A challenge to novel fluoropolymers

Perfluoro(vinyl ether) derivatives are extremely versatile monomers in preparing a variety of functional fluoropolymers. In this paper, two challenging topics in the development of novel fluoropolymers will be introduced. Carboxylated perfluoro(vinyl ether) can be copolymerized with tetrafluoroethylene to afford perfluorinated ion-exchange membranes, which realize the innovative process for pollution-free and energy-saving chlor-alkali production. Another topic includes the discovery of selective cyclo-polymerization of specially designed difunctional perfluoromonomers such as perfluoro(allyl vinyl ether) which is readily derived from the carboxylated perfluoro(vinyl ether). The novel perfluoropolymer with a cyclic structure in the main chain is characterized by an exceptional transparency, and has been commercialized with expectation of major applications in electronics industries.     

The Application of Controlled/Living Radical Polymerization in Modification of PVDF-based Fluoropolymer

Fluorinated polymers are important materials that are widely used in many areas as taking the advantage of inertness to chemical corrosion, prominent weather resistance, low flammability, and good thermal stability. Poly(vinylidene fluoride)(PVDF) based fluoropolymers is the most common type of commercial fluoropolymer especially used as dielectric materials. However, there are always some shortcomings in practical applications, so it is necessary to modify PVDF-based fluoropolymers for better application. Controlled/living radical polymerization(CRP) and related techniques have become a powerful approach to tailoring the chemical and physical properties of materials and have given rise to great advances in modification of PVDF-based fluoropolymers.     

有机氟材料的结构与性能及其在涂料中的应用

高性能、低（无）污染是当今涂料发展的主要趋势，氟树脂独特的结构特点使它具有很高的耐热性，耐化学性和耐候性，独特的电学性能，优良的表面性能和光学特性，从而使其成为可能同时具有这两项要求的材料之一，本文着重介绍了目前几种最主要的氟树脂的结构与性能，如聚四氟乙烯（PTFT），聚偏二氟乙烯（PVDF）、氟烯烃／乙烯基醚共聚树脂（FEVE）及全氟聚醚 （PFPE）等。另外还对当前国内，外含氟高聚物在涂料应用上的研究进展作了一些介绍。     

gem-Heteroatom-Substituted Fluoroalkenes as Mimics of Amide Derivatives or Phosphates: A Comprehensive Review

gem-Heteroatom-substituted fluoroalkenes have received little attention despite their great potential in medicinal chemistry or in fine chemistry. Indeed, due to the electronic and steric similarity between the fluoroalkene moiety and the amide bond as well as the high strength of the carbon-fluorine bond, these gem-heteroatom-substituted fluoroalkenes could be envisioned as stable mimics of various important organic functions, such as phosphates, carbamates, S-thiocarbamates and ureas. We present herein an overview describing the syntheses over the last decade of heteroatom-substituted fluoroalkenes in geminal position. This review will be divided into several sections covering each the common following heteroatom: oxygen-, nitrogen-, sulfur-, phosphorus-, boron- and silicon-substituted fluoroalkenes.     

Pd-catalyzed couplings of (α-fluoro)vinyl tris(trimethylsilyl)germanes

The (α-fluoro)vinyl tris(trimethylsilyl)germanes undergo Pd-catalyzed cross-couplings with aryl and alkenyl halides upon oxidative treatment with hydrogen peroxide under basic aqueous conditions to give access to fluoroalkenes and fluorodienes with retention of stereochemistry.     

Homopolymers and vinyl chloride copolymers of vinyl esters of chlorinated fatty acids from umbelliferae and limnanthes douglasii

Homopolymers and copolymers of vinyl esters of chlorinated C₁₈, C₂₀, and C₂₂ fatty acids with vinyl chloride have been prepared and evaluated. The incorporation of the vinyl ester of chlorinated C₁₈, C₂₀, and C₂₂ acids as comonomers with vinyl chloride produced more flexible copolymers than have other comonomers, yet none have imparted the plasticization that can be obtained by an equal amount of external plasticizer.     

Novel copolymers via nitroxide mediated controlled free radical polymerization of vinyl chloride

Controlled free radical polymerization (CFRP) of vinyl chloride (VCM) and copolymerization with several comonomers have been studied in aqueous suspension. Therefore di-tert-butylnitroxide and three novel nitroxyl radicals were used as mediating agents. Copolymerization of VCM with styrene, partly combined with acrylonitrile, maleic acid anhydride and maleic acid imide as well as methyl methacrylate, n-butyl methacrylate, butyl acrylate and butadiene have been achieved, demonstrating an efficient route for novel vinyl chloride copolymer architecture.     

含氟聚合物(PPFGs)的制备及其构筑疏水棉布的性能研究

采用五氟苯乙烯(PFS)和甲基丙烯酸缩水甘油酯(GMA)为原料,调控PFS和GMA摩尔比例制备了一系列含氟聚合物(PPFGs),利用PPFGs支链末端环氧基团与基体棉布表面羟基发生化学反应来提高棉布的疏水性能及其耐久性能.通过对PPFGs处理棉布的接触角和形态形貌分析测试表明,含氟聚合物PPFG2化学键合处理的棉布不仅...     

1-O-vinyl glycosides via Tebbe olefination, their use as chiral auxiliaries and monomers

A series of anomerically pure 1-O-formyl glycosides 1 was prepared and converted into the corresponding 1-O-vinyl glycosides 2 by Tebbe olefination. The unsubstituted vinyl glycosides were obtained as anomerically pure compounds in good yields, and the method of preparation was compatible with the presence of a variety of functional groups. Remarkably, the anomeric formate group was regioselectively converted into the corresponding olefin in the presence of acetate and benzoate protecting groups. With the perspective to use the 1-O-vinyl glycosides as monomers for the preparation of glycosylated poly(vinyl alcohol) derivatives with controlled tacticity, their scope as chiral auxiliaries for a stereodifferentiation in addition reactions to the olefin function was investigated by using the [2+2] cycloaddition to dichloroketene as a model reaction. In particular, vinyl 2,3,4,6-tetra-O-benzoyl-alpha-d-mannopyranoside (2i) exhibited excellent diastereoselectivity. Finally, the 1-O-vinyl glycosides were successfully subjected to radical homopolymerization in bulk or used as electron-rich comonomers in radical copolymerizations with maleic anhydride, yielding alternating, glycosylated poly(vinyl alcohol-alt-maleic anhydride).     

Organocatalytic copolymerization of mixed type monomers

Triggered by environmental concerns and the rising demands for metal-free polymers in e.g.bio-related and microelectronic applications,studies on organocatalytic polymerization have been launched and developed unprecedentedly during the last 15 years.A wide range of organic molecules are now available in polymer chemists' toolbox to choose from as catalysts for polymerization of (hetero)cyclic and polar vinyl monomers.Apart from the intrinsic merits such as lower toxicity and better solubility compared with (transition) metal catalysts/initiators,organocatalysts have also shown,in many cases,excellence to achieve high polymerization rates and/or good control (selectivity).In addition,particular natures and catalytic/activating mechanisms of organocatalysts have led to new opportunities for rational design and efficient synthesis of macromolecular architectures,i.e.chain structures,topological structures and functionalities.This mini-review is specially themed on pathways to construct copolymer chain structures by organocatalytic copolymerization of mixed type monomers (comonomers bearing different polymerizing moieties) and will be sectioned by different comonomer combinations,including cyclic monoesters of different sizes,cyclic monoesters and lactides,cyclic esters and cyclic carbonates or epoxides,heterocycles and vinyl monomers.     

Organocatalyzed Photo-Controlled Synthesis of Ultrahigh-Molecular-Weight Fluorinated Alternating Copolymers

Ultrahigh-molecular-weight (UHMW) polymers with tailored structures are highly desirable for the outstanding properties. In this work, we developed a novel photoorganocatalyzed controlled radical alternating copolymerizations of fluoroalkyl maleimide and diverse vinyl comonomers, enabling efficient preparation of fluorinated copolymers of predetermined UHMWs and well-defined structures at high conversions. Versatility of this method was demonstrated by expanding to controlled terpolymerization, which allows facial access toward fluorinated terpolymers of UHMWs and functional pendants. The obtained copolymers exhibited attractive physical properties and furnished thermoplastic, anticorrosive and (super)hydrophobic attributes as coatings on different substrates. Molecular simulations provided insights into the coating morphology, which unveiled a fluorous protective layer on the top surface with polar groups attached to the bottom substrate, resulting in good adhesion and hydrophobicity, simultaneously. This synthetic method and customized copolymers shed light on the design of high-performance coatings by macromolecular engineering.     

Dispersion copolymerization of styrene and other vinyl monomers in polar solvents

Dispersion polymerization is a very attractive method for preparing micrometer‐size monodisperse polymer particles. The applications of microspheres have been greatly expanded by the use of copolymers. Here, the dispersion copolymerization of styrene and seven other vinyl monomers was carried out in polar solvents. The effect of the different comonomers on the particle size was systematically investigated. The particle size first decreased and then increased with an increasing fraction of acrylamide in the monomer feed, and at a higher fraction of such a comonomer, only a gel‐like polymer was obtained. The particle size also increased with the increase in the contents of the hydrophilic comonomers in the monomer mixtures, and the copolymer molecular weight decreased meanwhile. Although the amount of the hydrophobic comonomer in the monomer mixture changed, the particle size was hardly affected. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 555–561, 2001     

Polystyrene with Pendant Mixed Functional Ruthenium(II)‐Terpyridine Complexes

A vinyl substituted 2,2′:6′,2″‐terpyridine and a mixed, bifunctional ruthenium(II)‐terpyridine complex bearing a vinyl and a hydroxymethyl group are utilized as comonomers for radical copolymerization with styrene. The resulting polymers are characterized by means of UV‐vis spectroscopy and gel permeation chromatography, coupled with an in‐line diode array spectrophotometer.     

Specific features of “compensating” copolymerization of butyl acrylate with vinyl butyl ether in the presence of triethylboron

Copolymerization of butyl acrylate with a large excess of boiling vinyl butyl ether was carried out in the presence of triethylborane. The analysis of the composition of the obtained product demonstrated that an alternating low-molecular-weight copolymer was predominantly formed. The formation of macromolecules occurred by both conventional and controlled radical polymerization (CRP), as evidenced by a bimodal molecular weight distribution. As conversion increased, the mode corresponding to the CRP mechanism shifted toward larger molecular masses. The relative activities of comonomers for the process initiated by triethylborane were calculated.     

Pyrolysis of vinyl and vinylidene fluoride polymers: Influence of prior γ-irradiation

Quantitative comparisons were made between the rates of thermal volatilization of several fluoropolymers before and after exposure to γ-radiation. The effects of γ-irradiation on poly(vinyl fluoride) and poly(vinylidene fluoride) were also investigated by swelling and sol-gel ratios. With both polymers as well as with polytrifluoroethylene, crosslinks occur predominantly, though there is an appreciable number of scissions. The rates of volatilization and char formation were enhanced by γ-radiation, whereas the previously studied polytrifluoroethylene did not produce more char upon irradiation, although radiation did accelerate its volatilization. It is believed that in polytrifluoroethylene the enhanced rates of volatilization occur by a different mechanism than in the case of the vinyl and vinylidene fluoride polymers.     

Thermal degradation of vinyl alcohol/vinyl acetate copolymers. III. Study of the reaction products

The thermal decomposition of vinyl alcohol/vinyl acetate copolymers have been studied at p = 10⁻²–10⁻⁴ Torr and T = 0–600°C. The decomposition products (solids, liquids, and gases) have been characterized by infrared (IR) and ultraviolet (UV) spectroscopy, gas chromatography, vapor pressure osmometry, and elemental analysis. It has been ascertained on the basis of the obtained data that the decomposition mechanism of the vinyl alcohol/vinyl acetate copolymers depends on the chemical composition and sequence distribution of comonomers.     

EMULSION COPOLYMERIZATION OF VINYL ACETATE IN PRESENCE OF ACID COMONOMERS

The interaction of acid comonomers, crotonic acid, maleic monoesters, maleic acid with the surfactant, the sodium salt of sulfosuccinic acid semiester with nonyl phenol etoxylated with 25 moles ethylene oxide (NPEO₂₅SS) depends on the hydrophilicity of comonomers. The rate of initiator splitting reaction (potassium persulfate - KPS) in presence of NPEO₂₅SS and of comonomers decreases with the increasing of acid comonomer concentration. This rule is valid in copolymerization of acid comonomers with vinyl acetate (VAc) below a small comonomer concentration, then the rate increases. The presence of some more hydrophobic comonomers maleic diesters, lowers the decomposition rate of KPS. These results are the effect of the stronger interaction of NPEO₂₅SS with more hydrophobic polymer particles. In their presence the concentration of free NPEO₂₅SS is lower and it can participate in the KPS - surfactant reaction and rise its rate to a lesser extent. Owing to some secondary acid comonomer - KPS reactions the productivity of initiator splitting decreases with acid comonomer concentration The glass transition temperatures of the thin films obtained in presence of acid comonomers, may increase or decrease, depending on the volume of the substituents of these comonomers.     

Nuclear magnetic resonance studies on microstructure of ethylene copolymers. VII. Proton resonance spectra of hydrolyzed ethylene–vinyl acetate copolymers1

Complete and partial alcoholyses of ethylene–vinyl acetate (E–VA) copolymers yield ethylene–vinyl alcohol (E–VOH) copolymers and ethylene–vinyl acetate–vinyl alcohol (E–VA–VOH) terpolymers, respectively. From the 220-MHz proton NMR spectra of E–VOH copolymers the stereoregular and chemical sequence distributions of the comonomers can be readily determined. Partially hydrolyzed E–VA polymers were acetylated with perdeuterated acetic anhydride. The monomer distributions in the terpolymers were then quantitatively determined by examining the proton spectra of the derived products. It was found that alcoholysis of E–VA polymers occurs preferentially at VA units which have neighboring VA groups.     

Template-induced control of stereochemistry for the synthesis of linear vinyl polymers

Asymmetric cyclocopolymerization of judiciously designed bifunctional monomers with a number of common comonomers affords optically active vinyl polymers with main chain chirality. Tacticity and sequence of comonomeric units can be controlled and thus complicated structures built up. Under different reaction conditions the same bifunctional monomer 1 can undergo cyclization involving a 19-, a 21-, or an 18-membered ring. With monomer 3 an 11-membered ring is formed.     

Photoorganocatalyzed Divergent Reversible-Deactivation Radical Polymerization towards Linear and Branched Fluoropolymers

Topology influences the properties and applications of polymers. Consequently, considerable efforts have been made to control topological structures. In this work, we have developed a photoorganocatalyzed divergent synthetic approach based on reversible-deactivation radical polymerization (RDRP) that enables the preparation of both linear and branched fluoropolymers of low dispersity (Ð), a tunable degree of branching and high chain-end fidelity by exposure to LED light irradiation under metal-free conditions. This method promotes the generation of complicated structures (e.g., necklace-like and mop-like fluoropolymers) via chain-extension photo-RDRP, and provides a novel and versatile platform to access fluoropolymer electrolytes with high Li-ion transference number and good ionic conductivity, which should create improved opportunities for advanced material engineering.