a melting behaviour of the copolymers (T_m=174-175 °C; ΔH_m=19-37 J/g) quite similar to that of PLLA. PCL and PLLA segments are immiscible, while PLLA and PEO segments are partially miscible in the amorphous phase. Stress-strain measurements indicated a ductile behaviour of the copolymers, characterized by lower tensile moduli (225-961 Pa) and higher elongations at break (25-134%) with respect to PLLA.     

Modeling of interdiffusion in poly(vinyl acetate)–poly(methyl methacrylate)–toluene multicomponent systems

Work on interdiffusion has been mainly carried out in binary systems in the past, and this work has focused on polymer–solvent (S) systems and polymer blends. To understand and predict the interdiffusion of two solids in the presence of one S, we present a new mathematical model based on the Onsager approach. Within our model, interdiffusion kinetics are described with a modification of the reptation model for long polymer chains, and the chemical potential gradient is used as the driving force behind mass transfer. The chemical potential is calculated with a Flory–Huggins approach. The model was validated with 29 Raman spectroscopy experiments in poly(vinyl acetate)–poly(methyl methacrylate)–toluene systems at 20 °C. Monomer mobilities (L _i,0s) were determined for both polymers to show the independence of L _i,0 from the chain length. The L _i,0s were found to be strongly dependent on the S content. With the knowledge of phase equilibria and L _i,0s, interdiffusion in the ternary polymer–polymer–S system could be predicted by the introduced model. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47092.     

Prevention of poly(vinyl chloride) degradation through organic terephthalamides generated from poly(ethylene terephthalate) waste

The use of organic compounds as thermal stabilizers for poly(vinyl chloride) (PVC) stabilization is the current state of art worldwide owing to their high efficiency and nontoxic residues after degradation. Terephthalamide, N,N′-dimethylterephthalamide and N,N′-dibutylterephthalamide have been prepared via depolymerization of poly(ethylene terephthalate) through an economical and environmentally friendly approach. These compounds have been examined as thermal stabilizers for PVC formulations and found to exhibit high thermal stabilizing effects. Thermal stability measurements were performed using conventional Congo red test method. Color change experiments were conducted by heating the samples at 200 °C in air, and the colored compounds formed were extracted and compared with the help of UV–visible spectroscopy. Fourier transform infrared spectroscopic studies of organic terephthalamides incorporated PVC samples have been performed in order to insight the probable mechanistic aspects involved in thermal stabilization process. Thermogravimetric analysis (TGA) thermograms of PVC sheets loaded with 10 wt % organic terephthalamides have been recorded and were found stable below 200 °C. SEM and energy dispersive X-ray analysis of char residues of TGA samples were performed supporting the proposed thermal stabilizing action of the organic terephthalamides. Furthermore, specific gravity and mechanical performance of the PVC sheets have also been reported assisting in finding suitable commercial applications of PVC formulations. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48022.