Block Copolymer Blends Research Articles

Effect of block copolymer architecture on compatibility: 2. Epoxidized styrene-butadiene star block copolymers with chlorinated polymers

The compatibility behaviour of an epoxidized styrene-butadiene three-arm block copolymer ((ESB) 3) with chlorinated polyethylene (CPE) at two degrees of chlorination (36 and 48 wt%) and with poly(vinyl chloride) was investigated over the complete composition range. The techniques used were dynamic mechanical analysis, differential scanning calorimetry and tensile testing. The results were compared with epoxidized block copolymer blends of different architectures, studied before: a linear ESB, a branched E(SB) n and an SBS. The results indicate that miscibility is reduced along the series ESB>(ESB) 3>E(SB) n , at the same level of epoxidation. Additional data on tensile properties on (ESB) 3 and E(SB) n blends are also reported. A method is also described to obtain epoxidized semicrystalline poly(hydrocarbons), which when blended with CPE showed a T m depression. This allowed the determination of the interaction parameter χ 12 of epoxidized poly(hydrocarbon)/chlorinated polymer using the well established method.

Amorphous-crystalline block copolymer and amorphous homopolymer blends. 1. A preliminary report

The frequency dependence of G' and G suggests that the diblock ethylene-propylene copolymer (DEP, M w = 99100) forms a microdomain in the melt state. Two series of blends of DEP (M w = 113000) and atactic polypropylene (M w = 190000, APP190) and then DEP113 and APP15 were studied by DSC and TEM. The DSC and TEM results can be interpreted in the framework of the currently accepted microphase-separation model for homopolymer/diblock copolymer blends.

Ordered structure in blends of block copolymers. 1. Miscibility criterion for lamellar block copolymers

Morphology of binary mixtures of poly(styrene-block-isoprene) (SI) having different compositions (ps of the polystyrene block in SI and total molecular weights was investigated on the solution-cast film with toluene as a neutrally good solvent. In the range of the composition f PS =0.35-0.69 covered, the two SI copolymers were found to be totally miscible on the molecular level at all compositions, forming a single microdomain morphology, if their molecular weight ratio is smaller than about 5. They were found to be only partially miscible, if their molecular weight ratio is greater than about 10, forming macroscopically phase-separated coexisting labellar microdomains with different domain spacings

Miscibility and cocrystallization in homopolymer-segmented block copolymer blends

The amorphous phase behavior of blends of poly(butylene terephthalate) (PBT) and poly(ester-ether) segmented block copolymers (PEE) was found to vary from completely immiscible to miscible, depending on the copolymer composition. The predictions of the Flory-Huggins relationship are in general agreement with the observed behavior when the interaction parameters are estimated from solubility parameters. The results of thermal analysis and small-angle X-ray scattering experiments strongly suggest that the PBT and PEE copolymers are capable of cocrystallization in the miscible blends under all crystallization conditions. The cocrystalline microstructure results from the complete miscibility and the blocky nature of the copolymer (i.e., the identical chemical and crystalline structures of the PEE hard segments and PBT). The crystallization rate of the copolymer in the miscible blends was found to be significantly enhanced due to the presence of PBT, and the resulting crystal thickness was found to be the same as that observed for PBT. Partially miscible blends of PBT with copolymers containing intermediate hard-segment concentrations formed distinguishable crystal populations, but the crystallization rate of the copolymer in these blends was also strongly influenced by the presence of PBT.

The Compatibility and Crystallization of the Mixtures of Poly (Tetrahydrofuran-b-methyl methacrylate) Diblock Copolymer with Polyvinyl Chloride Homopolymer

The compatibility and crystallization behaviour of the mixtures of poly (tetrahydrofuran-methyl methacrylate) diblock copolymer (PTHF-b-PMMA) with polyvinyl chloride has been studied. We found that the compatibility of these blends, in which there is special interaction between the homopolymer and the PMMA block of the copolymer, is much better than that of the AB/A type blends; and that the crystallization rate and crystallinity of PTHF microdomain changed greatly due to the swollen by PVC homopolymer. In this paper, these changes in cryatallization are well explained according to the theories of block copolymer blends and the density gradient model presented by JIANG Ming.

Miscibility and crystallization kinetics in blends of poly(ethylene terephtalate) and thermotropic liquid crystal polyesters

AbstractBinary blends of poly(ethylene terephtalate) (PET) and thermotropic liquid crystal polyester (TLCP) have been prepared by both solution and melt blending methods. The TLCPs utilized were Vectra (Hoechst Celanese), TR‐4, a TLCP synthesized in our laboratory, and a block copolymer consisting of three TR‐4 units followed by three PET units. The phase behavior of the blends was studied by differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA) and optical microscopy. The results show that none of the blends is miscible, but significant interactions exist between the PET phase and the TLCP phase in the case of TR‐4 and TR‐4 block copolymer blends. These interactions lead to a different nucleation mechanism in these blends compared to that in PET/Vectra.

Molecular-weight factors affecting formation of the OBBD morphology in block copolymer blends

Microphase-separated diblock copolymers have been known since 1970 to exhibit three principal morphologies. These morphologies depend on the composition of the copolymer and include dispersed spheres of the minor component on either a BCC or FCC lattice, dispersed cylinders of the minor component on a hexagonal lattice, or alternating lamellae. Recent microstructural studies of starblock and diblock copolymers have shown that an ordered bicontinuous morphology is observed between the lamellar and cylindrical regimes. This microstructure is currently referred to as the ordered bicontinuous double-diamond (OBDD) morphology and is an example of the Pn3m space group. In poly(styrene-b-isoprene) (SI) diblock copolymers, it exists at approximately 62-66 vol% polystyrene (PS). Efforts aimed at producing this morphology by blending a copolymer with various PS homopolymers have also been successful, when the blend composition is 65-67 vol% PS and the molecular weight of the hompolymer (Mhps) is less than that of the styrene block in the copolymer (Ms). In this work, we have used transmission electron microscopy to elucidate some additional factors responsible for development of the OBDD and other bicontinuous morphologies.

Self-consistent theory of block copolymer blends: selective solvent

A theoretical study of the lamellar microphase of block copolymer/selective solvent blends in which the solvent is good for one block and either good or near-θ for the other is presented. The calculations used numerical solutions to the equations of the self-consistent mean-field theory of polymer blends. Two types of systems were studied. In the first, all pure-component densities were taken to be equal, as were the two Kuhn statistical lengths, and the solvent was idealized as being athermal for one of the blocks. In the other type, realistic values for these parameters were used.

Morphology and Mechanical Properties of Blends of Styrene-butadiene Block Copolymer with Methyl Methacrylate-styrene Copolymer

Polymer blends of a styrene-butadiene block copolymer (SBS) with a methyl methacrylate-styrene copolymer (MS) were prepared by extrusion and the morphology of the extrudates was observed. These extrudates were injection and compression molded, and the resultant morphology and mechanical properties of the moldings were also examined. In all cases the SBS phase of SBS/MS blends formed lamellar structure in which the polybutadiene (PB) phase and the polystyrene (PS) phase showed alternate layers with thicknesses of 150∼200A and 200∼250A, respectively. Such lamellae strictly consisted of quasi-layers in which the PB dispersed phase in large aspect ratio was surrounded by the PS matrix. Compression molded blends showed higher order than injection molded blends, which suggests that lamellae in the former were relaxed on slow cooling to neat stratification. The MS particles in extrudates were highly oriented because of the extensional flow field which occurred in the melt strands after exiting from the die on extrusion. Such flow-induced orientation was well relaxed after compression molding. Compression molded blends including 10 to 40wt.% MS, showed excellent notched Izod impact strength, but were inferior to the corresponding injection molded blends in tensile and flexural properties and deflection temperature under flexural load. Compression molded blends showed good impact energy dissipation, since the highly ordered lamellae were deformed with extensive shear yielding developement and the neat MS particles were debonded from the SBS matrix on fracture. The improved tensile and flexural properties of the injection molded blends would be due to the smaller aspect ratio of the PB dispersed phase leading to a closer network of the rigid PS phase in the quasi-layers of the SBS lamellae.

Theory of microphase formation in reversibly associating block copolymer blends

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTTheory of microphase formation in reversibly associating block copolymer blendsFumihiko Tanaka, Masahiko Ishida, and Akihiko MatsuyamaCite this: Macromolecules 1991, 24, 20, 5582–5589Publication Date (Print):September 1, 1991Publication History Published online1 May 2002Published inissue 1 September 1991https://doi.org/10.1021/ma00020a016RIGHTS & PERMISSIONSArticle Views238Altmetric-Citations51LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (855 KB) Get e-AlertsSupporting Info (1)»Supporting Information Supporting Information Get e-Alerts

Functional polypropylene blend compatibilizers

AbstractSolid phase dispersants, often referred to as blend compatibilizers, are the key components of high‐value‐in‐use polypropylene blends with unusual property combinations. In multiphase polypropylene blends, functional blend compatibilizers enhance the dispersion of incompatible polymeric blend components, in particular of polar polymers, fibers or fillers, and improve the interfacial adhesion between polymer matrix and dispersed phases. Some of the major synthetic routes to functional polypropylene blend compatibilizers are discussed. A novel range of monofunctional polypropylenes containing a variety of functional endgroups, e.g., anhydrides, esters, amines, carboxylic acids, silanes, boranes, alcohols, and thiols, has been derived from mono‐olefin‐terminated polypropylenes. These olefinic polypropylene intermediates have been prepared with soluble metallocene catalysts which give excellent control of polypropylene molecular weight, molecular weight distribution, microstructure, and olefinic endgroups. Thiol‐terminated isotactic polypropylenes have been used as polymeric chain transfer agents in styrene and styrene/acrylonitrile polymerization to form novel polypropylene‐block‐polystyrene and polypropylene‐block‐poly(styrene‐co‐acrylonitrile) block copolymers. In the case of poly(styrene‐co‐acrylonitrile) blends with polypropylene morphological studies demonstrate the efficiency of propylene block copolymer blend compatibilizers.

Microphase and macrophase separation in blends with a two-block copolymer

The miscibility behaviour of blends A αβ of a homopolymer A and a symmetric two-block copolymer αβ, where the chains A and the blocks α are chemically the same and immiscible with the blocks β, is analysed theoretically and experimentally. The blends are compared with corresponding blends A αβ′ , where the copolymer αβ′ is random. The styrene (S)/methyl methacrylate (MMA) model systems investigated consist of a copolymer P(S- b-MMA) (two-block) or P(S- co-MMA) (random) and a homopolymer PMMA of varying chain length. The process of phase separation during film casting at different temperatures was analysed by mean-field calculations, and the morphologies of the cast films were studied by transmission electron microscopy. The block copolymer blends exhibit both microphase and macrophase separation, which develop in two steps in the order microphase-macrophase or macrophase-microphase. Which sequence is preferred can be predicted from the homopolymer-copolymer chain-length ratio.

Phase separation in binary block copolymer blends

The well defined poly(styrene(S)-b-isoprene(I)) and poly(S-b-2-vinylpyridine(2VP)) diblock copolymers were prepared by sequential anionic addition. Binary poly(S-b-I)/poly(S-b-2VP) diblock copolymer blend films were prepared by solution casting, varying the volume fraction of the three-block sequences. Morphological results were obtained by transmission and scanning electron microscopy (TEM and SEM). The three-phase separated microdomains formed depended strongly on the volume fraction of binary block sequences and casting conditions.

Combined small-angle neutron scattering-small angle x-ray scattering study of blends of styrene-butadiene block copolymer with deuterated polybutadiene

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCombined small-angle neutron scattering-small angle x-ray scattering study of blends of styrene-butadiene block copolymer with deuterated polybutadieneShuichi Nojima, Ryong Joon Roe, David Rigby, and C. C. HanCite this: Macromolecules 1990, 23, 19, 4305–4312Publication Date (Print):September 1, 1990Publication History Published online1 May 2002Published inissue 1 September 1990https://doi.org/10.1021/ma00221a018RIGHTS & PERMISSIONSArticle Views192Altmetric-Citations15LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (877 KB) Get e-Alerts Get e-Alerts

Self-consistent theory of block copolymer blends: Neutral solvent

We present a theoretical study of the lamellar structure of diblock copolymers blended with neutral solvent. The calculations are based on numerical solutions of the equations of the mean field self-consistent theory of incompressible polymer/solvent blends, from the weak through to the strong segregation limits. For idealized model systems of symmetric copolymers and perfectly nonselective solvent, we examine the variation of the equilibrium lamellar thickness with molecular weight, Flory χ parameter, solvent quality, and copolymer volume fraction, as well as the distribution of solvent and polymer within the subdomains. We also examine a real system which has been extensively studied experimentally, namely PS-b-PI with the (nearly) nonselective solvent toluene.

Studies on rheological and mechanical properties of isotactic polypropylene‐olefine/styrene block copolymer blends

AbstractExperimental studies of the blends consisting of isotactic polypropylene and olefine/styrene block copolymers have been carried out. Measurements of viscoelastic and mechanical properties as well as electron microscope observations have shown that the above system has a biphasic structure within the whole composition range. Olefine/styrene block copolymer is a good agent for polypropylene toughening, as the impact strength is increased by several hundred percent especially at low temperatures.

Self-blunting of notches in films of polycarbonate-polyarylatearylene sulphonoxide block copolymer blends

Films of polycarbonate-polyarylatearylene sulphonoxide block copolymer blends underwent stretching, the samples each having a sharp notch. Stretching of the samples with a definite make-up of the blends showed that the rupture stress increases with the increase in the notch length. This was explained with the aid of a model of crack self-blunting by plastic deformation. The degree of self-dulling increases with the growth in the forced elasticity stress.

A scheme to predict the morphology of diblock copolymers and their blends

AbstractDiblock copolymers of α‐methylstyrene and isoprene were synthesized anionically. The morphology of the copolymers and of their blends with the homopolymers was studied by transmission electron microscopy. Based on this, a scheme is proposed to predict the morphological behavior associated with the blending of block copolymers with homopolymers. Two blending systems are discussed. They are (i) copolymer AB with homopolymers A and B and (ii) copolymers AB of two different molecular weights with homopolymer A. Two factors are considered to be the most crucial. One is the morphology of the predominant polymer (50 wt %), and the other is the weight ratio of the blends. The solubilizing effect of the block copolymer AB in the blend must also be taken into account. When the two copolymers are blended, the one with lower molecular weight was emulsified by higher one and restricted around the longer chain. It is shown that the present scheme is successful in predicting the morphology of diblock copolymers and their blends.

Toughness of two pure block copolymer blends in high molecular weight polystyrene

Blends of two commercial pure block copolymers, Phillips KRO-1 and KRO-3 Resins, in high molecular weight PS were prepared by solvent casting techniques to produce composite spherical particles with two different morphologies in a majority phase of the high molecular weight PS. One type of particle had the typical KRO-1 Resin morphology of randomly wavy and often interconnected PB rods in a topologically continuous block copolymer phase of PS, while the other type of particle made of KRO-3 Resin was in the form of concentric shells of alternating layers of PB and PS block copolymer phases. Both blends were found to result in only a marginal improvement of the toughness of homo PS even for particle volume fractions as high as 0.22. This inadequate performance in the case of the KRO-1 Resin blends results from the relatively large stiffness of the KRO-1 particles, while in the case of the KRO-3 Resin blend, it results from too small an average particle size, even though the particle stiffness in the latter case is low.

Craze plasticity and toughness of particulate block copolymer blends

Blends of KRO-1 Resin in high molecular weight polystyrene in which the K-Resin appears as dispersed spherical composite particles with the characteristic K-Resin morphology have been modified by incorporating into them additional polybutadiene of a molecular weight of 3 kg/mole (PB3K). It was found that small additions of PB3K into KRO-1 initiate first a morphological transformation resulting in particles with two coexisting morphologies of distorted rods and parallel lamellae. At a ratio of PB3K/KRO-1 of somewhat above 0.33 the transformation is complete and results in composite particles with a very regular concentric spherical shell morphology of PB and PS. The craze initiating effectiveness of composite particles peaks with this morphology, resulting in craze flow stresses as low as 8 MPa and strains to fracture in excess of 0.80 for a PB3K/KRO-1 ratio of 0.5. Larger volume concentrations of PB3K result in reprecipitation of free PB3K inside particles and this gives rise to a rapid degradation of toughness. The very effective craze initiating action of the spherical shell particles cannot be fully accounted for by the best techniques of numerical stress analysis of the elastic and thermal properties of the composite particles utilizing locally multiaxial craze initiation criteria that were developed for surface crazing in homo-PS. It is suspected that the craze initiation condition is locally relaxed around such composite particles by the presence of certain pre-existing ‘catalytic’ interface configurations that makes the nucleation of crazes from such particle interfaces more a heterogeneous nucleation phenomenon than a homogeneous nucleation phenomenon.