Styrene-isoprene Diblock Copolymer Research Articles

Dielectric relaxation of styrene-isoprene diblock copolymer solutions: a common solvent system

Dielectric relaxation of styrene-isoprene diblock copolymer solutions: a common solvent system

Stability of the chain structure of a styrene–isoprene diblock copolymer during the hydrogenation by diimide

AbstractOlefinic double bounds of a model styrene–isoprene diblock copolymer were hydrogenated using diimide (generated by a thermal decomposition of p‐toluenesulfonyl hydrazide). The presence of byproducts and/or main‐chain structural alterations (e.g., degradation or cross‐linking), as a possible side effect of this polymer analogous reaction, was checked by NMR spectroscopy, elemental analysis, static and dynamic light scattering, and GPC. A twofold concentration of Irganox 1010 antioxidant in the reaction mixture (as compared to the original reported procedure) seems to inhibit the formation of byproducts as well as to prevent any alterations on the macromolecular level. No reactions of isoprene monomer units (other than the addition of hydrogen atoms) and no changes in molar‐mass distribution of the substrate were detected by the methods used.

Dynamic light scattering from microstructured block copolymer solutions

Solutions of a nearly symetric styrene-isoprene diblock copolymer in toluene were studied by dynamic light scattering at compositions above and below the order-disorder transition. In all cases the scattered intensity autocorrelation function exhibits two distinct modes. The faster one is attributed to the translational diffusion of the copolymer, the slower one to cooperative rearrangements of microdomains.

Dielectric relaxation of styrene-isoprene diblock copolymer solutions: a selective solvent system

For solutions of diblock polystyrene-cis-polyisoprene (poly-SI) in toluene, strong influences of the microphase separation on the dielectric normalf-mode relaxation of the I-blocks involved were found. In microphase-separated poly-SI solutions at high concentrations and/or low temperature, the I-blocks exhibit broad double-peaked e curves. In such solutions, the S-phase diluted with toluene is liquid and the S-I junction points are movable. The high-f mode of the polySI solution is attributable to the fluctuation of such junctions in the S-I interphase, and the low-f mode to the fluctuation of the free I-ends

Dielectric relaxation behavior of styrene-isoprene diblock copolymers: bulk systems

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTDielectric relaxation behavior of styrene-isoprene diblock copolymers: bulk systemsMing Long Yao, Hiroshi Watanabe, Keiichiro Adachi, and Tadao KotakaCite this: Macromolecules 1991, 24, 10, 2955–2962Publication Date (Print):May 1, 1991Publication History Published online1 May 2002Published inissue 1 May 1991https://doi.org/10.1021/ma00010a049RIGHTS & PERMISSIONSArticle Views280Altmetric-Citations60LEARN 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 (919 KB) Get e-Alerts Get e-Alerts

Structure of The Diblock Co-Polywer Aggregates in Solution

AbstractWe have employed a variety of scattering techniques to study the structure of diblock copolymer aggregates in solution The system of interest is an anionically prepared poly(styrene-isoprene) diblock copolymer (PS-PI) with well defined molecular weight and composition. When the diblock copolymer is added to decane, which dissolves the polyisoprene but not the polystyrene, we observe that polymeric micelles form at concentrations above a critical micellar concentration. The aggregation number is determined by light scattering and neutron scattering to be roughly 120. The micellar aggregate consists of a spherical polystyrene core with a mean radius of 105 A surrounded by a PI corona. The size distribution is quite narrow (<10%). The PS core is swollen with the solvent by roughly a factor of 2 in volume. By combining dynamic light scattering and SANS, we determined the thickness of the corona to be 50 A, which is 70% larger than the radius of gyration of a free PI chain of the same molecular weight in a good solvent. Furthermore, SANS measurements suggest that the aggregates form an ordered phase at the nominal cross-over concentration as it is expected for a highly functionalized star-branched macromolecules in solution.

Motional perturbation at the microphase boundary in thermoplastic elastomers

The effect of the microdomain boundary upon the dynamics of the polyisoprene chains in studied using solid state 13 C NMR in styrene-isoprene diblock copolymers having a lamellar morphology

Fluorescence energy-transfer studies of bulk styrene-isoprene diblock copolymers and their blends with polyisoprene: applications to microphase separation

Fluorescence energy-transfer studies of bulk styrene-isoprene diblock copolymers and their blends with polyisoprene: applications to microphase separation

Application of the random phase approximation to styrene-isoprene diblock copolymers in solution

Application of the random phase approximation to styrene-isoprene diblock copolymers in solution

The Ordered Bicontinuous Double Diamond Structure in Binary Blends of Diblock Copolymer and Homopolymer.

ABSTRACTWe report the observation of the ordered bicontinuous double diamond (OBDD) structure in binary blends of poly(styrene-isoprene) diblock copolymer and homopolystyrene. The overall polystyrene volume fraction range is 64 - 67 PSvol% for the OBDD structure in binary blends of a lamellar diblock (SI 27/22) and a homopolymer (14.0 hPS). This composition range is approximately within the polystyrene volume fraction range established for pure diblock copolymers in the strong segregation regime having the OBDD structure. Ordered lamellae are observed at approximately 65 PSvol% when the homopolystyrene molecular weight is greater than the molecular weight of the polystyrene block of the copolymer. This observation is discussed in terms of the decreased degree of mixing between the homopolymer and the corresponding block and the resultant effect on the interfacial curvature.

Dynamic IR Studies of Microdomain Interphases of Isotope-Labeled Block Copolymers

ABSTRACTBy probing the localized segmental motion of isotope-labeled block copolymers, the physical nature of the interphase region between microphaseseparated domains of block polymers was examined. Dynamic infrared linear dichroism (DIRLD) spectroscopy, which measures the reorientations of submolecular structures induced by a small-amplitude oscillatory strain, was combined with specific isotope-labeling using deuterium-substituted monomers. The latter technique enabled us to differentiate the dynamic responses of well-defined parts of block segments, e.g., near the segment junction, chain end, or middle of the block. The degree of segmental interactions near the interphase region of styrene-isoprene diblock copolymers were studied as a function of the segment location and temperature. The reorientational motion of the polystyrene segment, especially near the block junction, was monitored around the glass transition temperature of the polyisoprene matrix. From this result, the degree of segmental mixing in the interphase region which leads to local plasticization of the polystyrene segment was determined.

A verage lamellar domain distance in microphase-sepa-ration structure for the system of polystyrene, polyisoprene and styrene-isoprene diblock copolymer.

A verage lamellar domain distance in microphase-sepa-ration structure for the system of polystyrene, polyisoprene and styrene-isoprene diblock copolymer.

Phase-separation structure of polymer blend of polystyrene and polyisoprene in the presence of styrene-isoprene diblock copolymer.

The micro-phase-separation structure of a system of homopolymers and a block copolymer was investigated theoretically and experimentally. Phase-separation experiments were carried out for the blend system of homopolystyrene and homopolyisoprene in the presence of styrene-isoprene diblock copolymer, employing solvent casting as the method for the formation of phase separation. The experimental results revealed a lamellar structure in the micro-phase-separation, and domain spacings of the structure were measured. A model for the lamellar structure of copolymer/homopolymer systems is proposed to predict the domain spacing on the basis of the statistical thermodynamic theory of Whitmore and Noolandi. The model can predict the domain spacing well in most cases.

Synthesis and Characterization of Styrene-Isoprene Diblock Copolymers

Abstract A simple reusable apparatus for the synthesis of up to 40 g quantities of poly(styrene-b-isoprene) diblock copolymers of reasonably low (1.2 to 1.5) polydispersity has been described. The diblock copolymers synthesized were characterized by gel permeation chromatography (GPC), membrane osmometry, viscosimetry, and nuclear magnetic resonance (NMR) spectroscopy. Number-average molecular weights (M n) calculated from the raw GPC chromatographs of the diblock copolymers using the summation method and M versus elution volume plots for polystyrene and polyisoprene standards agree well with those measured experimentally with osmometry. It is suggested that for polydisperse block copolymers this method is simpler than the use of a universal calibration curve. Mark-Houwink constants K ans a for polyisoprene having 18% (1,2-), 66% (3,4-), and 16% (1,4-) microstructure were found to be 3.2 × 10−4 dL/g and 0.67, respectively, in THF at 25°C. In toluene at 30°C, K = 2.0 × 10−4 dL/g and α = 0.7 were obtained. The diblock copolymers had 26% (1,2-), 60% (3,4-), and 14% (1,4-) microstructure in the isoprene segments, and the values of K and a for these copolymers (PS > 50%, M 20.0 × 103) in THF at 25°C were 9.0 × 10−5 dL/g and 0.75. For M < 20.0 × 103 the value of α was 0.5. The experimental values of [η] were found to be lower than those calculated theoretically, presumably due to the polydisperse nature and the biellipsoidal configuration of the diblock copolymers.

Microphase Separation in Low Molecular Weight Styrene-Isoprene Diblock Copolymers Studied by DSC and 13C NMR

Microphase Separation in Low Molecular Weight Styrene-Isoprene Diblock Copolymers Studied by DSC and ¹³C NMR