Viscoelastic behavior and submolecular level dynamic heterogeneity of hydrogen‐bonded polymer blends probed by dynamic FTIR spectroscopy

Viscoelastic behavior and submolecular (functional group) level dynamic heterogeneity of hydrogen‐bonded poly(vinyl phenol)/poly(methyl acrylate) (PVPh/PMA) blends were investigated by using dynamic FTIR spectroscopy. It has been found that the viscoelastic behaviors of the blends, measured by the dynamic (in‐phase and quadrature) spectra of both “free” and hydrogen‐bonded carbonyl groups are dependent on the compositions, i.e., the T_g of the blends, and the degree of hydrogen bonding between the two components. In all the blends studied, elastic response of the hydrogen‐bonded carbonyl groups to the applied strain has been found. The free carbonyl groups respond differently to the applied strain in these blends. Essentially, elastic response of the free carbonyl groups to the applied strain is observed in blends with both a high T_g and a higher fraction (～ 40%) of intermolecular hydrogen bonding between PVPh and PMA, and the submolecular level dynamic heterogeneity is suppressed. The free carbonyl group has a viscous component to its response, in blends having a lower fraction (～ 20%) of hydrogen bonds, even at temperatures well below the thermal T_g of the blends, suggesting that there is a degree of submolecular level dynamic heterogeneity in these blends. Almost entirely viscous response of the free carbonyl group is found in blends whose T_g is close to room temperature and fraction of PVPh/PMA hydrogen bonds is very low. The results reported here suggest that dynamic FTIR has considerable potential for studying specific interactions and viscoelastic behaviors in hydrogen‐bonded polymer blends on submolecular level. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Phase behavior of ternary polymer blends with hydrogen bonding

Atactic poly (methyl methacrylate) (aPMMA) was found to be almost completely immiscible with poly(vinyl acetate) (PVAc). Both aPMMA and PVAc are known to be miscible with poly(vinyl phenol) (PVPh) according to literature. Adding of PVPh into immiscible aPMMA/PVAc mixtures is likely to improve their miscibility. Therefore, PVPh can be used as cosolvent to cosolubilize aPMMA and PVAc. A ternary blend consisting of aPMMA, PVAc, and PVPh was prepared and determined calorimetrically in this article. According to the calorimetry data, the ternary blend was determined to be miscible. The reason for the observed miscibility is because the interactions between PVAc and PVPh are similar to those between aPMMA and PVPh. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2797–2802, 2004     

Phase behavior of ternary polymer blends with favorable interactions

Atactic poly(methyl methacrylate) (aPMMA) and poly(vinyl pyrrolidone) (PVP) with a weight‐average molecular weight of 360,000 g/mol were found to be immiscible on the basis of preliminary studies. Poly(styrene‐co‐vinyl phenol) (MPS) with a certain concentration of vinyl phenol groups is known to be miscible with both aPMMA and PVP. Is it possible to homogenize an immiscible aPMMA/PVP pair by the addition of MPS? For this question to be answered, a ternary blend consisting of aPMMA, PVP, and MPS was prepared and measured calorimetrically. The role of MPS between aPMMA and PVP and the effects of different concentrations of vinyl phenol groups on the miscibility of the ternary blends were investigated. According to experimental results, increasing the vinyl phenol contents of MPS has an adverse effect on the miscibility of the ternary blends. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 2064–2070, 2005     

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     

Phase behavior of ternary polymer blends

The effect of varying interaction parameters on the phase diagrams of ternary polymer blends was explored by simulating spinodals through use of the Flory-Huggins lattice theory. Results indicate that miscibility is favored for the case of ternary mixtures of marginally miscible or marginally immiscible pairs where all pair interactions are nearly athermal. Miscibility is restricted for asymmetric ternary blends when one of the polymer pairs is either strongly miscible or strongly immiscible. For symmetric blends of partially immiscible pairs, both two-phase and three-phase miscibility gaps are predicted.     

Free volume as an internal material parameter to probe interfaces in ternary polymer blends: A positron lifetime study

A new method to characterize individual interfaces in ternary polymer blends from experimentally measured fractional free volume from Positron Annihilation Lifetime Spectroscopy (PALS) has been developed. By this, we derive the composition dependent miscibility level in ternary polymer blends. This method has its genesis in KRZ (Kirkwood–Risemann–Zimm) theory which introduces hydrodynamic interaction parameter as a measure of excess friction generated at the interface between dissimilar polymer chains resulting in energy dissipation. The method successfully applied for binary blends has been theoretically modified to suit ternary blends in the present work. The efficacy of this method has been tested for two ternary blends namely polycaprolactone/poly(styrene‐co‐acrylonitrile)/poly(vinyl chloride) (PCL/SAN/PVC) and polycaprolactone/poly(vinyl chloride)/poly(vinyl acetate) (PCL/PVC/PVAc) in different compositions. We obtained a maximum effective hydrodynamic interaction (α_eff) of ?12.60 at composition 80/10/10 of PCL/PVC/PVAc while PCL/SAN/PVC showed ?1.60 at 68/16/16 composition. These results suggest that these compositions produce high miscibility level as compared to other compositions. DSC measurements have also been used to supplement positron results. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 3335–3344, 2013     

Phase behavior and mechanical properties of blends of poly(butylene terephthalate) and poly(amino–ether) resin

The structure, thermal and mechanical properties of blends of poly(butylene terephthalate) (PBT) and a poly(amino–ether) (PAE) barrier resin obtained by direct injection molding are reported. The slight shift of the glass transition temperatures (T_g) of the pure components when blended is attributed to partial miscibility rather than interchange reactions. Both the small strain and the break properties of the blends were close or even above those predicted by the direct rule of mixtures. The specific volume of the blends appeared to be the main reason for the modulus behavior. The linear values of the elongation at break indicated that the blends were compatible, and were attributed to a combination of good adhesion between the two phases of the blends and the small size of the dispersed phases. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 132–139, 2004     

Phase morphology and interfacial characteristics of polycarbonate/acrylonitrile‐ethylene‐propylene‐diene‐styrene blends compatibilized by styrene‐maleic anhydride copolymers

Blends of polycarbonate (PC) and acrylonitrile ‐ ethylene‐propylene‐diene‐styrene (AES) were reactive compatibilized by styrene‐maleic anhydride copolymers (SMA). The changes in phase morphology and interfacial characteristics of the blends as a function of maleic anhydride content of SMA and the concentration of compatibilizer have been systematic studied. The occurrence of reaction between the terminal hydroxyl groups of PC and the maleic anhydride (MA) of compatibilizer was confirmed by fourier transform infrared (FTIR) spectroscopy. A glass transition temperature (T_g) with an intermediate value between T_g(AES) and T_g(PC) was found on differential scanning calorimeter (DSC) curves of PC/AES blends compatibilized with SMA contains high levels of MA. Furthermore, at lower compatibilizer content, increase of the compatibilizer level in blends result in decreasing gap between two T_gs corresponding to the constituent polymers. Small angle X‐ray scattering (SAXS) test results indicated that compatibilizer concentration for the minimum of blend interface layer's thickness was exactly the same as it was when compatibilized PC/AES blend exhibited optimal compatibility in DSC test. The observed morphological changes were consistent well with the DSC and SAXS test results. A new mechanism of interfacial structural development was proposed to explain unusual phenomena of SMA compatibilized PC/AES blends. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42103.     

Phase behavior of semicrystalline polymer blends

The phase behavior of the semicrystalline polymer blend composed of isotactic polypropylene (iPP) and linear low density polyethylene (PE) was studied using small angle X-ray scattering (SAXS) and optical microscopy (OM). Based on the random phase approximation, the iPP/PE interaction parameter, χ, was obtained, and used to construct the iPP/PE phase diagram. The χ values reported in this study are lower than the χ values for deuterium-labeled moieties, measured by small angle neutron scattering (SANS). The predicted phase diagram has upper critical solution temperature (UCST) behavior with a critical temperature of 143 °C for the molecular weights used in this study. OM was used to locate cloud points and the results are consistent with the predicted phase diagram. Since iPP melts above the critical point, care was taken to distinguish phase separation from iPP crystallization by studying the kinetics of iPP crystallization, and the iPP crystallization was discerned from dewetting. In PE-rich blends, the iPP crystallization was suppressed and no dewetting was observed.     

Release behavior from hydrogen‐bonded polymer gels prepared by pressurization

Our previous research showed that a simple ultra‐high‐pressure process made poly(vinyl alcohol) (PVA) solution into a macrogel and nanoparticles. To investigate the release properties of PVA hydrogels prepared by the ultra‐high‐pressure treatment, we prepared hydrogels containing model drugs by pressurizing a PVA solution with Alfa‐G Hesperidin or Oil Blue N as a water‐soluble or an oil‐soluble model drug, respectively. In the case of the oil‐soluble drug, an oil‐in‐water emulsion, Oil Blue N containing dodecane in a PVA solution, was used by homogenization before pressurization. The average diameter and the diameter distribution of oil droplets before and after the ultra‐high‐pressure treatment were almost the same. However, the PVA hydrogel prepared at 10,000 atm for 10 min exhibited the slowest release rate of model drugs. Thus, we found that the release rates of the model drugs from the PVA hydrogels were controlled by the degree of crosslinking in the resulting gels, which was determined from the operation parameters of the ultra‐high‐pressure treatment, such as the pressure, time, and concentration of the PVA solution. Therefore, an ultra‐high‐pressure process is promising for drug‐carrier development because of the nonharmful simple preparation process. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Binary and ternary polymer blends containing poly(vinylidene chloride‐co‐acrylonitrile)

Poly(vinylidene chloride‐co‐acrylonitrile) (Saran F), poly(hydroxy ether of bisphenol A) (phenoxy), poly(styrene‐co‐acrylonitrile) (PSAN), and poly(vinyl phenol) (PVPh) all have the same characteristic: miscibility with atactic poly(methyl methacrylate) (aPMMA). However, the miscibility of Saran F with the other polymer (phenoxy, PSAN, or PVPh) is not guaranteed and was thus investigated. Saran F was found to be miscible only with PSAN but not miscible with phenoxy and PVPh. Because Saran F and PVPh are not miscible, although they are both miscible with aPMMA, aPMMA can thus be used as a potential cosolvent to homogenize PVPh/Saran F. The second part of this report focused on the miscibility of a ternary blend consisting of Saran F, PVPh, and aPMMA to investigate the cosolvent effect of aPMMA. Factors affecting the miscibility were studied. The established phase diagram indicated that the ternary blends with high PVPh/Saran F weight ratio were found to be mostly immiscible. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3068–3073, 2004     

Phase behavior of ternary blends containing dimethylpolycarbonate,tetramethylpolycarbonate and poly[styrene‐co‐(methyl methacrylate)] copolymers (or polystyrene)

The miscibility and phase behavior of ternary blends containing dimethylpolycarbonate (DMPC), tetramethylpolycarbonate (TMPC) and poly[styrene‐co‐(methyl methacrylate)] copolymer (SMMA) have been explored. Ternary blends containing polystyrene (PS) instead of SMMA were also examined. Blends of DMPC with SMMA copolymers (or PS) did not form miscible blends regardless of methyl methacrylate (MMA) content in copolymers. However, DMPC blends with SMMA (or PS) blends become miscible by adding TMPC. The miscible region of ternary blends is compared with the previously determined miscibility region of binary blends having the same chemical components and compositions. The region where the ternary blends are miscible is much narrower than that of binary blends. Based on lattice fluid theory, the observed phase behavior of ternary blends was analyzed. Even though the term representing the Gibbs free energy change of mixing for certain ternary blends had a negative value, blends were immiscible. It was revealed that a negative value of the Gibbs free energy change of mixing was not a sufficient condition for miscible ternary blends because of the asymmetry in the binary interactions involved in ternary blends. Copyright © 2004 Society of Chemical Industry     

Miscibility windows in ternary polymer blends of a polyester,polymethacrylate and poly(styrene‐co‐acrylonitrile)

Miscibility, phase diagrams and morphology of poly(ε‐caprolactone) (PCL)/poly(benzyl methacrylate) (PBzMA)/poly(styrene‐co‐acrylonitrile) (SAN) ternary blends were investigated by differential scanning calorimetry (DSC), optical microscopy (OM), and scanning electron microscopy (SEM). The miscibility window of PCL/PBzMA/SAN ternary blends is influenced by the acrylonitrile (AN) content in the SAN copolymers. At ambient temperature, the ternary polymer blend is completely miscible within a closed‐loop miscibility window. DSC showed only one glass transition temperature (T_g) for PCL/PBzMA/SAN‐17 and PCL/PBzMA/SAN‐25 ternary blends; furthermore, OM and SEM results showed that PCL/PBzMA/SAN‐17 and PCL/PBzMA/SAN‐25 were homogeneous for any composition of the ternary phase diagram. Hence, it demonstrated that miscibility exists for PCL/PBzMA/SAN‐17 and PCL/PBzMA/SAN‐25 ternary blends, but that the ternary system becomes phase‐separated outside these AN contents. Copyright © 2003 Society of Chemical Industry     

Thermal behavior and phase morphology of miscible hydrogen‐bonded blends of poly(ϵ‐caprolactone) and enzymatically polymerized polyphenol

Enzymatically prepared novel polyphenol poly(4,4′‐dihydroxydiphenyl ether) (PDHDPE) is blended to modify the properties of biodegradable polyester poly(?‐caprolactone) (PCL). Since the differential scanning calorimetry data show single composition‐dependent glass transition for each blend, PCL and PDHDPE are found to be miscible in the amorphous phase. The crystallization of PCL is depressed by PDHDPE because PDHDPE reduces the molecular mobility and the flexibility of molecular chains of PCL. The Fourier transform infrared spectra clearly indicate that PCL and PDHDPE interact through strong intermolecular hydrogen bonds formed between the carbonyl groups of PCL and the hydroxyl groups of PDHDPE. The increase of the long period, calculated on the basis of Bragg's law with the measurement of small‐angle X‐ray scattering, is found because the peak position of the profiles of Lorentz‐corrected intensity shifts to smaller angle. With the help of lamellar stack model and one‐dimensional correlation function, the accurate lamellar parameters are calculated. The increase of long period is induced by the increase of crystal thickness. The thermal treatment can effectively modify the thermal stability of PCL/PDHDPE blends with the introduction of an intermolecular coupling of the polymer to give crosslinked and/or branched products. It is also found that the addition of PDHDPE to PCL would obviously increase the Young's modulus of PCL. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 149–160, 2006     

Effect of multiblock copolymers in polymer blends

The use of multiblock copolymers for the compatibilization of immiscible polymer blends is controversially discussed in the literature. Investigations have been carried out to estimate the effect of multiblock copolymers containing segments of a liquid crystalline polyester (LCP) and polysulfone (PSU) segments in blends of the based homopolymers. One goal was to determine whether multiblock copolymers provide an opportunity for compatibilizing PSU/LCP blends. By using PSU/LCP multiblock copolymers with different molecular weights of the blocks in the appropriate binary, solution-casted blends, it was shown that the interpenetration of the polysulfone phase of the block copolymer and the PSU matrix leads to an improved miscibility of the blend. This effect is retained in ternary blends of PSU, LCP, and the multiblock copolymer, assuming a certain critical molecular weight of the multiblock copolymer segments. In addition, some mechanical characteristics of PSU/LCP melt blends such as the E-modulus and fracture strength are improved by adding long-segmented multiblock copolymers. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 2293–2309, 1997     

Pattern formation and morphology in the course of drying a droplet of a ternary polymer solution

A micro‐structured polymer film was prepared by drying a droplet of a ternary polymer solution of polystyrene (PS), poly(vinyl pyrrolidone) (PVP), and chloroform. Within a certain weight ratio of PS to PVP an ordered pattern of cylindrical PVP domains was formed on the film surface. The diameter of the individual PVP domains was in the order of 2–3 μm. The effect of polymer weight ratios on the surface morphology was investigated by atomic force microscopy. Additionally, scanning electron microscopy of cross‐sections of the polymer composite film yielded supplementary information on the bulk morphology and revealed an unexpected complex structure underneath the surface pattern. The reasons for this formation mechanism possibly included aspects of phase separation, convective transport in a drying droplet, and the continuous increase of viscosity during solvent evaporation. At a certain solvent concentration in the evaporation path, it will lead to a vitrification of any structure. The “evolution time”, the time between the onset of phase separation and this “point of vitrification”, will determine the resulting film morphology. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Achieving miscible ternary polymer blends with hydrogen bonding

Poly(vinyl phenol) (PVPh) has previously been found to be successful in making immiscible poly(methyl methacrylate) (PMMA)/poly(vinyl acetate) (PVAc) miscible. Poly(ethyl methacrylate) (PEMA) with one more methyl group than PMMA is also immiscible with PVAc. PEMA and PVAc are miscible with PVPh according to the literature. To determine whether PVPh can also cosolubilize PEMA/PVAc, PVPh samples of two different molecular weights have been mixed in this study with PEMA and PVAc to produce a ternary blend. On the basis of the calorimetry data, the ternary PEMA/PVAc/PVPh blend, regardless of the molecular weight of PVPh, has been determined to be miscible. The reason for the observed miscibility is probably that the interactions between PVAc and PVPh are similar in magnitude to those between PEMA and PVPh. A modified Kwei equation based on the binary interaction parameters proposed previously is used to describe the experimental glass‐transition temperature of the miscible ternary blend almost quantitatively well. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 643–652, 2006     

Compatibilization and morphology development of immiscible ternary polymer blends

We report a novel and effective strategy that compatibilizes three immiscible polymers, polyolefins, styrene polymers, and engineering plastics, achieved by using a polyolefin-based multi-phase compatibilizer. Compatibilizing effect and morphology development are investigated in a model ternary immiscible polymer blends consisting of polypropylene (PP)/polystyrene(PS)/polyamide(PA6) and a multi-phase compatibilizer (PP-g-(MAH-co-St) as prepared by maleic anhydride (MAH) and styrene (St) dual monomers melt grafting PP. Scanning electron microscopy (SEM) results indicate that, as a multi-phase compatibilizer, PP-g-(MAH-co-St) shows effective compatibilization in the PP/PS/PA6 blends. The particle size of both PS and PA6 is greatly decreased due to the addition of multi-phase compatibilizer, while the interfacial adhesion in immiscible pairs is increased. This good compatibilizing effect is promising for developing a new, technologically attractive method for achieving compatibilization of immiscible multi-component polymer blends as well as for recycling and reusing of such blends. For phase morphology development, the morphology of PP/PS/PA6 (70/15/15) uncompatibilized blend reveals that the blend is constituted from PP matrix in which are dispersed composite droplets of PA6 core encapsulated by PS phase. Whereas, the compatibilized blend shows the three components strongly interact with each other, i.e. multi-phase compatibilizer has good compatibilization between the various immiscible pairs. For the 40/30/30 blend, the morphology changed from a three-phase co-continuous morphology (uncompatibilized) to the dispersed droplets of PA6 and PS in the PP matrix (compatibilized).     

Polymerization‐induced phase separation and resulting thermomechanical properties of thermosetting/reactive nonlinear polymer blends: A review

Thermosets, which have a highly crosslinked structure, play a pivotal role in high‐performance composite materials because of their excellent mechanical properties, including their high modulus, high strength, and high glass‐transition temperature. In general, however, thermosets are brittle materials with a toughness and elongation at break that are unsatisfactory for many applications, especially at high temperatures. The key factor that can greatly influence the toughness of a thermoset material is its cured microstructure or nanostructure. Recently, it has been revealed that the introduction of a reactive modifier into a multicomponent thermosetting prepolymer is a versatile way to finely tune the polymerization‐induced phase separation (PIPS) and the microstructure and thermomechanical properties of the resulting thermosets. This review focuses first on the advancement of the methods used to study the PIPS of thermosetting prepolymers. I go on to discuss factors influencing the thermodynamic and the kinetic behavior of PIPS and the resulting morphology and thermomechanical properties of thermosetting blends obtained when nonlinear reactive modifiers are incorporated. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Nonlinear phase‐separation behavior of poly(methyl methacrylate)/poly(styrene‐co‐maleic anhydride) blends

The nonlinear phase‐separation behavior of poly(methyl methacrylate)/poly(styrene‐co‐maleic anhydride) (PMMA/SMA) blends over wide appropriate temperature and heating rate ranges was studied using time‐resolved small‐angle laser light scattering. During the non‐isothermal process, a quantitative logarithm function was established to describe the relationship between cloud point (T_c) and heating rate (k) as given by T_c = Alnk + T₀, in which the parameter A, reflecting the heating rate dependence, is much different for different compositions due to phase‐separation rate and activation energy difference. For the isothermal phase‐separation process, an Arrhenius‐like equation was successfully applied to describe the temperature dependence of the apparent diffusion coefficient (D_app) and the relaxation time (τ) of the early stage as well as the late stage of spinodal decomposition (SD) of PMMA/SMA blends. Based on the successful application of the Arrhenius‐like equation, the related activation energies could be obtained from D_app and τ of the early and late stages of SD, respectively. In addition, these results indicate that it is possible to predict the temperature dependence of the phase‐separation behavior of binary polymer mixtures during isothermal annealing over a range of 100 °C above the glass transition temperature using the Arrhenius‐like equation. © 2012 Society of Chemical Industry