Miscibility windows for poly(styrene-co-vinyl phenol) blends with poly(alkyl methacrylate)s: Further comparisons of theoretical predictions to FTIR experimental data

We report the results of theoretical and experimental studies of styrene-co-vinyl phenol (STVPh) copolymer blends with poly(n-octyl methacrylate) (POMA) and poly(n-decyl methacrylate) (PDMA). This work is a natural extension to our recently reported studies of the phase behavior of analogous STVPh blends with poly(n-butyl methacrylate) (PBMA) and poly(n-hexyl methacrylate) (PHMA) where we employed an association model together with parameters obtained from studies of miscible homopolymer blends. The theoretically calculated miscibility maps for STVPh copolymer blends with the homologous series of poly(n-alkyl methacrylates) (PAMA) are in fine agreement with experiment.     

The study of the miscibility and morphology of poly(styrene‐co‐4‐vinylphenol)/poly(propylene carbonate) blends

Blends of poly(propylene carbonate) (PPC) with copolymer poly(styrene‐co‐4‐vinyl phenol) (STVPh) have been studied by electron spin resonance (ESR) spin probe method and Raman spectroscopy. The ESR results indicated that the nitroxide radical existed in a PPC‐rich and an STVPh‐rich micro domain in the blends, corresponding to the fast‐motion and slow‐motion component in the ESR spectra, respectively. And in the temperature dependence composite spectra, the fast‐motion fraction increased with increasing the hydroxyl group content in copolymer STVPh. Moreover, the ESR parameter T_5mT, rotational correlation times (τ_c) and activation energies (E_a) showed similar dependence on the hydroxyl group content as the fast‐motion fraction. It resulted from the enhancement of the hydrogen‐bonding interaction between the hydroxyl groups in STVPh and the carboxyl groups and ether oxygen in PPC. However, the distinct band shift and intensity change among the Raman spectra of pure polymer components and those of the blends were observed. In the carboxyl‐stretching region, the band shifted to lower frequency with increasing the hydroxyl groups. Furthermore, the phase morphologies of the blends were obtained by optical microscopy. All could be concluded that the hydrogen‐bonding interaction between the two components was progressively favorable to the mixing process and was the driving force for the miscibility enhancement in the blends. Copyright © 2004 John Wiley & Sons, Ltd.     

Phase behavior in copolymer blends of poly (p-chlorostyrene-co-o-chlorostyrene) and phenylsulfonylated poly (2,6-dimethyl-1,4-phenylene oxide)

The miscibility of random copolymers of o-chlorostyrene and p-chlorostyrene [P (oClSt-co-pClSt)] with partially phenylsulfonylated poly (2,6-dimethyl-1,4-phenylene oxide) (SPPO) copolymers has been studied, using differential scanning calorimetry (DSC) to establish T_g behavior. It already has been established that the isomeric effect of the chlorine substitution on miscibility is large. Thus the para-chloro-substituted styrenic homopolymer is miscible with all SPPOs containing more than ～ 5 mol % phenylsulfonylation, whereas the ortho-chloro-substituted homopolymer is immiscible with the entire range of SPPO copolymer compositions (and also with the respective homopolymers). As a result of this asymmetric behavior of the homopolymers, the width of the window of miscibility in blends now investigated containing copolymers with high pClSt content and SPPO is much greater than in the corresponding blends containing copolymers with large mole fraction of oClSt. These differences are reflected in the corresponding χ parameters calculated from analysis of the data. It was also found that the miscibility is temperature dependent and that the regime in the copolymer-copolymer composition plane shrank as the equilibrium temperature increased, results indicative of LCST behavior. © 1994 John Wiley & Sons, Inc.     

Macromolecular self-assembly in dilute sequence-controlled block copolymer/homopolymer blends

Conventional block copolymers consist of two long contiguous monomer sequences (‘blocks’) that can, in the same fashion as low-molar-mass surfactants, self-assemble into various microstructural elements (e.g., micelles at low copolymer concentrations) to minimize repulsive contacts in the presence of a parent homopolymer. In this work, we explore the existence of segment-specific interactions, as well as the possibility of tailoring these blend morphologies (and producing altogether new ones), with novel sequence-controlled block copolymers. These copolymers are comprised of at least one block that is a random segment composed of both constituent monomer species. Transmission electron microscopy is employed here to examine the bilayered membranes and channel structures that form in two different series of such copolymers in dilute copolymer/homopolymer blends.     

Phase separation in semicrystalline blends of poly(phenylene sulfide) and poly(ethylene terephthalate). II. Effect of poly(phenylene sulfide) homopolymer solubilization of PPS‐graft‐PET copolymer on morphology and crystallization behavior

The morphology and crystallization behavior of poly(phenylene sulfide) (PPS) and poly(ethylene terephthalate) (PET) blends compatibilized with graft copolymers were investigated. PPS‐blend‐PET compositions were prepared in which the viscosity of the PPS phase was varied to assess the morphological implications. The dispersed‐phase particle size was influenced by the combined effects of the ratio of dispersed‐phase viscosity to continuous‐phase viscosity and reduced interfacial tension due to the addition of PPS‐graft‐PET copolymers to the blends. In the absence of graft copolymer, the finest dispersion of PET in a continuous phase of PPS was achieved when the viscosity ratio between blend components was nearly equal. As expected, PET particle sizes increased as the viscosity ratio diverged from unity. When graft copolymers were added to the blends, fine dispersions of PET were achieved despite large differences in the viscosities of PPS and PET homopolymers. The interfacial activity of the PPS‐graft‐PET copolymer appeared to be related to the molecular weight ratio of the PPS homopolymer to the PPS segment of the graft copolymer (M_H/M_A). With increasing solubilization of the PPS graft copolymer segment by the PPS homopolymer, the particle size of the PET dispersed phase decreased. In crystallization studies, the presence of the PPS phase increased the crystallization temperature of PET. The magnitude of the increase in the PET crystallization temperature coincided with the viscosity ratio and extent of the PPS homopolymer solubilization in the graft copolymer. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 599–610, 2000     

Physical characterization of blends of isotactic poly(butene-1) with ethylene-propylene copolymer

Melt-mixed blends of isotactic poly(butene-1) (PB) with an ethylene-propylene copolymer (EPM) containing 60 wt% PP were studied over the complete composition range. Phase-contrast polarizing microscopy and dynamic mechanical spectroscopy revealed that the blend is heterogeneous. DSC studies of quenched and annealed blends for both PB modifications indicate that total blend crystallinity decreases linearly with the EPM content. Pure PB crystallinity is enhanced to a small degree in the presence of EPM. Tensile behaviour of the blends was good up to moderate EPM levels. It was also demonstrated that blends containing EPM with increased PP content showed synergism in tensile behaviour not exhibited by blends with EPM of lower PP content. Appropriate mechanical models tested over the complete composition and temperature range suggest that the rubbery phase adheres strongly to the PB matrix. Overall, the experimental results support the contention that the system is mechanically compatible, possibly a result of component miscibility at elevated temperatures as predicted on thermodynamic grounds.     

Phase behavior of binary blends of diblock copolymer/homopolymer confined in spherical nanopores

Binary blends of a diblock copolymer (AB) and an incompatible homopolymer (C) confined in spherical cavities are studied using a simulated annealing technique. The phase behavior of the blends is examined for four typical cases, representing the different selectivity of the pore surface to the A, B, and C species. The internal morphology of the spherical polymeric particles is controlled by the homopolymer volume fraction, the degree of confinement, and the composition of the copolymer. Inside a particle, the homopolymers segregate to form one or, under some conditions, two domains; thus, the homopolymers may act as an additional controlling parameter of the shape and symmetry of the copolymer domain. A rich array of confinement-induced novel diblock copolymer morphologies is predicted. In particular, core-shell particles with the copolymers as the shell wrapping around a homopolymer core or a copolymer-homopolymer combined core and Janus-like particles with the copolymers and the homopolymers on different sides are obtained.     

含联苯结构聚醚醚酮酮共聚物和共混物的制备及性能研究

聚醚醚酮（PEEK）是八十年代初投入市场的全芳香结构热塑性耐高温特种工程塑料，它的7’。一143“C，Tm一334C“‘，最大结晶度为48％，典型制品结晶度为20％～30％［”．PEEK可用通常的设备成型，其制件、纤维、涂料及复合材料在电子电器、机械设备、交通运输、宇航、原子能工程、军事等领域有广泛的用途［’j．聚醚醚酮酮（PEEKK）是继PEEK之后，由德国Hoechst公司开发出来的又一种全芳香结构热塑性耐高温特种工程塑料［‘j．为了研究该类聚合物的结构和性能的关系，我们在实验室中合成了PEEKK和含联苯结构聚醚醚酮酮（PE－＊…     

Effects of poly(methyl methacrylate)-block-poly(vinyl acetate) copolymer on the spinodal decomposition of corresponding homopolymer blends

Effects of adding a small amount of poly(methyl methacrylate)-block-poly(vinyl acetate) (PMMA-b-PVAc) to poly(methyl methacrylate)/poly(vinyl acetate) (PMMA/PVAc) blends with a lower critical solution temperature (LCST) phase diagram on the kinetics of late-stage spinodal decomposition (SD) were investigated by time-resolved light scattering at 160°C. It is found that the coarsening process of the structure was slowed down or accelerated upon addition of PMMA-b-PVAc depending on the composition of the block copolymer and the blend. The effect of the block copolymer on the domain size were interpreted as compatibilizing and incompatibilizing effects of the block copolymer on PMMA/PVAc blends based on the evaluation of changes in the stability limits of PMMA/PVAc with the addition of block copolymer using random phase approximation (RPA).     

Design of miscible polyolefin copolymer blends

Theoretical guidelines are established for designing miscible blends of amorphous polyolefin copolymers. On the basis of calculations for an athermal and incompressible model of copolymer melts, limits are placed on the compositions and structural differences between blend components that are consistent with thermodynamic stability of a single liquid phase. Specific cases analyzed include binary blends of random copolymers containing short branches and blends of graft polymers with long flexible branches, either periodically or randomly placed. The predictions are shown to be in good agreement with recent experimental studies of miscibility in model polyolefin copolymer blends. © 1995 John Wiley & Sons, Inc.     

Molecular design of multicomponent polymer systems. VII. Emulsifying effect of poly(ethylene–b–styrene) copolymer in high-density polyethylene/polystyrene blends

Poly(butadiene–b–styrene) copolymers containing a pure, 1,4-PB block have been synthesized by a “living” coordination process. The complete hydrogenation of the PB chain leads accordingly to a high-density polyethylene (HDPE) block. The emulsifying efficiency of such a copolymer (H-7) in HDPE/PS blends is compared with that of a previously reported poly(ethylene–butene–b–styrene) copolymer (SE-7) obtained by the PB hydrogenation of an anionically prepared PB–b–PS. Microscopy examinations demonstrate unambiguously the interfacial activity of both copolymers in HDPE/PS blends. The tensile mechanical properties of the blends are significantly but also differently modified by the two emulsifiers. The copolymer H-7 gives rise to the highest strengths, but, contrary to the copolymer SE-7, provides a poor ductility to the blends. This different behavior is assumed to result in part from the different characteristics of the hydrogenated PB blocks. The elastomeric HPB chain of SE-7 should form at the interface a more or less extended soft zone whereas a rigid interface would result from the cocrystallization of the HPB chain of H-7 with the HDPE homopolymer.     

Compatibility and thermodynamic interaction in random copolymer blends

Some random copolymer blends have been found to be miscible in a certain range of copolymer composition even though any combinations of their corresponding homopolymers are not miscible. The opposite case may exist. These two types of miscibility behaviors have been called miscibility and immiscibility windows, respectively. Such two miscibility behaviors were discussed by application of the equation-of-state theory to copolymer systems. The equation-of-state theory gives two kinds of temperature dependences of the interaction parameter X: (a) a U-shaped curve which is always positive regardless of temperature and (b) a function increasing monotonically from negative to positive values. Infinite molecular weight polymer blends are immiscible over all the temperature in the case (a), while in the case (b) two polymers are miscible below a temperature at which X=0. Applying the equation-of-state theory to random copolymer blends in which miscibility changes with the copolymer composition at a certain temperature to be immiscible → miscible → immiscible, two types of dependences of the temperature-X curve can be obtained: (1) (a) → (b) → (a) dependent on the copolymer composition and (2) (b) regardless of the copolymer composition. For the blends in which miscibility changes with the copolymer composition to be miscible → immiscible → miscible, there can be two types: (3) (b) → (a) → (b) and (4) (b) regardless of the copolymer composition. It may be concluded that socalled miscibility and immiscibility windows should be defined by the types (1) and (3), respectively. The equation-of-state theory for random copolymer systems was applied to the real systems. The blends of poly(vinyl acetate-co-vinyl chloride) and poly(ethylene-co-vinyl acetate) were of the type (1), while it was suggested that the blends of poly(vinyl acetate-co-vinyl chloride) and poly(isobutyl methacrylate-co- butyl methacrylate) may be of the type (4) though this system behaved like an immiscibility window at a certain temperature.     

Crew‐cut aggregates from self‐assembly of blends of polystyrene‐b‐poly(acrylic acid) block copolymers and homopolystyrene in solution

The formation and morphological characteristics of crew‐cut aggregates from blends of polystyrene‐b‐poly(acrylic acid) diblock copolymer and polystyrene homopolymer in solution were studied by static light scattering, transmission electron microscopy and size exclusion chromatography. The crew‐cut aggregates, consisting of a polystyrene core and a poly(acrylic acid) corona, were prepared by direct dissolution of the polymer blends in a selective solvent mixture consisting of 93 wt % dimethylformamide and 7 wt % water. It is found that the aggregation behavior depends strongly on the relative volume fractions of the block copolymer and homopolymer in the blends. This is a result of the difference in solubility between the copolymer and the homopolymer in solution which, in turn, influences their miscibility and mutual solubility and consequently the morphology of the formed crew‐cut aggregates. Specifically, when the homopolymer fraction is low, it is mainly dissolved in the cores of the crew‐cut aggregates formed by the block copolymer. When the homopolymer fraction exceeds its solubility limit in the copolymer micelles, aggregates of another type are formed which contain a major fraction of the homopolymer. These aggregates are usually much larger than the primary micelles and have an internal structure due to the formation of reverse micelles from the dissolved block copolymer chains. The importance of thermodynamic vs. kinetic aspects during the formation of the crew‐cut aggregates is also discussed. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 1469–1484, 1999     

Miscibility of blends of poly(2,6-dimethyl 1,4-phenylene oxide) with polystyrene-based ionomers and copolymers

Blends of poly(2,6-dimethyl 1,4-phenylene oxide) (PPhO) with the copolymer poly(styrene-co-methacrylic acid) (PS-MAA) and the ionomer poly(styrene-co-sodium methacrylate) (PS-MAA-Na), up to 10 mol% co-unit content, were investigated by dynamic mechanical thermal measurements. The PPhO/PS-MAA-Na blends are compared with PS/PS-MAA-Na blends. The blends of PPhO with PS-MAA are no longer miscible at 10 mol% acid content; this is attributed to a copolymer effect induced by the reduction of PS-PPhO interactions due to the presence of the MAA group which does not interact favorably with PPhO. The blends of PPhO with the ionomer are already immiscible at the lowest ion content studied (2.4 mol%), but become increasingly so as ion content is increased. Despite favorable PS-PPhO interactions, these blends are only a little more miscible than the PS/PS-MAA-Na blends. This is attributed to a combination of the increasing importance of the ionomer cluster phase (from which the homopolymer chains presumably are excluded) as ion content is increased, and of a copolymer effect between the homopolymers and the unclustered phase of the ionomer. These results are compared with published data indicating that blends of PPhO with another biphasic ionomer, zinc sulfonated polystyrene, are miscible. The contrasting behavior is rationalized in part by the suggestion that the copolymer effect between PPhO and the unclustered phase of the latter ionomer, but not of the former, is absent; this is related to multiplet structure and sizes. The analysis made of the above systems is extended to predict what might be the miscibility behavior between PPhO and other PS-based ionomer and related copolymer systems. © 1993 John Wiley & Sons, Inc.     

Equilibrium constants and the prediction of miscibility windows for polymer blends containing poly(tetrafluoroethylene-alt-vinyl alcohol)

Theoretical calculations of miscibility windows for binary polymer blends in which one component is an essentially alternating copolymer of tetrafluoroethylene and vinyl alcohol (FVOH) are reported. FVOH has an inherently low solubility parameter [≈ 6.2 (cal. cm^?3)^0.5] that is outside the range commonly encountered in miscible polymer blends and thus represents a stringent test of the predictive capabilities of an association model we have used in previous work. The application of this model requires that we determine dimensionless equilibrium constants describing the self-association of a model compound 3,4-pentafluorobutan-2-ol (PFB) at 25°C from infrared spectroscopic data. Analogous equilibrium constants for FVOH were scaled from those of PFB by taking into account differences in the molar volume of the model and the specific repeat of the copolymer (see M. M. Coleman, J. F. Graf, and P. C. Painter: Specific Interactions and the Miscibility of Polymer Blends, Technomic, Lancaster, PA, 1991). Equilibrium constants describing the inter-association of FVOH with ester type carbonyl groups were obtained from spectroscopic studies of miscible blends with poly(ethyl methacrylate). These equilibrium constant values were then used to calculate theoretical miscibility windows for the complete range of blends of FVOH with polymethacrylates, ethylene-co-methyl acrylate, styrene-co-methyl acrylate, and ethylene-co-vinyl acetate copolymers. Experimental results performed in our laboratories confirm the general validity of the predicted miscibility windows. © 1993 John Wiley & Sons, Inc.     

Block copolymer compatibilizers for polystyrene/poly(dimethylsiloxane) blends

Symmetric polystyrene (PS)–poly(dimethylsiloxane) (PDMS) diblock copolymers were mixed into a 20% dispersion of PDMS in PS. The effect of adding the block copolymer on the blend morphology was examined as a function of the block copolymer molecular weight (M_n,bcp), concentration, and viscosity ratio (η_r). When blended together with the PS and PDMS homopolymers, most of the block copolymer appeared as micelles in the PS matrix. Even when the copolymer was preblended into the PDMS dispersed phase, block copolymer micelles in the PS matrix phase were observed with transmission electron microscopy after mixing. Adding 16 kg/mol PS–PDMS block copolymer dramatically reduced the PDMS particle size, but the morphology, as examined by scanning electron microscopy, was unstable upon thermal annealing. Adding 156 kg/mol block copolymer yielded particle sizes similar to those of blends with 40 or 83 kg/mol block copolymers, but only blends with 83 kg/mol block copolymer were stable after annealing. For a given value of M_n,bcp, a minimum PDMS particle size was observed when η_r ～ 1. When η_r = 2.6, thermally stable, submicrometer particles as small as 0.6 μm were observed after the addition of only 3% PS–PDMS diblock (number‐average molecular weight = 83 kg/mol) to the blend. As little as 1% 83 kg/mol block copolymer was sufficient to stabilize a 20% dispersion of 1.1‐μm PDMS particles in PS. Droplet size reduction was attributed to the prevention of coalescence caused by small amounts of block copolymer at the interface. The conditions under which block copolymer interfacial adsorption and interpenetration were facilitated were explained with Leibler's brush theory. © 2002 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 40: 346–357, 2002; DOI 10.1002/polb.10098     

Compatibilizing effect of a graft copolymer on bacterial poly(3‐hydroxybutyrate)/poly(methyl methacrylate) blends

Blends of isotactic (natural) poly(3‐hydroxybutyrate) (PHB) and poly(methyl methacrylate) (PMMA) are partially miscible, and PHB in excess of 20 wt % segregates as a partially crystalline pure phase. Copolymers containing atactic PHB chains grafted onto a PMMA backbone are used to compatibilize phase‐separated PHB/PMMA blends. Two poly(methyl methacrylate‐g‐hydroxybutyrate) [P(MMA‐g‐HB)] copolymers with different grafting densities and the same length of the grafted chain have been investigated. The copolymer with higher grafting density, containing 67 mol % hydroxybutyrate units, has a beneficial effect on the mechanical properties of PHB/PMMA blends with 30–50% PHB content, which show a remarkable increase in ductility. The main effect of copolymer addition is the inhibition of PHB crystallization. No compatibilizing effect on PHB/PMMA blends with PHB contents higher than 50% is observed with various amounts of P(MMA‐g‐HB) copolymer. In these blends, the graft copolymer is not able to prevent PHB crystallization, and the ternary PHB/PMMA/P(MMA‐g‐HB) blends remain crystalline and brittle. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1390–1399, 2002     

Phase behavior of crystalline blends of poly(tetrafluoroethylene) and of random fluorinated copolymers of tetrafluoroethylene

In the present article, we investigate by differential scanning calorimetry (DSC) the thermal behavior (melting, crystallization, and crystal–crystal transitions) far from equilibrium of blends constituted of two crystalline polymers. In particular, the following blends are examined: PTFE–PFMVE, PTFE–FEP, and FEP–PFMVE where PTFE is poly(tetrafluoroethylene), PFMVE is poly(tetrafluoroethylene‐co‐perfluoromethylvinylether), and FEP is poly(tetrafluoroethylene‐co‐hexafluoropropylene). The two last ones are random tetrafluoroethylene copolymers with small amounts of comonomer. Our results indicate that, under the experimental investigated conditions, the blends containing PTFE do not give cocrystallization on cooling from the melt, although under very rapid crystallization conditions, quenching, the presence of the copolymer would seem to slightly influence PTFE crystallization (lower peak temperatures are observed for the crystalline transitions and the melting with respect to those of the neat homopolymer). The behavior of the FEP–PFMVE blend is completely different; in fact, our results indicate the occurrence of cocrystallization, then miscibility in the crystalline phase, for almost all compositions and all investigated experimental conditions. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 679–689, 1999     

Morphology re-entry in asymmetric PS-PI-PS' triblock copolymer and PS homopolymer blends

Here, we report the morphology variation in a series of PS-b-PI-b-PS' asymmetric triblock copolymer and PS homopolymer (hPS) blends, where PS' and PS are polystyrene blocks with a molecular weight ratio of approximately 0.11 and PI is poly(isoprene). We find that adding a small amount of hPS results in significant order–order transition (OOT) boundary deflection toward higher PS volume fractions f_PS, which is accompanied by morphology re-entry. For example, the neat triblock copolymer with a PS + PS' volume fraction of f_PS = 0.38 exhibits a lamellar microphase; adding a small amount of hPS reverts the morphology into a hexagonal phase with PS cylinders, while further increasing the hPS fraction leads to normal OOTs from PS cylinders to lamellae, to PI cylinders and finally to spheres. The morphology variation reported here is significantly different from that reported in binary blends of diblock or symmetric triblock copolymer with homopolymer. While the domain features of the LAM structure can be correctly reproduced by self-consistent field theory (SCFT), the observed morphology re-entry is absent in the theoretical SCFT phase diagram. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016, 54, 169–179     

The phase behavior of comblike block copolymer A(m+1)B(m)/homopolymer A mixtures

The phase behaviors of comblike block copolymer A(m+1)B(m)/homopolymer A mixtures are studied by using the random phase approximation method and real-space self-consistent field theory. From the spinodals of macrophase separation and microphase separation, we can find that the number of graft and the length of the homopolymer A have great effects on the phase behavior of the blend. For a given composition of comblike block copolymer, increasing the number of graft does not change the macrophase separation spinodal curve but decreases the microphase separation region. The addition of a small quantity of long-chain homopolymer A increases the microphase separation of comblike block copolymer/homopolymer A mixture. However, the addition of short-chain homopolymer A will decrease the phase separation region of comblike block copolymer/homopolymer A mixture. It is also found that the microstructure formed by diblock copolymer is easier to be swelled by homopolymer than that formed by comblike block copolymer. This can be attributed to the architecture difference between the comblike block copolymer and linear block copolymer.