Block copolymers with low surface energy segments: siloxane- and perfluoroalkane-modified blocks
TL;DR: In this article, the authors describe the preparation and preliminary characterization of diblock copolymers with a low surface energy block, which were prepared by modifying the isoprene block in styrene-isoprene-based block copolymer with either short perfluoroalkyl or dimethyl siloxy "fingers".
Abstract: In this paper we describe the preparation and preliminary characterization of diblock copolymers with a low surface energy block. These polymers were prepared by modifying the isoprene block in styreneisoprene-based block copolymers with either short perfluoroalkyl or dimethyl siloxy ‘fingers’. Specifically, the diene block of a styrene-isoprene block copolymer containing a large proportion of pendent vinyl groups (1,2- and 3,4-isoprene) was reacted with the appropriate hydrosilane in the presence of non-acidic Pt catalyst. The degree of attachment of hydrosilane was as high as 50% of the pendent unsaturations. Pendent vinyl groups were converted more efficiently than pendent methyl vinyl groups. These block copolymers, when mixed with the styrene homopolymer, exhibited surface segregation behaviour which depended on both polymer molecular weight and processing conditions. The surface segregation properties of the resulting block copolymers were studied by a variety of techniques which include contact angle measurements, and either X-ray photoelectron spectroscopy or Rutherford backscattering spectrometry. Contact angles as high as 110° were measured for both the siloxane- and perfluoroalkane-modified materials.
TL;DR: In this article, a block copolymer was synthesized by anionic polymerization of poly(styrene-b-1,2/3,4-isoprene) followed by corresponding polymer analogous reactions, and the effect of chemical structure on surface properties and the influence of liquid crystalline structure of the semifluorinated side chain on the surface behavior were evaluated.
Abstract: Monodisperse poly(styrene-b-semifluorinated side chain) block copolymers were synthesized by anionic polymerization of poly(styrene-b-1,2/3,4-isoprene) followed by the corresponding polymer analogous reactions. By controlling the block copolymer composition and the relative lengths of the fluorocarbon and hydrocarbon units in the side group, the effect of chemical structure on surface properties and the influence of liquid crystalline structure of the semifluorinated side chain on the surface behavior were evaluated. The composition of side groups does not greatly affect the as-prepared sample surface tension, but influences instead the transition temperatures of the room temperature liquid crystal phase. It was observed that the shorter fluorocarbon units (six −CF2− units) form a smectic A phase at room temperature. The critical surface tension of the SA phase is 10.8 mN/m, and the polymer surface undergoes significant reconstruction when immersed in water. However, when the fluorocarbon side chain conta...
TL;DR: In this article, a diblock copolymer of deuterated styrene and isoprene was chemically modified to incorporate pendant fluorinated side chains (fingers) by forward recoil spectrometry, and surface segregation and interfacial segregation of the modified block copolymers from a polystyrene matrix were observed in as-spun films.
Abstract: A diblock copolymer of deuterated styrene and isoprene (dPS−PI) with a small volume fraction of isoprene was chemically modified to incorporate pendant fluorinated side chains (“fingers”). The composition distribution of the diblock copolymers within a high molecular weight polystyrene (PS) homopolymer was determined by forward recoil spectrometry. Surface segregation and interfacial segregation of the modified block copolymers from a polystyrene matrix are observed in as-spun films. Equilibrium segregation was achieved on annealing at 160 °C for several days. The segregation isotherms at the air−polymer interface are shown to be quantitatively described by a self-consistent mean field theory (SCMF), and these permit us to estimate an effective Flory parameter which describes the attraction of the fluorinated segments to the surface and their repulsion from the bulk. The change in the surface tension as a result of the adsorption of the block copolymers at the air−homopolymer interface was evaluated from ...
TL;DR: The block copolymers in this article have been designed to have nearly identical molecular weight azobenzene-containing LC blocks in order to eliminate possible variations in LC behavior caused by the differences in the LC block molecular weight.
Abstract: The synthesis and characterization of a family of well-defined liquid crystal−coil (LC−coil) diblock copolymers have been carried out. The block copolymers in this study have been designed to have nearly identical molecular weight azobenzene-containing LC blocks in order to eliminate possible variations in LC behavior caused by the differences in the LC block molecular weight. Quantitative hydroboration chemistry was used to convert the pendent double bonds of an isoprene block to hydroxyl groups to which the mesogenic groups were attached via acid chloride coupling. The LC homopolymer and the block copolymers (LC volume fraction from fLC = 0.82 to fLC = 0.20) all exhibited smectic mesophases with similar clearing transition temperatures. The clearing transition enthalpies strongly depend on the block composition ratio and decrease as the LC block volume fraction decreases. Solvent-casting of a lamellar LC−coil copolymer (SICN5-66/60) resulted in an oriented bulk film in which both the axes of the mesogen...
TL;DR: In this paper, a review of methods for the bulk incorporation of fluorine in or along the backbone of macromolecules with fluorination procedures adhering to these criteria is presented.
Abstract: Polymers that contain atomic fluorine in or along the backbone possess many desirable physical properties. In general, fluoropolymers exhibit high thermal stability, enhanced chemical resistance, and low surface energy when compared to their non-fluorinated analogs. Two distinct routes are ordinarily utilized for the synthesis of these interesting macromolecules. Firstly, they can be prepared by the polymerization of fluorine-containing monomers (e.g. polytetrafluoroethylene from tetrafluoroethylene). Secondly, fluoropolymers can be prepared through polymer modification reactions that incorporate fluorine atoms or fluorine-containing moieties into a non-fluorinated parent polymer. Many commercially available fluoropolymers are prepared by the polymerization of fluorinated monomers. However, the different types of fluoropolymers that can be prepared by this route are limited by the availability of unique, suitably reactive fluorine-containing monomers. On the other hand, polymer fluorination methods, while less commonly practiced, allow for the preparation of novel fluorinated materials for which there is no suitable fluorine-containing monomer. Numerous methods have been described for the fluorination of polymers. These methods range from reactions that use fluorinated reagents to degrade or crosslink the polymeric substrate, to reactions that add fluorine atoms to the polymer in a highly non-specific fashion, to methods that introduce fluorine in a very selective manner to specific functional groups present in the parent polymer backbone. In the context of this review, ideal polymer fluorination methods are ones that allow for the selective and controlled introduction of fluorine atoms or fluorine-containing molecules to functional groups in or the polymer backbone without inducing degradation or crosslinking of the parent polymer chains. This article reviews methods for the bulk incorporation of fluorine in or along the backbone of macromolecules with fluorination procedures adhering to these criteria.
TL;DR: In this paper, the synthesis of perfluorinated and semi-fluorinated (FL) homopolymers is discussed, and the surface, solution, and bulk properties of polymer structures including FL units reflect these characteristics of the self-organization of polymers with FL components.
Abstract: This article reviews the synthesis by methodologies based on living/controlled polymerization, of well-defined perfluorinated and semifluorinated (FL) homopolymers, chain-end-functionalized polymers with FL group(s), block copolymers having FL segment(s), chain-end-multifunctionalized polymers with a definite number of FL groups, and star-branched and dendrimer-like hyperbranched polymers having FL segment(s). Most of the FL groups and FL segments comprise perfluoroalkyl and/or semifluoroalkyl side chains, represented as a CF3(CF2)m−1(CH2)n moiety. In the FL polymers herein presented, except for FL homopolymers, such FL components are chemically linked to non-FL polymer chains and readily separated at the molecular level, followed by self-organization, to form a variety of nanoscale molecular assemblies at the surface of a film, in bulk, and in solution. The FL components possess many unique and interesting characteristics, such as remarkably low surface energies, low friction coefficients, strong incompatibility with conventional hydrocarbon-based polymers, high thermal stability, chemical inertness, and phenyl-free liquid crystalline formation. The surface, solution, and bulk properties of polymer structures including FL units reflect these characteristics of the self-organization of polymers with FL components is of particular interest. Moreover, non-FL polymer chains may enhance the solubility of FL polymers, and render molecular assemblies more changeable in shape, form, and size. Recent reports on these subjects are presented in this review.
01 Jan 2003
TL;DR: In this article, the authors present a survey of the properties of polymers and their application in the field of chemical engineering, including the following: Coextrusion, Injection Molding, Flexible Packaging, Fibers, Polymer-Clay, and Plasticizers.
Abstract: VOLUME 1. Acetylenic Polymers, Substituted. Acrylamide Polymers. Acrylic (and Methacrylic) Acid Polymers. Acrylic Ester Polymers. Acrylonitrile and Acrylonitrile Polymers. Acrylonitrile-Butadiene-Styrene Polymers. Additives. Adhesion. Adhesive Compounds. Aging, Physical. Alkyd Resins. Am,ino Resins and Plastics. Antifoaming Agents. Atomic Force Microscopy. Biotechnology Applications. Bloack Copolymers. Bloack Copolymers, Ternary Triblock. Blow Molding. Chitin and Chitosan. Chromatography, Affinity. Chromatography, HPLC. Chromatography, Size Exclusion. Coating Methods, Survey. Coatings. VOLUME 2 Coextrusion. Colorants. Coloring Processes. Composites, Fabrication. Conformation and Configuration. Critical Phase Polymerizations. Cyclohexanedimethanol Polyesters. Dendronized Polymers. Dental Applications. Diacethylene and Triacethylene Polymers. Elasticity, Rubber-Like. Electronic Packaging. Electrooptical Applications. Engineering, Thermoplastics, Overview. Enzymatic Polymerization. Ethylene Polymers, Chlorosulfonated. Ethylene Polymers, HDPE. Ethylene Polymers, LDPE. Ehtylene Polymers, LLDPE. Ethylene-Acrylic Elastomers. Ethylene-Norbornene Copolymers. Extrusion. Films, Orientation. Fluorocarbon Elastomers. Fractography. Fracture. Glass Transition. Hardness. Hydrogels. Hyperbranched Polymers. VOLUME 3 Injection Molding. Inorganic Polymers. Laser Light Scattering. Light-Emiting Diodes. Lignin. Liquid Crystalline Polymers, Main-Chain. Liquid Crystalline Thermosets. Mass Spectrometry. Membrane Technology. Methacrylic Ester Polymers. Micromechanical Properties. Modeling of Polymer Processing and Properties. Nanocomposites, Polymer-Clay. Packaging, Flexible. Perfluorinated Polymers, Perfluorinated Ethylene-Propylene Copolymers. Perfluorinated Polymers Polytetrafluoroethylene. Perfluorinated Polymers Tetrafluoroethylene-Ethylene Copolymers. Perfluorinated Polymers, Tetrafluoroethylene-Perfluorinated Copolymers. Perfluorinated Polymers. Tetrafluoroethylene-Perfluorovinyl Ether Copolymers. Phosgene. Phosphorus-Containing Polymers and Oligomers. Piezoelectric Polymers. Plasticizers. Poly(3-Hydroxyalkanoates). Poly(Trimethylene Terephthalate). Polyamides, Atomatic. Polyamides, Fibers. Polyamides, Plastics. Polycyanoacrylates. Polyesters, Fibers. Polyketones. Polynucleotides. Polysulfides. VOLUME 4 Polysulfones. Polyurethanes. Pressure-Sensitive Adhesive. Reinforcement. Release Agents. Shape-Memory Polymers. Single-Site Catalysis. Stabilization. Styrene-Butadiene Rubber (SBR). Styrene Polymers. Sulfur-Containing Polymers. Surface Properties. Syndiotactic Polystyrene. Vinyl Fluoride Polymers (PVF). Vinylidene Chloride Polymers. Vinylidene Fluoride Polymers. Viscoelasticity. Weathering.
TL;DR: Copolymere styrene-isoprene as discussed by the authors is an arrangement tetraedrique de courts bâtonnets de polystyrene, and the unites sont interconnectees sur un reseau cubique de groupe spatial Pn3m
Abstract: Copolymere styrene-isoprene. L'unite de base de cette structure est un arrangement tetraedrique de courts bâtonnets de polystyrene. De telles unites sont interconnectees sur un reseau cubique de groupe spatial Pn3m
TL;DR: A morphologie des polymeres coules a partir de solution dans le toluene, depend de la composition du copolymere mais peu de sa masse moleculaire as discussed by the authors.
Abstract: La morphologie des polymeres coules a partir de solution dans le toluene, depend de la composition du copolymere mais peu de sa masse moleculaire
TL;DR: In this article, the segregation de copolymeres bisequences styrene deuterie/2-vinyl pyridine a l'interface de melanges immiscible polystyrene/poly (2Vyl Pyridine) is discussed.
Abstract: La segregation de copolymeres bisequences styrene deuterie/2-vinyl pyridine a l'interface de melanges immiscibles polystyrene/poly (2-vinyl pyridine) est etudiee par FRES et comparee aux predictions d'une theorie a champ moyen dont le parametre essentiel est le potentiel chimique du copolymere