Polymerization of glycinamide-conjugated monomer alone in concentrated aqueous solution enables facile formation of a mechanically strong and a highly stable supramolecular polymer (SP) hydrogel because of the cooperatively hydrogen-bonded crosslinking and strengthening effect from dual amide motifs. This SP hydrogel exhibits thermoplastic processability, injectability, and self-reparability because of the dynamic destruction and reconstruction of hydrogen bonds in response to temperature change.

A Mechanically Strong, Highly Stable, Thermoplastic, and Self‐Healable Supramolecular Polymer Hydrogel

After an introduction reporting the properties and the applications of fluoropolymers, a first part deals with i) the main routes to produce vinylidene fluoride (VDF) monomer, ii) its homopolymerization, and iii) the advantages and uses of polyvinylidene fluoride (PVDF). In a second section, this review, illustrated by numerous examples, extensively reports the synthesis, properties and applications of the copolymers based on VDF with non-halogenated, fluorinated, commercially available or synthesized comonomers. These comonomers exhibit XYC=CZ-Sp-R structures where X, Y, and Z represent H, F, and CF3 groups, Sp a spacer and R a function such as OH, OAc, SAc, CO2R' (R' being a H atom or an alkyl group), CN, P(O)(OR')2 and SO3H. According to the nature and to the amount of the comonomer, the copolymers can be thermoplastic, elastomeric or thermoplastic elastomers. Introducing reactive R side groups brings complementary properties such as hydrophily, ionic exchange or surface properties, or further crosslinking of the resulting copolymers. Then, the kinetics of radical copolymerization of VDF with M comonomers led to the assessment of the reactivity ratios which are compared. Hence, a reactivity series of these M comonomers with respect to a macroradical terminated by VDF is proposed. Usually, these copolymers exhibit random structures but only three comonomers produced alternating copolymers with VDF: hexafluoroisobutylene, F2C=CFCO2CH3, and H2C=C(CF3)CO2R. The controlled radical copolymerizations of VDF with other comonomers (such as chlorotrifluoroethylene, 3,3,3-trifluoropropene, hexafluoropropylene, perfluoromethyl vinyl ether or-trifluoromethacrylic acid) either in the presence of xanthates, borinates or iodo-compounds are also reported. In addition, new VDF-containing copolymers exhibit well-defined architectures, such as block and graft copolymers. They can be synthesized either by conventional techniques or by controlled radical copolymerization. Chemical modifications of PVDF and poly(VDF-co-monomer) copolymers are also presented. Several properties and applications (such as surfactants, dielectrical polymers, thermoplastic elastomers, fuel cell and ultrafiltration membranes, or polycondensates, the fluorinated segments of which bringing softness and thermal stability) of these VDF-containing copolymers will illustrate this review.

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From vinylidene fluoride (VDF) to the applications of VDF-containing polymers and copolymers: recent developments and future trends.

Most organic polymeric materials melt below 200 °C and most of them begin to degrade rapidly at temperatures only slightly above 200°G. Thermally stable polymers are generally considered to be those which will withstand much higher temperatures without loss of strength or change of structure. In general we expect these materials to withstand at least 300°C in air and up to 500°C or higher in inert atmospheres. Polymers which show these properties are usually highly aromatic in structure, often with heterocyclic units, high melting, sometimes infusible and usually with low solubility in all solvents. This makes their fabrication very difficult and as a consequence limits their usefulness.

Thermally stable polymers

Infrared spectra of polyethylene terephthalate and three of its deuterated analogs have been obtained in the region of 70 to 3600 cm-i, polarized spect,ra having been obtained down to 330 cm-l On the basis of analysis of the predicted spectrum, and with the aid of data from benzene and substituted benzenes, a complete assignment of the spectrum has been made This assignment suggests a modification of the proposed chain structure of this polymer It also leads to the conclusion that the changes in the spectrum which occur upon crystallization of the polymer are not associated with different isomeric forms of the -OCH2CH20portion of the chain, but rather with changes in the symmetry and resonance characteristics of the substituted benzenoid ring framework

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Infrared spectra of high polymers

This review focuses on polymers with upper critical solution temperature (UCST) in water or electrolyte solution and provides a detailed survey of the yet few existing examples. A guide for synthetic chemists for the design of novel UCST polymers is presented and possible handles to tune the phase transition temperature, sharpness of transition, hysteresis, and effectiveness of phase separation are discussed. This review tries to answer the question why polymers with UCST remained largely underrepresented in academic as well as applied research and what requirements have to be fulfilled to make these polymers suitable for the development of smart materials with a positive thermoresponse.

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Polymers with Upper Critical Solution Temperature in Aqueous Solution

Thermally reversible homopolymer gel systems

Microscopic capsules and process for their preparation

Synthetic thermally reversible gel systems. II

In order to study further the effect of structure on monomer reactivities in copolymerization the copolymer composition as a function of initial monomer mixture composition has been determined for the following monomer pairs: vinyl acetate–vinyl chloride, ethyl methacrylate–vinylidene chloride, butyl methacrylate–vinylidene chloride, vinyl acetate–tetrachloroethylene, allyl chloride–vinylidene chloride, vinyl acetate–vinylidenechloride, methyl methacrylate–vinyl chloride, pentene-1–vinyl chloride, allyl chloride–vinyl acetate, methyl methacrylate–2,5-di-chlorostyrene, vinyl chloride–vinylidene chloride, and vinyl chloride–dioctyl maleate.

Howard C. Haas

Papers

Thermally reversible homopolymer gel systems

Microscopic capsules and process for their preparation

Synthetic thermally reversible gel systems. II

Experimental study of copolymerization. II

Hydroxyethyl nylon, a new flexible superpolyamide derivative