Miscibility and intermolecular specific interactions in thermosetting blends of bisphenol S epoxy resin with poly(ethylene oxide)

Thermosetting blends composed of phloroglucinol‐cured bisphenol S epoxy resin and poly(ethylene oxide) (PEO) were prepared via the in situ curing reaction of epoxy in the presence of PEO, which started from initially homogeneous mixtures of diglycidyl ether of bisphenol S, phloroglucinol, and PEO. The miscibility of the blends after and before the curing reaction was established on the basis of thermal analysis (differential scanning calorimetry). Single and composition‐dependent glass‐transition temperatures (T_g's) were observed for all the blend compositions after and before curing. The experimental T_g's could be explained well by the Gordon–Taylor equation. Fourier transform infrared spectroscopy indicated that there were competitive hydrogen‐bonding interactions in the binary thermosetting blends upon the addition of PEO to the system, which was involved with the intramolecular and intermolecular hydrogen‐bonding interactions, that is, OH···O?S, OH···OH, and OH, versus ether oxygen atoms of PEO between crosslinked epoxy and PEO. On the basis of infrared spectroscopy results, it was judged that from weak to strong the strength of the hydrogen‐bonding interactions was in the following order: OH···O?S, OH···OH, and OH versus ether oxygen atoms of PEO. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 359–367, 2005     

Poly(hydroxyether of phenolphthalein) and its blends with poly(ethylene oxide)

Poly(hydroxyether of phenolphthalein) (PPH) was synthesized through the polycondensation of phenolphthalein with epichlorohydrin. It was characterized by Fourier transform infrared (FTIR) spectroscopy, NMR spectroscopy, and differential scanning calorimetry (DSC). The miscibility of the blends of PPH with poly(ethylene oxide) (PEO) was established on the basis of the thermal analysis results. DSC showed that the PPH/PEO blends prepared via casting from N,N‐dimethylformamide possessed single, composition‐dependent glass‐transition temperatures. Therefore, the blends were miscible in the amorphous state for all compositions. FTIR studies indicated that there were competitive hydrogen‐bonding interactions with the addition of PEO to the system, which were involved with OH…O?C〈, ? OH…? OH, and ? OH vs ether oxygen atoms of PEO hydrogen bonding, that is both intramolecular and intermolecular, between PPH and PEO). Some of the hydroxyl stretching vibration bands significantly shifted to higher frequencies, whereas others shifted to lower frequencies, and this suggested the formation of hydrogen bonds between the pendant hydroxyls of PPH and ether oxygen atoms of PEO, which were stronger than the intramolecular hydrogen bonding between hydroxyls and carbonyls of PPH. The FTIR spectra in the range of carbonyl stretching vibrations showed that the hydroxyl‐associated carbonyl groups were partially set free because of the presence of the competitive hydrogen‐bonding interactions. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 466–475, 2003     

Ternary blends of poly(ethylene oxide) and acrylate-based copolymers: Crystallinity, miscibility, interactions and proton conductivity

In the present work, blends of poly(ethylene oxide) (PEO), poly(acrylonitrile-co-methyl acrylate) (PANMA) and poly(4-vinylphenol-co-2-hydroxyethyl methacrylate) (PVPh-HEM) were studied by DSC, FTIR and electrochemical impedance spectroscopy (EIS). PEO/PANMA blends were found to be immiscible, while PEO/PVPh-HEM blends are miscible and PVPh-HEM/PANMA exhibits partial miscibility behaviour. The ternary PEO/PANMA/PVPh-HEM blends exhibited miscible compositions for PVPh-HEM and PEO-rich systems. The miscibility observed is a direct consequence of the hydrogen bond interactions among the polymer chains, in which the phenol groups in PVPh-HEM interact with both PEO and PANMA chains. The proton conductivity of a selected membrane based on the ternary blend containing 60% PEO and doped with H₃PO₄ aqueous solution reached 8 × 10⁻³ Ω⁻¹ cm⁻¹ at room temperature and 3 × 10⁻² Ω⁻¹ cm⁻¹ at 80 °C.     

Synthesis and characterization of a vinyl‐terminated benzoxazine monomer and its blends with poly(ethylene oxide)

A vinyl‐terminated benzoxazine (VB‐a), which could be polymerized through ring‐opening polymerization, was synthesized through the Mannich condensation of bisphenol A, formaldehyde, and allylamine. This VB‐a monomer was then subjected to blending with poly(ethylene oxide) (PEO), followed by thermal curing, to form poly(VB‐a)/PEO blends. The specific interactions, miscibility, morphology, and thermal properties of these blends were investigated with Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry, dynamic mechanical analysis (DMA), and scanning electron microscopy (SEM). Before curing, we found that PEO was miscible with VB‐a, as evidenced by the existence of a single composition‐dependent glass transition temperature (T_g) for each composition. The FTIR spectra revealed the presence of hydrogen‐bonding interactions between the hydroxyl groups of poly(VB‐a) and the ether groups of PEO. Indeed, the ring‐opening reaction and subsequent polymerization of the benzoxazine were facilitated significantly by the presence of PEO. After curing, DMA results indicated that the 50/50 poly(VB‐a)/PEO blend exhibited two values of T_g: one broad peak appeared in the lower temperature region, whereas the other (at ca. 327 °C, in the higher temperature region) was higher than that of pristine poly(VB‐a) (301 °C). The presence of two glass transitions in the blend suggested that this blend system was only partially miscible. Moreover, SEM micrographs indicated that the poly(VB‐a)/PEO blends were heterogeneous. The volume fraction of PEO in the blends had a strong effect on the morphology. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 644–653, 2007     

Synthesis of poly[(2‐oxo‐1,3‐dioxolane‐4‐yl) methyl methacrylate‐co‐ethyl acrylate] by incorporation of carbon dioxide into epoxide polymer and the miscibility behavior of its blends with poly(methyl methacrylate) or poly(vinyl chloride)

This study was related to the investigation of the chemical fixation of carbon dioxide to a copolymer bearing epoxide and the application of the cyclic carbonate group containing copolymer‐to‐polymer blends. In the synthesis of poly[(2‐oxo‐1,3‐dioxolane‐4‐yl) methyl methacrylate‐co‐ethyl acrylate] [poly(DOMA‐co‐EA)] from poly(glycidyl methacrylate‐co‐ethyl acrylate) [poly(GMA‐co‐EA)] and CO₂, quaternary ammonium salts showed good catalytic activity. The films of poly(DOMA‐co‐EA) with poly(methyl methacrylate) (PMMA) or poly(vinyl chloride) (PVC) blends were cast from N,N′‐dimethylformamide solution. The miscibility of the blends of poly(DOMA‐co‐EA) with PMMA or PVC have been investigated both by DSC and visual inspection of the blends. The optical clarity test and DSC analysis showed that poly(DOMA‐co‐EA) containing blends were miscible over the whole composition range. The miscibility behaviors were discussed in terms of Fourier transform infrared spectra and interaction parameters based on the binary interaction model. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1472–1480, 2001     

Miscibility and hydrogen‐bonding interactions in blends of carbon dioxide/epoxy propane copolymer with poly(p‐vinylphenol)

The miscibility and hydrogen‐bonding interactions of carbon dioxide and epoxy propane copolymer to poly(propylene carbonate) (PPC)/poly(p‐vinylphenol) (PVPh) blends were investigated with differential scanning calorimetry (DSC), Fourier transform infrared (FTIR) spectroscopy and X‐ray photoelectron spectroscopy (XPS). The single glass‐transition temperature for each composition showed miscibility over the entire composition range. FTIR indicates the presence of strong hydrogen‐bonding interassociation between the hydroxyl groups of PVPh and the oxygen functional groups of PPC as a function of composition and temperature. XPS results testify to intermolecular hydrogen‐bonding interactions between the oxygen atoms of carbon–oxygen single bonds and carbon–oxygen double bonds in carbonate groups of PPC and the hydroxyl groups of PVPh by the shift of C_1s peaks and the evolution of three novel O_1s peaks in the blends, which supports the suggestion from FTIR analyses. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1957–1964, 2002     

Epoxy resin/poly(ethylene oxide) (PEO) and poly(ε-caprolactone) (PCL) blends cured with 1,3,5-trihydroxybenzene: miscibility and intermolecular interactions

Epoxy resin (ER)/poly(ethylene oxide) (PEO) and/or poly(e-caprolactone) (PCL) blends cured with 1,3,5-trihydroxybenzene (THB) were prepared via the in situ curing reaction of epoxy monomers in the presence of PEO and/or PCL, which started from the initially homogeneous mixtures of DGEBA, THB and PEO and/or PCL. The miscibility and the intermolecular specific interactions in the thermosetting polymer blends were investigated by means of differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR). The two systems displayed single and composition-dependant glass transition temperatures (T _gs), indicating the full miscibility of the thermosetting blends. The experimental T _gs of the blends can be well accounted for by Gordon-Taylor and Kwei equations, respectively. The T _g-composition behaviors were compared with those of poly(hydroxyether of bisphnol A) (Phenoxy) blends with PEO and PCL. It is noted that the formation of crosslinked structure has quite different effects on miscibility and intermolecular hydrogen bonding interactions for the thermosetting polymer blends. In ER/PEO blends, the strength of the intermolecular hydrogen bonding interactions is weaker than that of the self-association in the control epoxy resin, which is in marked contrast to the case of Phenoxy/PEO blends. This suggests that the crosslinking reduces the intermolecular hydrogen bonding interactions, whereas the intermolecular hydrogen bonding interactions were not significantly reduced by the formation of the crosslinking structure in ER/PCL blends.     

Blends of poly(3‐hydroxybutyrate)/4,4′‐thiodiphenol and poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate)/ 4,4′‐thiodiphenol: Specific interaction and properties

The specific interaction between poly(3‐hydroxybutyrate) [P(3HB)] and 4,4′‐thiodiphenol (TDP) and between poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBV) and TDP was investigated by Fourier transform infrared (FTIR) spectroscopy. Interassociated hydrogen bonds were found between the polyester chains and the TDP molecules in the binary blends. The fractions of associated carbonyl groups, F_b 's, in the blends first increased and then decreased as the TDP content increased. The thermal and dynamic mechanical properties of P(3HB)–TDP and PHBV–TDP blends were investigated by differential scanning calorimetry and dynamic mechanical thermal analysis, respectively. Thermal analysis revealed that the P(3HB)–TDP blends possessed eutectic phase behavior. Furthermore, it was found that the thermal and dynamic mechanical properties of P(3HB) and PHBV were greatly modified through blending with TDP. Environmental degradability in river water was evaluated by a biochemical oxygen demand tester, and it was clarified that TDP lowered the degradation rate of P(3HB). The results suggest that TDP is effective in modifying the physical properties as well as the biodegradability of polyesters. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 2891–2900, 2000     

Preparation and Characterization of Blend Films of Poly(Vinyl Alcohol) and Sodium Alginate

Blend films of poly(vinyl alcohol) (PVA) and sodium alginate (NaAlg) were prepared by casting from aqueous solutions. This blend films were characterized by tensile strength test, Fourier transform infrared spectroscopy (FT‐IR), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The miscibility in the blends of PVA and NaAlg was established on the basis of the thermal analysis results. DSC showed that the blends possessed single, composition‐dependent glass transition temperatures (T_gs), indicating that the blends are miscible. FT‐IR studies indicate that there is the intermolecular hydrogen bonding interactions, i.e. –OH…^?OOC– in PVA/NaAlg blends. The blend films also exhibited the higher thermal stability and their mechanical properties improved compared to those of homopolymers.     

Phase behavior and interactions in blends of poly[(butylene adipate)-co-poly(butylene terephthalate)] copolyester with poly(4-vinyl phenol)

Miscibility with a linear T _g–composition relationship was proven for blend of poly(butylene adipate-co-butylene terephthalate) [P(BA-co-BT)] with poly(4-vinyl phenol) (PVPh). In comparison to the blends of PBA/PVPh and poly(butylene terephthalate) (PBT)/PVPh, the Kwei’s T _g model fitting on data for the P(BA-co-BT)/PVPh blend yields a q value between those for the PBA/PVPh and PBT/PVPh blends. The q values suggest that the interaction strength in the P(BA-co-BT)/PVPh blend is not as strong as that in the PBT/PVPh blend. Upon mixing the PVPh into the immiscible blend of PBA and PBT, the ternary PBA/PBT/PVPh blends only exhibits partial miscibility. Full-scale ternary miscibility in whole compositions is not possible owing to the significant ∆χ effect (χ _ij  – χ _ik ). The wavenumber shifts of the hydroxyl IR absorbance band indicates that the H-bonding strength is in decreasing order—PBT/PVPh > P(BA-co-BT)/PVPh > PBA/PVPh—and shows that the BA segment in the copolymer tends to defray interactions between P(BA-co-BT) and PVPh in blends.     

Effect of inert diluent segment on the miscibility behavior of poly(vinylphenol) with poly(acetoxystyrene) blends

Polymer blends of poly(vinylphenol) (PVPh) and poly(styrene‐co‐vinylphenol) with poly(p‐acetoxystyrene) (PAS) were prepared by solution casting from tetrahydrofuran solution. The thermal properties and hydrogen bonding of the blends were investigated by differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy. Although hydrogen bonding existed between the PVPh and PAS segments, the experimental results indicated that PVPh is immiscible with PAS as shown by the existence of two glass‐transition temperatures over the entire composition range by DSC. This phenomenon is attributed to the strong self‐association of PVPh, intramolecular screening, and functional group accessibility effects of the PVPh/PAS blend system. However, the incorporation of an inert diluent moiety such as styrene into the PVPh chain renders the modified polymer to be miscible with PAS. Copolymers containing between 16 and 51 mol % vinylphenol were fully miscible with PAS according to DSC studies. These observed results were caused by the reduction of the strong self‐association of PVPh and the increase of the interassociation between PVPh and PAS segments with the incorporation of styrene on the PVPh chain. According to the Painter‐Coleman association model, the interassociation equilibrium constant of PVPh/PAS blends was determined by a model compound and polymer blend. Good correlation between these two methods was obtained after considering the intramolecular screening and functional group accessibility effect in the polymer blend. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1661–1672, 2002     

Upper critical solution temperature type phase behavior of poly(styrene‐co‐acrylonitrile) blends with poly(styrene‐co‐n‐phenyl maleimide) and their interaction energies

To enhance the heat resistance of poly(styrene‐co‐acrylonitrile‐co‐butadiene), ABS, miscibility of poly(styrene‐co‐acrylonitrile), SAN, with poly(styrene‐co‐n‐phenyl maleimide), SNPMI, having a higher glass transition temperature than SAN was explored. SAN/SNPMI blends casted from solvent were immiscible regardless of copolymer compositions. However, SNPMI copolymer forms homogeneous mixtures with SAN copolymer within specific ranges of copolymer composition upon heating caused by upper critical solution temperature, UCST, type phase behavior. Since immiscibility of solvent casting samples can be driven by solvent effects even though SAN/SNPMI blends are miscible, UCST‐type phase behavior was confirmed by exploring phase reversibility. When copolymer composition of SNPMI was fixed, the phase homogenization temperature of SAN/SNPMI blends was increased as AN content in SAN copolymer increased. To understand the observed phase behavior of SAN/SNPMI blend, interaction energies of blends were calculated from the UCST‐type phase boundaries by using the lattice‐fluid theory combined with a binary interaction model. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 1131–1139, 2008     

Miscibility behavior and hydrogen bonding in blends of poly(vinyl phenyl ketone hydrogenated) and poly(2‐ethyl‐2‐oxazoline)

The miscibility behavior of poly(2‐ethyl‐2‐oxazoline) (PEOx)/poly(vinyl phenyl ketone hydrogenated) (PVPhKH) blends was studied for the entire range of compositions. Differential scanning calorimetry and thermomechanical analysis measurements showed that all the PEOx/PVPhKH blends studied had a single glass‐transition temperature (T_g). The natural tendency of PVPhKH to self‐associate through hydrogen bonding was modified by the presence of PEOx. Partial IR spectra of these blends suggested that amide groups in PEOx and hydroxyl groups in PVPhKH interacted through hydrogen bonding. This physical interaction had a positive influence on the phase behavior of PEOx/PVPhKH blends. The Kwei equation for T_g as a function of the blend composition was satisfactorily used to describe the experimental data. Pure‐component pressure–volume–temperature data were also reported for both PEOx and PVPhKH. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 636–645, 2004     

A DSC study of miscibility and phase separation in crystalline polymer blends of phenolphthalein poly(ether ether sulfone) and poly(ethylene oxide)

The miscibility of blends of phenolphthalein poly(ether ether sulfone) (PES-C) and poly(ethylene oxide) (PEO) was established on the basis of the thermal analysis results. Differential scanning calorimetry (DSC) studies showed that the PES-C/PEO blends prepared by casting from N,N-dimethylformamide (DMF) possessed a single, composition-dependent glass transition temperature (T_g), and thus that PES-C and PEO are miscible in the amorphous state at all compositions at lower temperature. At higher temperature, the blends underwent phase separation, and the PES-C/PEO blend system was found to display a lower critical solution temperature (LCST) behavior. The phase separation process in the blends has also been investigated by using DSC. Annealed at high temperatures, the PES-C/PEO blends exhibited significant changes of thermal properties, such as the enthalpy of crystallization and fusion, temperatures of crystallization and melting, depending on blend composition when phase separation occurred. These changes reflect different characteristics of phase structure in the blends, and were taken as probes to determine phase boundary. From both the thermal analysis and optical microscopy, the phase diagram of the blend system was established. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35 : 1383–1392, 1997     

A thermodynamic analysis of specific interactions in blends of poly(styrene‐co‐N,N‐dimethylacrylamide) and poly(styrene‐co‐acrylic acid). Screening and self‐association effects

In a first step of this contribution, the observed glass transition temperature‐composition behavior of miscible blends of poly(styrene‐co‐N,N‐dimethylacrylamide) (SAD17) containing 17 mol % of N,N‐dimethylacrylamide and poly(styrene‐co‐acrylic acid) (SAA18, SAA27, and SAA32) containing increasing acrylic acid content, are analyzed according to theoretical approaches. Both Kwei and Brostow equations describe well the experimental data though better fits were obtained with the Brostow's approach. The specific interactions involved in these systems are a combination of intra and interassociation hydrogen bonding. The positive deviation from the linear mixing rule of T_g‐composition observed within the SAA18+SAD17 blend system, indicates that interassociation interactions are prevailing. More pronounced intra‐association interactions within the SAA32+SAD17 blend system led to a large negative deviation while a fine balance is established between these two types of interactions within the SAA27+SAD17 blend. A thermodynamic analysis was carried out according to the Painter‐Coleman association model. The miscibility and phase behavior of SAD17+SAA18 and SAD17+SAA27 blends are well predicted. However, this model predicts a partial miscibility of SAD17+SAA32 system. Finally, the fitting parameter free method developed by Coleman to predict the T_g‐composition behavior is applied. This method predicts fairly well the evolution trend of experimental T_gs of the SAA18+SAD17 and SAA27+SAD17 blend systems. However, the compositional dependence of SAA32+SAD17 blend T_g was not predictable by this method. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47:2074–2082, 2009     

Hydrogen bonding interaction and crystallization behavior of poly (butylene succinate‐co‐butylene adipate)/thiodiphenol complexes

The poly (butylene succinate‐co‐butylene adipate) (PBSA)/thiodiphenol (TDP) complexes were prepared by melt blending. Intermolecular hydrogen bonding between carbonyl group of PBSA and hydroxyl group of TDP formed as verified by a combination FTIR and peak fitting technique. As a result, the crystallization temperature, melting temperature, crystallinity and crystallization rate of PBSA decreased with addition of TDP, implying impeded crystallization and reduced lamellar thickness. On the basis of Lauritzen–Hoffman analysis, the fold surface energy (σ_e) and work of chain folding (q) were increased by TDP incorporation. POM observation exhibited concentric ring‐banded spherulites for samples with 10 and 20 wt% TDP. A peculiar ring‐banded pattern with discrepant band spacing was obtained for the first time by addition of 30 wt% TDP, whose formation mechanism remains to be discussed. Copyright © 2016 John Wiley & Sons, Ltd.     

Phase Behavior and Thermal Properties for Binary Blends of Bacterial Poly(3‐hydroxybutyrate‐co‐3‐hydroxyhexanoate)s with Narrow‐Comonomer‐Unit Compositional Distribution

The miscibility and the effect of compositional distribution on physical properties were investigated for binary blends of biosynthesized poly(3‐hydroxybutyrate) [P(3HB)] and comonomer compositionally fractionated poly(3‐hydroxybutyrate‐co‐3‐hydroxyhexanoate)s [P(3HB‐co‐3HH)] with narrow compositional distribution. Biosynthesized P(3HB‐co‐3HH) samples were compositionally fractionated using solvent (chloroform)/nonsolvent (n‐heptane) mixtures. The binary blends of fractionated P(3HB‐co‐3HH)s with different 3HH unit content were prepared by casting from solution in chloroform. The miscibility and the thermal properties of these blends were analyzed by differential scanning calorimetry (DSC). It was found that the two components are miscible in the amorphous phase when the difference in 3HH unit content between the two component polymers of these blends is less than 20 mol‐%, subsequently they are immiscible when the difference is larger than 30 mol‐%. By comparing the thermal properties of the binary blends of fractions, with those for the fractions themselves, and with those for the bacterially as‐produced unfractionated copolyesters, the effects of compositional distribution on the properties of copolyesters were discussed.

Glass transition temperatures of blends PHB/H10, H10/H20, and PHB/H20 versus total 3HH unit content in the blends. The solid lines are the best fits of the experimental results of the P(3HB‐co‐3HH) fractions with narrow compositional distribution.     

Complex phase behavior and state of miscibility in Poly(ethylene glycol)/Poly(l‐lactide‐co‐ε‐caprolactone) Blends

A miscibility and phase behavior study was conducted on poly(ethylene glycol) (PEG)/poly(l ‐lactide‐ε‐caprolactone) (PLA‐co‐CL) blends. A single glass transition evolution was determined by differential scanning calorimetry initially suggesting a miscible system; however, the unusual T_g bias and subsequent morphological study conducted by polarized light optical microscopy (PLOM) and atomic force microscopy (AFM) evidenced a phase separated system for the whole range of blend compositions. PEG spherulites were found in all blends except for the PEG/PLA‐co‐CL 20/80 composition, with no interference of the comonomer in the melting point of PEG (T_m = 64 °C) and only a small one in crystallinity fraction (X_c = 80% vs. 70%). However, a clear continuous decrease in PEG spherulites growth rate (G) with increasing PLA‐co‐CL content was determined in the blends isothermally crystallized at 37 °C, G being 37 µm/min for the neat PEG and 12 µm/min for the 20 wt % PLA‐co‐CL blend. The kinetics interference in crystal growth rate of PEG suggests a diluting effect of the PLA‐co‐CL in the blends; further, PLOM and AFM provided unequivocal evidence of the interfering effect of PLA‐co‐CL on PEG crystal morphology, demonstrating imperfect crystallization in blends with interfibrillar location of the diluting amorphous component. Significantly, AFM images provided also evidence of amorphous phase separation between PEG and PLA‐co‐CL. A true T_g vs. composition diagram is proposed on the basis of the AFM analysis for phase separated PEG/PLA‐co‐CL blends revealing the existence of a second PLA‐co‐CL rich phase. According to the partial miscibility established by AFM analysis, PEG and PLA‐co‐CL rich phases, depending on blend composition, contain respectively an amount of the minority component leading to a system presenting, for every composition, two T_g's that are different of those of pure components. © 2013 Wiley Periodicals, Inc. J. Polym. Sci. Part B: Polym. Phys. 2014 , 52, 111–121     

Miscible blends of poly(ethylene oxide) with brush copolymers of poly(vinyl alcohol)‐graft‐poly(l‐lactide)

Even though poly(ethylene oxide) (PEO) is immiscible with both poly(l ‐lactide) (PLLA) and poly(vinyl alcohol) (PVA), this article shows a working route to obtain miscible blends based on these polymers. The miscibility of these polymers has been analyzed using the solubility parameter approach to choose the proper ratios of the constituents of the blend. Then, PVA has been grafted with l ‐lactide (LLA) through ring‐opening polymerization to obtain a poly(vinyl alcohol)‐graft‐poly(l ‐lactide) (PVA‐g‐PLLA) brush copolymer with 82 mol % LLA according to ¹H and ¹³C NMR spectroscopies. PEO has been blended with the PVA‐g‐PLLA brush copolymer and the miscibility of the system has been analyzed by DSC, FTIR, OM, and SEM. The particular architecture of the blends results in DSC traces lacking clearly distinguishable glass transitions that have been explained considering self‐concentration effects (Lodge and McLeish) and the associated concentration fluctuations. Fortunately, the FTIR analysis is conclusive regarding the miscibility and the specific interactions in these systems. Melting point depression analysis suggests that interactions of intermediate strength and PLOM and SEM reveal homogeneous morphologies for the PEO/PVA‐g‐PLLA blends. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 1217–1226     

Specific interactions and phase behavior of ternary poly(2‐vinylpyridine)/poly(N‐vinyl‐2‐pyrrolidone)/bisphenol A blends

Hydrogen‐bonding interactions between bisphenol A (BPA) and two proton‐accepting polymers, poly(2‐vinylpyridine) (P2VPy) and poly(N‐vinyl‐2‐pyrrolidone) (PVP), were examined by Fourier transform infrared (FTIR) spectroscopy and differential scanning calorimetry (DSC). The Flory–Huggins interaction‐energy densities of BPA/P2VPy and BPA/PVP blends were determined by the melting point depression method. The interaction parameters for both BPA/P2VPy and BPA/PVP blend systems were negative, demonstrating the miscibility of BPA with P2VPy as well as PVP. The miscibility of ternary BPA/P2VPy/PVP blends was examined by DSC, optical observation, and solid‐state nuclear magnetic resonance spectroscopy. The experimental phase behavior of the ternary blend system agreed with the spinodal phase‐separation boundary calculated using the determined interaction‐energy densities. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1125–1134, 2002