Haloaldehyde polymers: 11. Polybromal

Bromal has been purified by stirring it with SbF₃ at elevated temperatures. This treatment removed small amounts of impurities which had prevented the polymerization of bromal previously. Monomer grade bromal polymerized readily with selected anionic and cationic initiators at low temperatures. While the chemical structure of the polymer as a polyacetal was similar to that of other perhaloaldehyde polymers, the interplanar spacings of polybromal as determined by wide-angle X-ray studies indicated a significant deviation of the crystal structure from that of other perhaloacetaldehyde polymers, for example, polychloral or even polydibromochloroacetaldehyde. Polybromal degraded thermally to give a quantitative yield of monomer and had a 1 M ceiling temperature of ?75°C. Copolymerization attempts of bromal with chloral under anionic conditions gave polymers incorporating only trace amounts of bromal, but bromal copolymers with phenyl isocyanate of various compositions, even of a 1:1 composition, could be readily prepared.     

Head to head polymers

Pure head to head (H–H) addition polymers, such as H–H polyolefins, H–H acrylates and H–H poly(vinyl halides), have been of interest for the understanding of the structure/properties relationship of addition polymers. These polymer structures have provided challenges of synthesis, characterization and of the measurements of their mechanical and rheological properties. H–H polymers have never been prepared by direct synthesis and indirect polymerization techniques have to be used. Some of the H–H polymers, the polyolefins, were made by polymerization of properly substituted dienes followed by hydrogenation. The H–H polyacrylates were synthesized by copolymerization followed by polymer reactions and the poly(vinyl halides), by halogenation of poly(1,4-butadiene). Improved halogenation techniques for poly(1,4-butadiene) have made H–H poly(vinyl chloride) and H–H poly(vinyl bromide) accessible in larger quantities and have allowed an extensive characterization of these polymers.

Blends of H–H with H–T polymers as well as H–H polymers with other polymers were studied. H–H Poly(vinyl chloride) or poly(vinyl bromide) blends with polycaprolactone and poly(methyl methacrylate) were also investigated. The thermal behavior and the thermal degradation behavior of these blends were investigated. The most striking result of these investigations was that H–H and H–T poly(vinyl chloride) are immiscible as is H–H and H–T polyisobutylene over almost the entire range of compositions.     

Adhesion of glow discharge polymers to metals and polymers

Adhesion of glow discharge polymers to metals and polymers in an adhesive joint was measured by lap-shear test and immersion in hot water of 70°C °C for an extended time. A glow discharge polymer was deposited onto polymers [polyethylene and poly(tetrafluoroethylene)] and metals (aluminum and stainless steel) prior to when the polymer and metal were joined. It is found that the lap-shear strength is enhanced by coating the surfaces of these substrates with plasma film produced from methane, ethylene, and acetylene, and that deterioration of the adhesive bonding part, when immersed in hot water of 70°C, is strongly dependent on the gas used as well as operational conditions where a polymer film is formed. The adhesion of a polymer produced from methane on the polymer and metal is strong enough to apply for durable, adhesive joints.     

Nanotubes as polymers

In this review, we show that the structure and behavior of single-walled nanotubes (SWNTs) are essentially polymeric; in fact, many have referred to SWNTs as “the ultimate polymer”. The classification of SWNTS as polymers is explored by comparing the structure, properties, phase behavior, rheology, processing, and applications of SWNTs with those of rigid-rod polymers. Special attention is given to research efforts focusing on the use of SWNTs as molecular composites (also termed nanocomposites) with SWNTs as the filler and flexible polymer chains as the host. This perspective of “SWNTs as polymers” allows the methods, applications, and theoretical framework of polymer science to be appropriated and applied to nanotubes.     

Some surface properties of plasma polymers prepared from hexamethyldisilazane and diethylaminotrimethylsilane

Plasma polymers from some silyl amines were produced by the radio frequency of 13.56 MHz, and the surface properties were investigated. The polymers were revealed to be as hydrophobic as a plasma polymer from tetramethylsilane, which does not contain nitrogen. The hydrophobicity became effective at around 50 Å thicknesses of these polymer layers deposited on micro-slide glass. These polymers have gradually become comparatively hydrophilic with the aging. The change of wettability is probably due to the oxidation of these surface layers to form oxides and peroxides, which are more hydrophilic. The hydrophobic character of silyl amine plasma polymers could be explained by the lack of amines and/or amides in these polymers, as observed with ATR-IR and ESCA spectra. These spectroscopic observations also suggest that nitrogen is a more fragile element in plasma than carbon or silicon in the silyl amines.     

Rheology of core cross-linked star polymers

The rheological characterization for a set of structurally diverse core cross-linked star (CCS) polymers is presented. The influence of arm molecular weight (M_w(arm)) and CCS polymer molecular weight (M_w(CCSP)) on the steady- and dynamic-shear properties determined by plate rheometry will be discussed. Both these parameters dramatically affect the CCS polymer solution properties and determine its “molecular softness”; a key feature of star polymers. Data from light scattering and capillary viscometry analysis are also presented to relate the dimensional configuration of the CCS polymers to their rheological properties. The methodology for tuning the structure of the CCS polymer is provided and the implications on solution properties are discussed.     

Proton-conducting polymer electrolyte membranes based on hydrocarbon polymers

This paper presents an overview of the synthesis, chemical and electrochemical properties, and polymer electrolyte fuel cell applications of new proton-conducting polymer electrolyte membranes based on hydrocarbon polymers. Due to their chemical stability, high degree of proton conductivity, and remarkable mechanical properties, perfluorinated polymer electrolytes such as Nafion^®, Aciplex^®, Flemion^®, and Dow membranes are some of the most promising electrolyte membranes for polymer electrolyte fuel cells. A number of reviews on the synthesis, electrochemical properties, and fuel cell applications of perfluorinated polymer electrolytes have also appeared during this period. While perfluorinated polymer electrolytes have satisfactory properties for a successful fuel cell electrolyte membrane, the major drawbacks to large-scale commercial use involve cost and low proton-conductivities at high temperatures and low humidities. Presently, one of the most promising ways to obtain high performance proton-conducting polymer electrolyte membranes is the use of hydrocarbon polymers for the polymer backbone. The present review attempts for the first time to summarize the synthesis, chemical and electrochemical properties, and fuel cell applications of new proton-conducting polymer electrolytes based on hydrocarbon polymers that have been made during the past decade.     

The significance of the rubber damping peak in rubber-modified polymers

Dynamic mechanical properties have been used as the basis for some important conclusions with regards to the physical properties of rubber-modified high-impact polymers. This paper attempts to show that conclusions of this type should be limited to fairly narrow groupings of polymers. Since the size, shape, and position on the temperature scale of a damping peak are influenced by composition, morphology, and method of polymer preparation, the significance of the damping peak associated with the rubber phase of the polymer has probably been generalized to too great an extent. Two examples of polymer groupings are given to illustrate the need for caution in attaching significance to the dynamic mechanical properties of polymers. Also given are two fairly narrow polymer groupings to show to what extent dynamic mechanical properties can be used for a correlation with impact strength and rubber concentration.     

The colloidal properties of alkaline‐soluble waterborne polymers

Waterborne polymer dispersions are widely used in coatings and graphic arts markets as environmentally friendly and more sustainable alternatives to solvent borne binders. Traditionally, waterborne (meth)acrylic dispersions are prepared by emulsion polymerization using low molar mass surfactants as a key ingredient to control particle size. However, these surfactants can have a negative influence on the performance of coatings such as reduced water resistance and adhesion. To mitigate the negative effects of surfactants, polymer latexes have been developed that employ alkaline‐soluble polymers as the sole stabilizer for a subsequent emulsion polymerization step. In this way surfactant‐free polymer dispersions are obtained. Despite the high commercial impact and relevance of this technology, fundamental studies regarding the physicochemical properties of the alkaline‐soluble polymers are lacking. In this article, the synthesis and colloidal properties of alkaline‐soluble waterborne methacrylic copolymers are reported. The dissolution behavior and colloidal properties of these alkaline‐soluble polymers were studied as function of molar mass, acid content, and pH. The dissolving polymer particles were characterized using static and dynamic light scattering, static and dynamic surface tension measurements, and cryogenic‐transmission electron microscopy analysis. It is concluded that the dissolution mechanism of alkaline‐soluble polymers follows a gradual process. As the pH increases deprotonation of the carboxylic acid groups swells the particle enhancing the further swelling with water. At a certain amount of base, the particles disintegrate into small polymer aggregates while the most water‐soluble polymer chains are dissolved in the water phase. An important learning is that part of the alkaline‐soluble polymer resides in very small particles (<5 nm). The formation of these polymer particles below 5 nm was not reported previously and offers a new insight into the dissolution mechanism of alkaline soluble polymers. The most important parameter steering this process is the acid value of the polymer, while the molar mass plays a modest role. The understanding gained in this study can be used to further advance alkaline‐soluble polymers as stabilizer in surfactant‐free emulsion polymerization technology, improving the performance of a wide range of industrially relevant coatings. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46168.     

Electrical properties of composites based on conjugated polymers and conductive fillers

Composite materials based on undoped conjugated polymers and conductive filler were synthesized and their electrophysical and electrochemical properties were investigated. Conjugated polymers such as polyaniline (PANI), polyacetylene (PA) and typical polymer dielectric, polypropylene (PP) were used as matrices. Graphite and single-walled nanotubes were used as conductive fillers. The investigation of the dependencies of conductivity on filler concentration show that in contrast to PP and PANI, PA becomes conductive due to injected charge carriers from filler particles. This conclusion is supported by investigated dependencies of composite conductivity on temperature and time during aging and on cyclic voltammetry data. It was shown that a conjugated polymer matrix allows composite materials with new electrophysical and electrochemical properties to be produced.     

Effect of water absorption on physical properties of high nitrile barrier polymers

Water absorption studies were made on a series of high nitrile barrier polymers, as a function of polymer composition, rubber content, temperature, orientation and relative humidity. Results indicate that absorbed water has a great influence on both mechanical and thermal properties of the polymer. Absorbed water in high nitrile polymers causes a large decrease in the glass transition temperature and yield stress. These effects are found to depend on polymer composition, amount of absorbed water, and degree of orientation. The significance of these results is discussed in relation to end-use properties of the polymer.     

星形聚合物的发展近况

综述了采用负离子聚合技术合成的星形聚合物的结构与性能的关系、合成路线及应用。新开发的星形聚合物,如ＳＳＢＲ,ＬＣＢＲ,ＭＶＢＲ,ＨＶＢＲ,ＳＩＢＲ等,运用高分子分子设计的方法来合成,因而具有更佳的综合性能,如高的抗湿滑性及低的滚动阻力等。     

Modifying and managing the surface properties of polymers

An ongoing challenge in polymer science is the preparation of materials with bespoke surface properties which differ from that of the bulk, for example hydrophobicity, wettability, chemical resistance, adhesion or biocompatibility. We highlight here recent efforts in the design, development and application of (multi)end‐functionalized polymers as additives for the efficient modification of polymer surface properties. Aryl‐ether moieties bearing up to eight functional groups have been used as initiators for the controlled polymerization of both styrene and methyl methacrylate by atom transfer radical polymerization (ATRP) and of lactide by ring opening polymerization (ROP). The resulting polymers have been used as additives to modify the surfaces of the corresponding bulk polymers. Fluorinated polymer surfaces are particularly appealing in terms of their liquid repellence, chemical inertness and low coefficient of friction. When an additive consisting of a low molecular weight polystyrene chain, end‐capped with four C₈F₁₇ groups, is present in a matrix of polystyrene at levels as low as 0.1%, near polytetrafluoroethylene‐like surface properties result. Copyright © 2007 Society of Chemical Industry     

Redox polymers based on polyamines

Conditions of formation of redox polymers based on quinones were studied. The ways of synthesis of macromolecules containing primary amino group via nitration and reduction of polymers, chemical modification and polymerization are discussed. Some pecularities of reduction of nitrated high molecular compounds in comparison with low molecular weight analogs were established. The effect of the polymer matrix on the reactivity of the amino group in nucleophilic substitution has been studied. The ways of increasing the activity of the primary amino group in the initial polyamines by changing the substituent are discussed, as well as the effect of the type of quinoid compound on the yield and properties of polymers formed. Polyaminoquinones were used for the preparation of ion-selective film electrodes without an inner liquid compartment. The redox polymer provided thermodynamic reversibility on the membrane-electron conductor interface. As a result a stable functioning ion-selective electrode with an inner contact has been prepared.     

Structure and properties of microcomposites and macrocomposites from block polymers

The incorporation of a rubber phase in glassy polymers, as is well known in the case of high impact polystyrene, leads-to an increase in their impact strength. Block polymers offer three principal approaches for obtaining multiphase glassy polymers in which an elastorner phase is present in the matrix of the glassy polymer. They are: (1) control ofblock polymer composition, (2) blending of block polymer with homopolymers, and (3) polymerization of a solution.of a block polymer in the monomer corresponding to one of the blocks. The observed properties, such as impact strength, modulus, and heat distortion temperature, desired in rubber modified glassy polymers are discussed for block polymer systems prepared using the above approaches.     

Fullerene functionalized polymers

Summary The recent synthesis and macroscopic isolation of C₆₀ (buckminsterfullerene) has stimulated interest in its properties and chemical reactivity. Fullerenes are known to be attacked by nucleophiles and it has been reported that they react with small amines. There is, however, no report on the reaction of fullerenes with polymeric amines. Fullerenes were found to add to amine containing flexible hydrocarbon polymers such as ethylene propylene terpolymer (EPDM-amine) to obtain novel C₆₀ functionalized polymers. These materials are soluble in common solvents. The reaction of the fullerene and polymer was followed by infra-red spectroscopy and viscosity measurements.     

Macrocyclic polymers and related products derived from aromatic nitriles

A method of obtaining macrocyclic compounds by stepwise condensation of aromatic and heterocyclic nitriles with amines is described. The technique was extended to give polymers containing repeating macrocyclic units, and to show the optimum reaction conditions. The properties of these polymers and possible applications are discussed. Related polymer systems such as the polybenzobis(aminoiminopyrrolenines), the polybenzimidazoles and the polybenziminobenzimidazoles were also obtained by an adaptation of the method.     

Dielectric rheological measurements of molten polymers

Rheological characterization of polymers above their melting points is performed with dielectric spectroscopy. A new in‐line interdigitated dielectric sensor as well as a commercial off‐line sensor were used to make the measurements. The dielectric dissipation or loss factor of a molten polymer was found to be directly proportional to independently measured rheological properties of the polymer. Time‐temperature superposition was used to translate dielectric and rheological curves to master curves where the curves are comparable in form, but the activation energy of a dielectrically‐induced relaxation was found to be lower than a rheological translational motion. The more localized and homogeneous effects imparted to the polymer during the dielectric measurement may cause the polymer to undergo a viscoelastic transition at a lower energy than the flow‐induced transition in rheological measurements. The dielectric methods detailed herein provide a new noninvasive technique to measure the viscoelastic properties of molten polymers.     

The study of PET recyclable polymers as paper coatings

Two PET recyclable polymers, EvCote^® PGLR-30 and EvCote^® PWRH-30, at four ratios (0, 5, 10, 15 wt%) were studied as components of paper basecoats. The results showed that 5% of the PET recyclable polymer was the optimum ratio with regard to properties of the coated paper, particularly MVTR (moisture vapor transmission rate) and Cobb. Both of the PET recyclable polymers were evaluated as a paper topcoat as well. The results showed that both of the PET polymers as topcoats could provide excellent MVTR and Cobb properties, particularly combining with the optimized PET polymer used in the basecoat. It was also found that when the PET polymer was used as the topcoat, the effect of clay/latex ratio in the basecoat was important: more clay gave better MVTR and repulpability.     

Viscoelastic properties of fibre from a mixture of aromatic polymers

Conclusions The temperature dependence of the dynamic properties of fibres from a mixture of crystalline polymers is not a superposition of the corresponding dependences for fibres from the individual polymers.The relaxation properties of fibres from a mixture are determined by the properties of the polymer which forms the matrix.The increase in temperature of the basic relaxation transition and the decrease in its intensity which are observed for the polymer matrix as compared with the starting polymer are caused by a change in its structure, whose formation is affected by the content of the second component in preparing fibres from the mixture, and also by the possibility of a reinforcing action of the disperse phase.Translated from Khimicheskie Volokna, No. 2, pp. 29–30, March–April, 1984.