Poly(hydroxyether sulfone) and its blends with poly(ethylene oxide): miscibility, phase behavior and hydrogen bonding interactions

Poly(hydroxyether sulfone) (PHES) was synthesized through polycondensation of bisphenol S with epichlorohydrin. It was characterized by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance spectroscopy and differential scanning calorimetry (DSC). The miscibility in the blends of PHES with poly(ethylene oxide) (PEO) was established on the basis of the thermal analysis results. DSC showed that the PHES/PEO blends prepared by casting from N,N-dimethylformamide (DMF) possessed single, composition-dependent glass transition temperatures (T_gs), indicating that the blends are miscible in amorphous state. At elevated temperatures, the PHES/PEO blends underwent phase separation. The phase behavior was investigated by optical microscope and the cloud point curve was determined. A typical lower critical solution temperature behavior was observed in the moderate temperature range for this blend system. FTIR studies indicate that there are the competitive hydrogen bonding interactions upon adding PEO to the system, which was involved with the intramolecular and intermolecular hydrogen bonding interactions, i.e. -OH?OS, -OH?-OH and -OH versus ether oxygen atoms of PEO between PHES and PEO. In terms of the infrared spectroscopic investigation, it is judged that from weak to strong the strength of the hydrogen bonding interactions is in the following order: -OH?OS, -OH?-OH and -OH versus ether oxygen atoms of PEO.     

The study of hydrogen bonding and miscibility in poly(vinylpyridines) with phenolic resin

The hydrogen bonding and miscibility behaviors of poly(2-vinylpyridine) (P2VP) or poly(4-vinylpyridine) (P4VP) with phenolic resin were investigated by differential scanning calorimetry and Fourier transform infrared spectroscopy (FTIR). These blends have a single glass transition over the entire composition range indicating that these blends are able to form a miscible phase due to the formation of inter-molecular hydrogen bonding between hydroxyl of phenolic and pyridine ring of poly(vinylpyridines). Furthermore, FTIR studies on the hydrogen-bonding interaction between the hydroxyl group of phenolic and pyridine ring of poly(vinylpyridines) at various compositions and temperatures indicate that the greater inter-association for P4VP than P2VP due to the steric hindrance effect on specific interaction between these two polymers. Finally, inter-association equilibrium constants of phenolic/P2VP and phenolic/P4VP blends were determined by model compounds.     

Kraft lignin/poly(ethylene oxide) blends: Effect of lignin structure on miscibility and hydrogen bonding

Blends of poly(ethylene oxide) (PEO) with softwood kraft lignin (SKL) were prepared by thermal blending. The miscibility behavior and hydrogen bonding of the blends were investigated by differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) spectroscopy. The experimental results indicate that PEO was miscible with SKL, as shown by the existence of a single glass‐transition temperature over the entire composition range by DSC. In addition, a negative polymer–polymer interaction energy density was calculated on the basis of the melting point depression of PEO. The formation of strong intermolecular hydrogen bonding was detected by FTIR analysis. A comparison of the results obtained for the SKL/PEO blend system with those previously observed for a hardwood kraft lignin/PEO system revealed the existence of stronger hydrogen bonding within the SKL/PEO blends but weaker overall intermolecular interactions between components; this suggested that more than just hydrogen bonding was involved in the determination of the blend behavior in the kraft lignin/PEO blends. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1437–1444, 2005     

Blends of poly(ethylene oxide) and poly(4-vinylphenol-co-2-hydroxyethyl methacrylate): thermal analysis, morphological behaviour and specific interactions

DSC and optical microscopy were used to determine the miscibility and crystallinity of blends of poly(ethylene oxide) (PEO) with poly(4-vinylphenol-co-2-hydroxyethyl methacrylate) (PVPh-HEM). A single glass transition temperature was observed for all blends, indicating miscibility. A progressive decrease in the degree of crystallinity and in the size of the PEO spherullites is observed, as PVPh-HEM is added. FTIR was used to probe the intermolecular specific interactions of the blends and the miscibility of the blend is mainly attributed to PVPh-HEM/PEO intermolecular interactions via hydrogen bonding.     

The totally miscible in ternary hydrogen‐bonded polymer blend of poly(vinyl phenol)/phenoxy/phenolic

The individual binary polymer blends of phenolic/phenoxy, phenolic/poly(vinyl phenol) (PVPh), and phenoxy/PVPh have specific interaction through intermolecular hydrogen bonding of hydroxyl–hydroxyl group to form homogeneous miscible phase. In addition, the miscibility and hydrogen bonding behaviors of ternary hydrogen bond blends of phenolic/phenoxy/PVPh were investigated by using differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy, and optical microscopy. According to the DSC analysis, every composition of the ternary blend shows single glass transition temperature (T_g), indicating that this ternary hydrogen‐bonded blend is totally miscible. The interassociation equilibrium constant between each binary blend was calculated from the appropriate model compounds. The interassociation equilibrium constant (K_A) of each individually binary blend is higher than any self‐association equilibrium constant (K_B), resulting in the hydroxyl group tending to form interassociation hydrogen bond. Photographs of optical microscopy show this ternary blend possess lower critical solution temperature (LCST) phase diagram. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Influence of intramolecular specific interactions on phase behavior of epoxy resin and poly(ε-caprolactone) blends cured with aromatic amines

Two aromatic amines were used as the curing agents to prepare the thermosetting blends of epoxy and poly(ε-caprolactone) (PCL). When cured with 4,4′-methylenebis(2-chloroaniline) (MOCA), the thermosetting blends are miscible in the amorphous state in the entire composition, which was evidenced by the behavior of single, and composition-dependent glass transition temperatures (T_g's) in terms of thermal analysis. Fourier transform infrared spectroscopy (FTIR) showed that there are the intermolecular specific interactions (viz. hydrogen bonding) between the component polymers. However, the 4,4′-diaminodiphenylsulfone (DDS)-cured epoxy forms the immiscible blends with PCL. The blends displayed a typical reaction-induced phase separation morphology. The phase behavior seems to be more than the expected since it was ever proposed that there would be the intermolecular specific interactions between amine-cured epoxy and PCL, which would fulfill the miscibility of the systems. To interpret the phase behavior, we investigated that the miscibility and intermolecular specific interactions in the blends of model compounds and linear homologues of epoxy with PCL. It was observed that in MOCA-cured blends there were much stronger intermolecular specific interactions than in DDS-cured counterparts. The weaker intermolecular specific interactions between DDS-cured epoxy and PCL resulted from the formation of the intramolecular hydrogen bonding interactions within DDS-crosslinked epoxy, which were involved with the sulfonyl groups and the secondary hydroxyls. The intramolecular association could suppress the formation of the strong intermolecular hydrogen bonding interactions between carbonyls and hydroxyls of amine-cured epoxy, which are sufficient to fulfill the homogenization of the system during the in situ polymerization. Therefore, the presence of the intramolecular specific interactions between sulfonyl and hydroxyl groups was taken as the origin of phase-separated morphology for DDS-cured blends of epoxy with PCL.     

Preparation and characterization of novolac type phenolic resin blended with poly(dimethylsiloxane adipamide)

Phenolic resin/poly(dimethylsiloxane adipamide) (PDMSA) blends, which have been prepared, show miscibility due to intermolecular H‐bonding existing between phenolic resin and the PDMSA. The specific H‐bonding of novolac type phenolic/PDMSA blends was characterized by means of glass transition temperature behavior and Fourier Transform Infrared Spectroscopy (FTIR). The strength of intermolecular H‐bonding within the phenolic blend is a function of the H‐bonded group of the PDMSA modifier and corresponds to the deviation glass transition temperature (ΔT_g). Phenolic/PDMSA blends were completely miscible, as confirmed by the T_g study. The FTIR result is in good agreement with the inference from T_g behavior. The char yield of phenolic/PDMSA corresponds to the phenolic resin content. The molecular mobility of phenolic/PDMSA blends increases with PDMSA content in the phenolic‐rich region. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 984–992, 2002     

Miscibility and mechanical properties of an amine‐cured epoxy resin blended with poly(ethylene oxide)

Blends composed of diaminodiphenylmethane bisphenol‐A epoxy resin and poly(ethylene oxide) (PEO) were prepared via in situ curing reaction of epoxy in the presence of PEO. The miscibility of the blends before and after curing was established by thermal (differential scanning calorimetry, DSC), microstructural (atomic force microscopy) and dynamic mechanical analysis. Fourier transform infrared spectroscopy indicated that the OH groups developed through cure reactions interact by hydrogen bonding with PEO. After crystallinity analysis by DSC, the interaction parameter was determined through the depression of the equilibrium melting temperature. Mechanical properties of the miscible blends do not show any significant change, although improvement of fracture toughness has been observed with respect to the matrix properties. Copyright © 2006 Society of Chemical Industry     

Studies on polyethylene oxide and phenolic resin blends

Blends of poly(ethylene oxide) (PEO) and novolac type phenolic resin were prepared by a solution cast method using acetonitrile as a solvent. In this work, we have investigated the PEO/phenolic blends having low phenolic content (0 to 30 wt %) with the objective in mind to design a crystallizable component for a shape memory polymer system having adjustable switching temperature. The blends were characterized by Fourier transform infrared (FTIR) spectroscopy, polarized optical microscopy (POM), and differential scanning calorimetry (DSC). The rate of crystallization and crystallinity (calculated from heat of crystallization value) decrease with increase in novolac content. FTIR analysis indicates the existence of H‐bonding between hydroxyl groups of novolac and ether groups of PEO. POM studies indicate that size of Maltese cross section decreases with increase in novolac content and in the blends containing higher novolac content less regular leaf like texture was obtained. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Effect of bisphenol A on the miscibility,phase morphology,and specific interaction in immiscible biodegradable poly(ε‐caprolactone)/poly(L‐lactide) blends

We have investigated the enhancement in miscibility, upon addition of bisphenol A (BPA) of immiscible binary biodegradable blends of poly(ε‐caprolactone) (PCL) and poly(L ‐lactide) (PLLA). That BPA is miscible with both PCL and PLLA was proven by the single value of T_g observed by differential scanning calorimetry (DSC) analyses over the entire range of compositions. At various compositions and temperatures, Fourier transform infrared spectroscopy confirmed that intermolecular hydrogen bonding existed between the hydroxyl group of BPA and the carbonyl groups of PCL and PLLA. The addition of BPA enhances the miscibility of the immiscible PCL/PLLA binary blend and transforms it into a miscible blend at room temperature when a sufficient quantity of the BPA is present. In addition, optical microscopy (OM) measurements of the phase morphologies of ternary BPA/PCL/PLLA blends at different temperatures indicated an upper critical solution temperature (UCST) phase diagram, since the ΔK effect became smaller at higher temperature (200°C) than at room temperature. An analysis of infrared spectra recorded at different temperatures correlated well with the OM analyses. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1146–1161, 2006     

Miscibility and specific interactions in blends of poly(vinyl phenyl ketone hydrogenated) with poly(2,6‐dimethyl‐1,4‐phenylene oxide)

The miscibility behavior of poly(vinyl phenyl ketone hydrogenated) (PVPhKH) and poly(2,6‐dimethyl‐1,4‐phenylene oxide) (PPO) are studied by differential scanning calorimetry, thermomechanical analysis, and FTIR spectroscopy. Two miscibility windows between 10 to 40 and 60 to 90 wt % PPO are detected. Only the blend with 50 wt % PPO is immiscible. The best fit of the Gordon–Taylor equation of the experimental glass‐transition temperatures for miscible PVPhKH/PPO blends is shown. A study by FTIR spectroscopy suggests that hydrogen bonding interactions are formed between the hydroxyl groups of PVPhKH and the ether groups of PPO. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1887–1892, 2004     

Intra- and Intermolecular Hydrogen Bonding in Miscible Blends of CO2/Epoxy Cyclohexene Copolymer with Poly(Vinyl Phenol)

In this study, we synthesized a poly(cyclohexene carbonate) (PCHC) through alternative ring-opening copolymerization of CO₂ with cyclohexene oxide (CHO) mediated by a binary LZn₂OAc₂ catalyst at a mild temperature. A two-dimensional Fourier transform infrared (2D FTIR) spectroscopy indicated that strong intramolecular [C–H···O=C] hydrogen bonding (H-bonding) occurred in the PCHC copolymer, thereby weakening its intermolecular interactions and making it difficult to form miscible blends with other polymers. Nevertheless, blends of PCHC with poly(vinyl phenol) (PVPh), a strong hydrogen bond donor, were miscible because intermolecular H-bonding formed between the PCHC C=O units and the PVPh OH units, as evidenced through solid state NMR and one-dimensional and 2D FTIR spectroscopic analyses. Because the intermolecular H-bonding in the PCHC/PVPh binary blends were relatively weak, a negative deviation from linearity occurred in the glass transition temperatures (T_g). We measured a single proton spin-lattice relaxation time from solid state NMR spectra recorded in the rotating frame [T_1ρ(H)], indicating full miscibility on the order of 2–3 nm; nevertheless, the relaxation time exhibited a positive deviation from linearity, indicating that the hydrogen bonding interactions were weak, and that the flexibility of the main chain was possibly responsible for the negative deviation in the values of T_g.     

Miscibility of polymethylmethacrylate and polyethyleneglycol blends in tetrahydrofuran

The miscibility of polymethylmethacrylate (PMMA) and polyethyleneglycol (PEG) blends in tetrahydrofuran (THF) has been investigated by viscosity, density, refractive index, and ultrasonic velocity studies. Various interaction parameters such as polymer–solvent and blend–solvent interaction parameters and heat of mixing have been calculated using the viscosity, density, and ultrasonic velocity data. The results indicated the existence of positive interactions in the blend polymer solutions and that they are miscible in THF in the entire composition range. The study also revealed that variation in the temperature does not affect the miscibility of PMMA and PEG blends in THF significantly. The presence of hydrogen bonding in the blends in the solid state has also been indicated by FTIR studies. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Inorganic-organic interpenetrating polymer networks involving polyhedral oligomeric silsesquioxane and poly(ethylene oxide)

A novel organic-inorganic interpenetrating polymer network (IPN) was prepared via in situ crosslinking between octa(propylglycidyl ether) polyhedral oligomeric silsesquioxane (OpePOSS) and 2,2-bis(4-hydroxyphenyl)propane in the presence of poly(ethylene oxide) (PEO). The miscibility and intermolecular specific interactions of the IPNs were investigated by means of differential scanning calorimetry (DSC), transmission electron microscopy (TEM) and Fourier transform infrared (FTIR) spectroscopy. In view of the results of calorimetric analysis and morphological observation, it is judged that the components of the organic-inorganic IPNs are fully miscible. The FTIR spectroscopy shows that there are inter-component hydrogen bonding interactions between the POSS network and PEO. The measurements of static contact angle show that the hydrophilicity (and/or the surface free energy) of the organic-inorganic IPNs increased with the addition of the miscible and water-soluble polymer (i.e., PEO). Thermogravimetric analysis (TGA) shows that the thermal stability of the IPNs was quite dependent on the mass ratios of the POSS network to PEO.     

The study of poly(styrene‐co‐p‐(hexafluoro‐2‐hydroxylisopropyl)‐α‐methylstyrene)/poly(ethylene oxide) blends

Different hydroxyl content poly(styrene‐co‐p‐(hexafluoro‐2‐hydroxylisopropyl)‐α‐methylstyene) [PS(OH)‐X] copolymers were synthesized and blends with 2,2,6,6‐tetramrthyl‐piperdine‐1‐oxyl end spin‐labeled PEO [SLPEO] were prepared. The miscibility behavior of all the blends was predicted by comparing the critical miscible polymer–polymer interaction parameter (χ_crit) with the polymer–polymer interaction parameter (χ). The micro heterogeneity, chain motion, and hydrogen bonding interaction of the blends were investigated by the ESR spin label method. Two spectral components with different rates of motion were observed in the ESR composite spectra of all the blends, indicating the existence of microheterogeneity at the molecular level. According to the variations of ESR spectral parameters T_a, T_d, ΔT, T_50G and τ_c, with the increasing hydroxyl content in blends, it was shown that the extent of miscibility was progressively enhanced due to the controllable hydrogen bonding interaction between the hydroxyl in PS(OH) and the ether oxygen in PEO. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2312–2317, 2004     

Miscibility in blends of linear and branched poly(ethylene oxide) with methacrylate derivative random copolymers and estimation of segmental χ parameters

Miscibility in the blends of poly(ethylene oxide) (PEO) with n-hexyl methacrylate-methyl methacrylate random copolymers (HMA-MMA) and 2-ethylhexyl methacrylate-MMA random copolymers (EHMA-MMA) was evaluated using glass transition and light scattering methods. EHMA-MMA was more miscible with PEO than HMA-MMA. Both blends of PEO with HMA-MMA and EHMA-MMA showed UCST-type miscibility although homopolymer blends PEO/PMMA were predicted to be of LCST-type. This was attributed to an increase in the exchange enthalpy with increasing HMA or EHMA composition in the random copolymer. From the copolymer composition dependence of miscibility the segmental χ parameters of HMA/MMA, EHMA/MMA, EO/HMA and EO/EHMA were estimated using the Flory-Huggins theory extended to random copolymer systems. Miscibility in the blends of branched PEO with HMA-MMA whose HMA copolymer composition was 0.16 was compared with that in the linear PEO blends. The former blends were more miscible with HMA-MMA than the latter one by about 35 °C at the maximum cloud point temperature.     

Miscibility and hydrogen bonding in blends of poly(vinyl acetate) with phenolic resin

The miscibility of phenolic resin and poly(vinyl acetate) (PVAc) blends was investigated by differential scanning calorimeter (DSC), Fourier transform infrared spectroscopy (FT-IR) and solid state ¹³C nuclear magnetic resonance (NMR). This blend displays single glass transition temperature (T_g) over entire compositions indicating that this blend system is miscible in the amorphous phase due to the formation of hydrogen bonding between hydroxyl groups of phenolic resin and carbonyl groups of PVAc. Quantitative measurements on fraction of hydrogen-bonded carbonyl group using both ¹³C solid-state NMR and FT-IR analyses result in good agreement between these two spectroscopic techniques. According to the proton spin-lattice relaxation time in the rotating frame (T_1ρ^H), the phenolic/PVAc blend is intimately mixed on a scale less than 2-3 nm. Furthermore, the inter-association equilibrium constant and its related enthalpy of phenolic/PVAc blends were determined as a function of temperatures by infrared spectra based on the Painter-Coleman association model.     

Molecular dynamics and dissipative particle dynamics simulations for the miscibility of poly(ethylene oxide)/poly(vinyl chloride) blends

The miscibility of poly(ethylene oxide) (PEO)/poly(vinyl chloride) (PVC) blends are investigated by atomistic molecular dynamics and mesoscale dissipative dynamics simulations. The specific volumes of three PEO/PVC blends (with weight ratio at 70/30, 50/50 and 30/70) as well as pure PEO and PVC are examined as a function of temperature. The glass transition temperatures are estimated to be 251, 268, 280, 313 and 350 K for pure PEO, PEO/PVC 70/30, 50/50, 30/70 and pure PVC. Among different energy contributions, the torsion and van der Waals energies exhibit pronounced kinks versus temperature. The Flory-Huggins parameters determined from the cohesive energy densities and the radial distribution functions of the inter-molecular atoms suggest that PEO/PVC 70/30 and 30/70 blends are more miscible than 50/50 blend. This is further supported by the morphologies of PEO/PVC blends, in which the 50/50 blend exhibits segregated domains implying a weak phase separation. Hydrogen bonds are found to form between O atoms of PEO and H atoms of PVC, with a larger degree in PEO/PVC 70/30 and 30/70 blends than in 50/50 blend. The addition of PVC into PEO suppresses the mobility of PEO chains, which is consistent with the experiment observation of decreased crystallization rate as well as crystallization temperature of PEO.     

Hydrogen bonding,miscibility, crystallization,and thermal stability in blends of biodegradable polyhydroxyalkanoates and polar small molecules of 4‐tert‐butylphenol

The hydrogen bonding, miscibility, crystallization, and thermal stability of poly(3‐hydroxybutyrate) (PHB)/4‐tert‐butylphenol (BOH) blends and poly(3‐hydroxybutyrate‐co‐3‐hydroxyhexanoate) [P(3HB‐3HHx)]/BOH blends were investigated by Fourier transform infrared (FTIR) spectroscopy, solid‐state¹³C‐NMR, differential scanning calorimetry, wide‐angle X‐ray diffraction (WAXD), and thermogravimetric analysis. The results of FTIR spectroscopy and solid‐state¹³C‐NMR show that intermolecular hydrogen bonds existed between the two components in the blends and that the interaction was caused by the carbonyl groups in the amorphous phase of both polyesters and the hydroxyl groups of BOH. With increasing BOH content, the chain mobility of both the PHB and P(3HB‐3HHx) components was improved. After the samples were quenched, the detected single glass‐transition temperatures decreased with composition, indicating that both PHB/BOH and P(3HB‐3HHx)/BOH were miscible blends in the melt. Moreover, as BOH content increased, the melting temperatures of PHB and P(3HB‐3HHx) clearly decreased, which implied that their crystallization was suppressed by the addition of BOH. Although the crystallinity of PHB and P(3HB‐3HHx) components decreased with increasing BOH content in the blends, their crystal structures were hardly affected after they were blended with BOH, which was further proven by WAXD results. In addition, the thermal stability of PHB was improved by a smaller amount of BOH.     

Miscible blends containing bacterial poly(3‐hydroxyvalerate) and poly(p‐vinyl phenol)

The miscibility of poly(3‐hydroxyvalerate) (PHV)/poly(p‐vinyl phenol) (PVPh) blends has been studied by differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) spectroscopy. The blends are miscible as shown by the existence of a single glass transition temperature (T_g) and a depression of the equilibrium melting temperature of PHV in each blend. The interaction parameter was found to be −1.2 based on the analysis of melting point depression data using the Nishi–Wang equation. Hydrogen‐bonding interactions exist between the carbonyl groups of PHV and the hydroxyl groups of PVPh as evidenced by FTIR spectra. The crystallization of PHV is significantly hindered by the addition of PVPh. The addition of 50 wt % PVPh can totally prevent PHV from cold crystallization. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 383–388, 1999