Effect of Laser Radiation on Dyed Polymeric Films

Abstract

Destruction of the thin dyed polymeric films under the action of resonant and non-resonant laser radiation has been investigated. It is shown thai laser stability of dyed polymers depends on the type of incorporated dye and it is independent of film thickness and dye concentration at the same powers of absorbed laser radiation. Moreover, laser stability of polymeric films with chemically bonded dye is higher than the polymer stability with dissolved dye. Comparative analysis showed that the polymer laser stability is determined by the kinetics of the polymer thermodegradation. which results in the appearance and accumulation of the products absorbing laser radiation. It is established that resonant irradiation of dyed polymers is considerably more efficient for polymer destruction than the nonresonant one.     

Changes of Mechanical Strength and Chemical Structure of Polymers Containing Aromatic Groups in the Plasma of Electrical Discharges

Abstract

The effect of electric discharge plasma on various aromatic polymers has been studied. When the oxygen plasma causes the destruction processes and oxidation only in thin surface layers the hydrogen plasma causes the changes of polymer structure in much deeper ones (up to 100–200 mcm).

The long-term stability of polymers in electric discharge plasma is compared with that in “Xenotest.”     

On the Mechanism of Laser Destruction of Polymers: Effect of Low-molecular Weight Additives Stemming from Oscillatory Cross Relaxation

Abstract

The vibrational cross-relaxation mechanism of polymer destruction suppression under laser irradiation are discussed. The experimental data are presented showing the influence of low molecular weight additives on laser damage resistance of optical polymers.     

The Entropic Mechanism of Water Solvation of Polymers

Abstract

Computational analysis of isotherms of equilibrium water absorption by polymers indicates the isotherms follow the theory of volume-centered filling of micropores regardless of the hydrophilicity of polymers. Structure of a microporous adsorbent, absent in the initial state, is formed through reorganization of chains of the molecular-chain sponge during adsorption. Thus, a part of chain units is combined in micropores isolating water molecules as clusters, and another part is redistributed around the clusters as a fringe that stabilizes the system by increasing the configuration entropy.

The problem of the physical state of sorbed water in polymers is important from positions of the mechanisms of its diffusion in polymeric membranes, its effect on physical properties of polymers, participation in dyeing and fading of fabrics, superseding of stabilizers and plasticizers, and also in guided delivering of drugs in the organism from polymeric units of medical use.     

Rolltrusion Processing of Polymers for Property Enhancement

Abstract

Rolltrusion is a single step solid state deformation process that has been successfully applied to many polymers and copolymers to produce unique properties. Property enhancement results in 3D mechanically improved behavior over the original workpiece without the need for cross-plying. Processing-structure-property relationships have been established. Rolltruded polymers are transparent since they are free of spherulites, rather they are comprised of anisotropic small crystallites formed from spherulites. The crystallites are crystallographically arrayed and interconnected by tie molecules that provide property improvement in three mutually perpendicular directions. Thin films have also been made and these may be used as membranes for the separation of small molecules. Permselective membranes so formed are pinhole free and very strong with a regulated 3D morphology. The rolltrusion technique is not restricted by the solubility constraints inherent in preparing solvent based thin films. Consequently, engineering plastics may be made into membranes without regard for their limited solvent solubility. Rolltrusion has now been established as a universal procedure for property enhancement of commercial and engineering polymers.     

Photosensitive Polymers

Abstract

The present summary covers photophysical and photochemical processes in polymers and their applications; photopolymerization is not included. The main research interests in the field of photosensitive polymers has now shifted from fundamental studies on photophysical and photochemical processes to the area of applications such as photoresponsive polymers, image forming and optical memory materials.     

Self-Assembly of Polymers through Dynamic Coordination Chemistry and Hydrogen Bonding: Polymers from Mercury(II) Halides and Bis(amidopyridine) Ligands

The synthesis of hybrid organic–inorganic polymers by combination of mercury(II) halides with the ligand 1,5-bis(isonicotinamido)naphthalene, C₁₀H₆(NHCO-4-C₅H₄N)₂, 1. The compounds of formula [HgX₂(1)] form either linear (X = Cl, Br) or zig-zag (X = I) polymers and contain tetrahedral mercury(II) centers with bridging ligands 1. The polymers are further assembled by hydrogen bonding between amide groups. When X = Cl or Br, two-dimensional sheet structures are formed whereas, when X = I, a three-dimensional network is formed. A new polymeric form of [HgCl₂(Me₂SO)] is also described. Dedicated to Ian Manners for his pioneering research on organometallic polymers     

Chemical Modification of Fiber-forming Polymers Based on Recombination Addition Reactions

Abstract

The essence of chemical modification processes of fiber-forming polymers based on recombination addition reactions involves preliminary sorption of low-molecular components by the fiber being in a high elasticity state with the subsequent transfer of interacting substances into a free radical state as a result of chemical or radiation initiation. Recombination of activated parts then leads to the fixation of a low-molecular component in a polymer matrix.

Various versions of these reactions based on modifications of fibrillar proteins (fibroin and keratin). polyamides. cellulose and its esters, polyvinyl alcohol with ionogenic (cationic and anionic) and non-ionogenic (disperse) dyes of different classes have been considered.     

Polymers in High Performance Structures

Abstract

The continuing need for “high performance” in the application of polymers will provide a driving force for modification of polymers to achieve these characteristics. Some specific considerations with respect to polymers, properties and uses are presented as possible guides to future developments.     

Fluorescence polarization changes in electrically oriented solutions of dye-tagged polymers

Dilute aqueous solutions of poly(methacrylic acid) (M = 7.8 × 10⁵) and sodium polystyrene sulphonate (M = 1.3 × 10⁵) when tagged with the dye acridine orange, have been subjected to pulsed electric fields. Changes have been recorded for the polarized components of the fluorescence with each polymer system, during the application of the electric fields. From these fluorescent changes, which were recorded for wavelengths above 515 nm when radiation of 488 nm was incident, the nature of binding of the dye to these polymers has been estimated. For each system, the planar dye molecules appear to bind parallel to the polymer backbone.     

Polymers as Materials

Abstract

The chemistry and technology of polymers has developed rapidly during the last three decades; it concerns itself with materials consisting essentially of the elements C, H, N, and O, and being therefore conventionally classified as organic polymers. However, in many instances other elements such as B, Si, P, S, F, and CI are present in certain proportions and have a more or less important influence on the ultimate properties of the products. Together with the large family of metallic compounds and ceramic systems, organic polymers represent useful and increasingly important engineering materials in the construction of buildings, vehicles, engines, applicanes, textiles, packaging, printing and writing materials, plastics, rubber goods and household articles of all kinds.     

Synthesis and Characterization of One-Dimensional Zinc(II) Coordination Polymers as Precursors for Preparation of ZnO Nanoparticles via Thermal Decomposition

Two new Zn(II) coordination polymers from the ligand, 2,5-bis(3-pyridyl)-3,4-diaza-2,4-hexadiene (bpdh), with different anions; i.e., [Zn(μ-bpdh)(H₂O)₄](ClO₄)₂·2bpdh (1) and [Zn(μ-bpdh)(H₂O)₄](NO₃)₂·2bpdh (2), were synthesized and characterized by IR spectroscopy, elemental analyses and X-ray crystallography. Compounds 1 and 2 are 1D coordination polymers and the zinc atoms are linked by four oxygen atoms from water molecules and two nitrogen atoms of bpdh ligands. There are two uncoordinated bpdh ligands that, along with the perchlorate or nitrate anions, form hydrogen bonds with water molecules. ZnO nanoparticles were obtained by thermolysis of 1–2 in oleic acid at 280 °C in air. The ZnO nanoparticles were characterized by X-ray diffraction and scanning electron microscopy.     

Synthesis of Metal-containing Polymers via Ring Opening Metathesis Polymerization (ROMP). Part II: Polymers Containing Transition Metals

Following from Part I (this journal, 18(1), 2008), dedicated to main group metal containing polymers obtained by ROMP, the application of the same progressive concept to prepare polymers having this time transition metals in the side- or main-chain is here critically overviewed. These TMC polymers were produced through ROMP reactions promoted by Schrock’s Mo-carbene or the Grubbs’ Ru-carbene catalysts, the most recent and unique methodology for obtaining wished for structures. While discussing main aspects of these target-driven syntheses, as well as properties and applications of the neutral and cationic transition metal containing polymers, emphasis is laid upon organoiron macromolecules based on ferrocene scaffolds. Special attention is given to electrochemical behavior and thermal characteristics. Topics also cover polymers with other transition metals such as Co, Ni, Ru, Pd and Pt, which are important for generating zero valent metal nanoclusters in polymer films. Finally highlighted are some illustrative examples of metal-linked, metallodendrimers and hyperbranched, dendritic and star polymers.

Synthesis and Reactions of Organometallic Polymers Containing Titanacyclobutene Units in the Main Chain

A new class of polymers containing titanacyclobutene units in the main chain were prepared by the reaction of organic dihalides (2) with a binuclear titanium propargyl complex (3) generated in situ from bis(pentamethylcyclopentadienyl)titanium chloride (Cp*₂TiCl, 1), SmI₂, and 1,4-bis(3-bromopropynyl)benzene (2a). The dark red colored polymers (4) thus obtained are soluble in organic solvents such as tetrahydrofuran and chloroform, and they are stable at ambient temperature under argon atmosphere. The reaction of the titanium-containing polymers (4) with hydrogen chloride was found to give organic polymers (7) containing unsaturated main chain.     

Conformational Properties of Optically Active Stereoregular Polymers

Abstract

The relationship between configuration and conformation of Stereoregular polymers is reviewed. The reason for the frequent occurrence of helical conformations in the solid state is discussed, as well as the difficulties encountered in the experimental investigation of the conformational equilibrium of macromolecules in solution. As far as the local conformation of the repeat units of polymers in solution is concerned, satisfactory information is available only in the case of isotactic poly(α-olefins). This is mostly due to the successful combination of statistical mechanical calculations and experimental measurements of optical activity in isotactic poly(α-olefins) containing asymmetric carbon atoms in the lateral chain. In this case optical activity measurements provide a demonstration of the existence of the short range helical order in solution. It is further shown that a series of independent experiments (including some recent end-to-end distance measurements) confirm the detailed picture of the macromolecule in solution which was obtained through conformational analysis and statistical calculations. The influence of the asymmetry of the repeat unit on the main chain conformation is discussed, with reference to the analogous situation in biopolymers. The problem of conformational transitions is also considered and the difference in behaviour between Stereoregular synthetic polymers and biopolymers is discussed. Conformational transitions are related to the existence of conformational rigidity in macromolecules, and the thermodynamic and kinetic bases of this latter phenomenon are discussed. Further analogies and differences between the conformational properties of Stereoregular synthetic polymers and biopolymers are considered. Finally, it is shown how the data obtained for isotactic poly(α-olefins) can be generalized for understanding some of the basic features which characterize the conformation of macromolecules in solution.     

On the Theory of NMR Line Shapes in Amorphous Regions of Uniaxially Oriented Polymers

Abstract

A theory of NMR of protons belonging to highly-stretched polymer chains with fixed ends, e.g. tie molecules of amorphous regions of oriented semicrystalline polymers, is presented. Analysis is carried out in terms of the model of freely-jointed chains. All contributions to the line shape from the intramolecular dipole-dipole interactions (DDI) are taken into account. Expressions are derived for the residual time independent component of DDI and the second moments of the fluctuating DDI. The NMR spectra are described in terms of the Anderson-Weiss approximation. A number of spectra are calculated for polyethylene. It is shown that the linewidth of high lemperature spectrum rapidly grows with stretching and approaches that of crystallite polymer. It is demonstrated that the distribution function of tie molecules can, in principle, be obtained from the dependence of the spectra on the stretching ratio.     

Electric Strength of Polymers Under Vacuum at Cryogenic Temperatures

Abstract

The electric strength of solid polymers under high vacuum is investigated at a temperature ranging from 293°K down to that of liquid helium (5°K) under power frequency alternating- and direct-voltages. The electric strength of polymers was found to be very dependent on the pre-breakdown partial discharges when measured in cryogenic medium whether gas or liquid. When helium was used as coolant, discharges may extend very far from the electrodes and thus exerted high electric stresses on large areas of the sample under test. These discharges may produce flash-over and serious troubles. It may also lead to localised breakdown of polymers which may give apparent reduction in dielectric strength.

A large increase in the electric strength of polymers was observed when used at cryogenic temperatures under vacuum; the increase was very significant for polyethylene and polyimide specially under direct voltages.

The results showed promising properties and it is concluded that the high vacuum will offer the solution to many insulation problems at liquid helium temperatures in cryogenic and superconducting equipment.     

Synthesis of Conjugated Polymers Containing Phosphole with the 5-Member Fused Carbocycle

Summary Novel conjugated polymers 9a–c possessing the phosphole ring with the 5-member fused carbocycle were synthesized by palladium catalyzed coupling reaction of 1-phenyl-2,5-bis(p-bromophenyl)phosphole 7 with diethynylarenes 8a–c. The obtained polymers 9a–c had the regio-regulated 2,5-substituted phosphole ring in the polymer main chain, and were characterized by ¹H, ¹³C, ³¹P NMR, and FTIR. The ³¹P NMR spectra revealed that the extension of π-conjugation changed the phosphole ring angles. The optical properties of polymers 9a–c were independent of the size of the fused carbocycle.     

Synthesis, Structure, and Properties of Aromatic Ring-Layered Polymers Containing Ferrocene as a Terminal Unit

[2.2]Paracyclophane-layered polymers 4a and 4b end-capped by ferrocene and [2.2]paracyclophane, respectively, were synthesized by using a xanthene skeleton as a scaffold. Two model compounds, 4,5-bis(ferrocenylethynyl)-9,9-dimethylxanthene 7 and pseudo-p-bis(4-ferrocenylethynyl-9,9-dimethylxanthen-5-yl)[2.2]paracyclophane 8, comprising ferrocenes arranged in a face-to-face manner were also prepared. According to the X-ray molecular structure of compound 8, [2.2]paracyclophane between the ferrocenes had sufficient space for twisting and there was no interaction between two ferrocenes via [2.2]paracyclophane in the ground state. These polymers exhibited blue-light emission originating from the layered cyclophanes; however, the photoluminescence intensity of polymer 4a was lower than that of polymer 4b. The fluorescence emission of polymer 4a was effectively quenched by the end-capping ferrocene group. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Poly(urea-urethane) polymers with multi-functional properties

Polyurea-urethanes with multifunctional properties were synthesized by reacting 4,4′-diphenylmethane disocyanate (MDI) with a two diol mixture of polytetramethylene glycol (PTMG (1000, 2000) and biocidal quaternary ammonium monomer ((N-benzyl-N-dodecyl-N-bis2-hydroxyethyl) ammonium chloride (BDAC)), and extended with N-(2-hydroxyethyl) ethylene diamine (HEDA) to form PU polymers. The PU polymer was then grafted with a disperse dye via a coupling agent of epichlorohydrin to form a dye grafted polyurethane with biocidal and covalent bond dyeing properties. In consideration of the mechanical properties, it is found that both the modulus and the strength of the dye grafted PU polymer films are lower than those of pure PU polymers due to the bulkiness of their dye molecules. For thermal properties, the dye grafted PU polymers exhibit higher T_gh than those without dye molecules. However,neither the T_gs nor the T_ms vary in the presence of BDAC or dye molecules, but they are changed with various chain lengths of the soft segment. For dyeing properties, the effective dyeing efficiency of dye grafted PU is over 85%. Moreover, the dye grafted PU polymers exhibit lower dye migration (M_p%) than those of simple mixtures of PU and dyestuff, and they show a higher grade of color fastness when exposed to light. In the shake method of antibacterial testing, the modified PU polymers exhibit a long lasting biocidal activity.