IR laser-induced decomposition of poly(vinyl chloride-co-vinyl acetate): Control of products by irradiation conditions

IR laser-induced, ablative decomposition of poly(vinyl chloride-co-vinyl acetate) was examined under different irradiation conditions and its volatile and solid products were characterized by mass spectroscopy, infrared spectroscopy, Raman spectroscopy and UV spectroscopy and EDX-measurements. The laser decomposition of the copolymer, compared with that of poly(vinyl acetate) and poly(vinyl chloride), is revealed to be a more efficient process leading to solid films with the proportion of Cl- and CH₃C(O)O-groups controlled by irradiation conditions.     

IR laser ablative decomposition of poly(vinyl acetate) loaded with Fe and Cu particles

Pulsed IR laser-induced decomposition of poly(vinyl acetate) (PVAC) loaded with nanometer-sized Cu and micrometer-sized Fe particles results in the formation of gaseous products and deposition of polar crosslinked polymer films which contain metal (Cu and Fe) particles. The main volatile products are hydrocarbons, carbon oxides (CO and CO₂), molecular hydrogen and acetic acid. The deposited polymer films were characterized by FTIR, UV and XP spectra and by electron microscopy and thermogravimetry. They contain reactive conjugated CC bonds and ca. 50% of the initially present acetate groups. Residual reactivity of the CC bonds results in polymer crosslinking and decrease in solubility. The deposited, crosslinked PVAC-based films containing metal particles are less thermally stable than similar films not containing these particles. The reported process reveals feasible ablation of metal particles when embedded in a polymer and makes it possible to fabricate films of metal/polymer composites in which metal particles are completely protected by the polymer.     

IR laser ablative and conventional decomposition of poly(vinyl phenyl ketone): Different processes and different products

Pulsed IR laser ablation of poly(vinyl phenyl ketone) results in the formation of CO, C₁-C₄ hydrocarbons, benzene, styrene and phenylacetylene and affords deposition of polymeric films that were examined by EDX-SEM, FTIR, UV and NMR spectroscopies and gel-permeation chromatography. It is revealed that the structure of the films is affected by laser fluence and their M_w distribution is almost identical to that of poly(vinyl phenyl ketone). The formation of the products is accounted for by cleavages of both polymer backbone and pendant group. Conventional heating of poly(vinyl phenyl ketone) yields CO, formaldehyde, methanol and benzene as major volatile products and affords a solid fraction showing substantial fragmentation of the polymer. The different degradation products from both processes are ascribed to different modes of heating and to the wall effect.     

Sorbent coatings for solid-phase microextraction based on mixtures of polymeric ionic liquids

Four polymeric ionic liquids based on two different cations, poly(1‐vinyl‐3‐hexylimidazolium) and poly(1‐vinyl‐3‐hexadecylimidazolium), combined with two different anions, bis[(trifluoromethyl)sulfonyl]imide (NTf) and chloride (Cl^?), were combined in various weight percentages and used as sorbent coatings for solid‐phase microextraction gas chromatography (SPME‐GC). The selectivity of the fiber coatings for 12 test analytes was examined. The extraction efficiency of n‐alcohols increased with an increase in the weight percentage of chloride ion in the sorbent coating. The ability to tune the interactions between the coating material and the analytes was exploited and resulted in distinct changes in the limits of detection for hydrogen‐bonding analytes with varying chloride ion content in the sorbent coating.     

IR laser ablative degradation of poly(phenylene ether-sulfone): Deposition of films containing ether, sulfone, sulfoxide and sulfide groups

Pulsed infrared laser-induced ablation of poly(1,4-phenylene ether-sulfone) (PES) results in the extrusion of SO₂, CO and hydrocarbon molecules and allows deposition of dark solid paramagnetic carbonaceous films that were analysed by FTIR, UV, XP, Raman and EPR spectroscopy and by electron microscopy and revealed as poor in S and containing CO, SO₂, -SO- and C-S-C units. The films show pronounced conjugation of sp²-C atoms and their EPR spectra are sensitive function of the presence of molecular oxygen. The laser process differs from the conventional pyrolysis of PES which yields SO₂ and phenol as major volatile products and a carbonaceous char.     

Heat capacities and entropies of liquid polyfluoroethylenes and polychloroethylenes

Through new measurements and from literature data, the heat capacity of all liquid polyfluoroethylenes could be established as: above 480 k, and as below 480 K in J/(K mol), where N_F is the mole fraction of F atoms. In connection with previously established heat capacities of the solid polymers, enthalpies, entropies, and residual entropies of the glassy state at 0 K were computed. Data for liquid polychloroethylenes are much less complete, and the thermodynamic functions could only be established for liquid poly(vinyl chloride) and compared with the data for solid poly(vinyl chloride), poly(vinylidene chloride), and polychlorotrifluoroethylene.     

IR laser ablative decomposition and depolymerisation/repolymerisation of poly(ethylene succinate)

Pulsed IR laser ablation of poly(ethylene succinate) results in the formation of volatile products (mainly carbon oxides, hydrogen, C₁-C₄ hydrocarbons) and affords deposition of polymeric films. Composition, structure and molecular weight distribution of the latter products were examined by EDX-SEM, FTIR, UV and NMR spectroscopy and gel permeation chromatography and revealed to be virtually identical to the initial poly(ethylene succinate). The deposited films and poly(ethylene succinate) decompose in the same way, as proved by TGA analysis. The formation of the volatile products is accounted for by random cleavages of the polymer backbone. The deposition of the polymeric products is judged to be due to molecular ester group interchange and/or a sequence of the C-C bond homolysis and recombination of the produced radicals.     

IR Laser‐Induced Degradation of Poly(vinyl acetate): Novel Thermal Reactions in Solid Polymers

Summary: Pulsed‐IR laser‐induced decomposition of poly(vinyl acetate) (PVAC) differs remarkably from its conventional pyrolysis, which results in the formation of acetic acid and non‐polar carbonaceous residue. In contrast, the products in the former case are (i) vinyl acetate (low energy channel), (ii) products of cleavage in the acetate group, and (iii) an ablatively deposited polar polymeric film containing roughly half of the acetoxy groups initially present.

Schematic of the different routes of poly(vinyl acetate) degradation.     

Thermodynamics of miscible polymer blends using a concentration-dependent χ parameter

The Flory equation-of-state theory, as expressed by Patterson and co-workers, has been applied to two miscible polymer blends: poly(vinyl chloride)/poly(ε-caprolactone) and poly(methyl methacrylate)/poly(vinylidene chloride). For both blends, the variation of the polymer-polymer interaction parameter, χ, as a function of composition, is mostly small and can be accounted for by the Flory theory. However, for poly(vinyl chloride)/poly(ε-caprolactone) blends, at high poly(ε-caprolactone content), the large variation of χ as a function of concentration can be explained by a variation of the surface-to-volume ratio of the polymers in the mixture with blend composition. The variations of the surface-to-volume ratios determined in this study agree with those reported in the literature using small-angle x-ray scattering.     

Semi-interpenetrating polymer networks of polyurethane and poly(vinyl chloride)

Summary A series of semi-interpenetrating polymer networks (semi-IPN) of polyurethane (PU) and poly(vinyl chloride) (PVC) has been obtained by prepolymer method and characterised by FTIR; morphological features were examined by SEM-EDS. It has been found that PVC spherical aggregates are dispersed in the PU matrix, but Cl atoms location indicates partial miscibility of both polymers at the interphase which is probably due to hydrogen bonding and/or dipole-dipole interactions. The PVC component influences the phase behaviour of PUs hard segments, as evidenced by DSC results. Thermogravimetric analysis (TG) reveals a complex, multi-step decomposition process with the main mass loss at 503-693 K, while the DTG maxima are located between 540 and 602 K.     

IR laser ablative degradation of poly(ethylene terephthalate): Formation of insoluble films with differently bonded CO groups

IR laser-induced degradation of poly(ethylene terephthalate) (PET) was studied under different irradiation conditions and the ablated volatile and solid products were characterized by mass and infrared spectroscopy, gel-permeation chromatography, thermogravimetry and electron microscopy. The observed volatile products (carbon oxides, H₂, C_1-2 hydrocarbons, acetaldehyde, benzene and toluene) and less-volatile aromatic compounds are typical products of thermal degradation of PET. The ablatively deposited solid materials are a blend of soluble, structurally similar oligomers and of an insoluble polymer containing carbonyl groups bonded in a -C(O)OH arrangement. Thermal degradation of these deposited solids is controlled by decomposition of sublimed fractions and is easier than that of PET.     

Photolithographic Patterning of a Conductive Polymer Using a Polymeric Photoacid Generator and a Traceless Removable Group

Summary: In the present communication we describe a photolithographic method to produce polyaniline (PANI) patterns using PANI modified with a traceless removable functional group (nitrosated polyaniline, PANI‐NO) and external inexpensive polymeric photoacid generators (poly(vinyl chloride), PVC). Therefore, residual sub‐products created by irradiation of the plate do not remain occluded in the polymeric films. The borders of the patterns are better defined than in the case of chemical lithography using inorganic acids as the hydrolyzing agent.

     

Poly(vinyl chloride) Nanocomposites

Poly(vinyl chloride) is one of the major thermoplastics beside other commodities polymers like polyethylene and polystyrene. However, some of its main characteristics such as plasticity, thermal and photo stability are inferior to other commodity polymers. Adding nano scale inorganic fillers to poly(vinyl chloride) or other polymers in view to obtain polymer nanocomposites with superior properties has drawn the attention of many researchers in the last decades. Poly(vinyl chloride) nanocomposites are obtained mainly by in situ polymerization, solution based or mixing techniques. The resulting products show improvement of most important properties of poly(vinyl chloride) such as thermal, mechanical, rheological, flammability, antibacterial, etc. This paper presents preparation ways of poly(vinyl chloride) nanocomposites using different nano fillers and the improved properties compared with those of virgin poly(vinyl chloride).     

Study on the Mechanism of the Radiation-Induced Chain Oxidation of N,N,N,N-Tetramethyl-4,4′-diaminodiphenylmethane by Tetrabromomethane in Poly(vinyl chloride) Films

Kinetics and mechanism of the radiation-induced chain oxidation of N,N,N,N-tetramethyl-4,4-diaminodiphenylmethane (Am) by tetrabromomethane in poly(vinyl chloride) (PVC) films were studied by ESR and optical spectroscopy. The quantitative analysis of the ESR spectra of PVC films containing Am and CBr₄ irradiated with -rays at 77 K was performed. The nature of radical species involved in the chain process was established. It was shown that the heating of the films after their irradiation at 77 K resulted in the formation of free radicals Am^·, which initiated the chain oxidation of amine with a chain length of 100. The kinetic features of the chain oxidation–reduction reactions occurring in vacuum and in the presence of oxygen were compared.     

THE COMPATIBILITY OF BLENDS OF POLY(VINYL CHLORIDE) OR CHLORINATED POLY(VINYL CHLORIDE) WITH POLY(METHYL METHACRYLATE)

IR spectral shifts of carbonyl vibrational absorption for ethyl acetate, which acts analogically as the structural unit of poly(methyl methacrylate), in cyclohexane, chloroform, chlorinated paraffins, poly(vinyl chloride) and chlorinated poly(vinyl chloride) were measured. The results suggest that there are specific interactions between the carbonyl groups and the chlorinated hydrocarbons which could be responsible for the apparent compatibility of poly(vinyl chloride)—poly(methyl methacrylate) and chlorinated poly(vinyl chloride)—poly(methyl methacrylate) blends. Additionally, the effects of the preparation mode of blend films on phase separation and observed compatibility are discussed.     

Layer-by-layer self-assembly preparation of layered double hydroxide/polyelectrolyte nanofilms monitored by surface plasmon resonance spectroscopy

Layer-by-layer self-assembly was used to prepare nanofilms of (2:1) MgAl-layered double hydroxide (LDH) nanoparticles and polyacrylic acid or sodium polystyrene sulfonate. The multilayers were attached to ~50-nm thick gold films on microscopy glass slides prepared by vacuum evaporation. The contact between the gold film and the multilayered films was mediated via surface modification with thiols, adsorption of poly(diallyl dimethyl ammonium) chloride (PDDA) or direct binding of the LDH particles. Surface plasmon resonance (SPR) spectra of the multilayered films were analyzed by fitting the Fresnel equations. The shifts in the SPR angle (_SPR) due to the adsorption/deposition on the gold surface were used to evaluate the process of building up the multilayers. Strong surface/multilayer contact formed when electrostatic attraction and hydrophobic interaction were combined as in the case of mercaptopropanoic acid or PDDA sticking layers. The LDH suspension concentration strongly influenced the number of deposited layers. The multilayer films were investigated by reflection FT-IR spectroscopy.     

Evaluation of Polyurethane-Based Membrane Matrices for Optical Ion-Selective Sensors

Abstract

Plasticized thin films of polyurethane (PU) mixed with poly(vinyl chloride)(PVC) or a terpolymer of poly(vinyl chloride)/(vinyl acetate)/(vinyl alcohol) (PVA) are examined as membrane matrices for the preparation of reversible optical ion sensors. Optical sensors for Na⁺, NH₄ ⁺, Cl^? and ClO₄ ^? are prepared by casting thin films of the polymer mixtures (PU/PVC (1:1 wt) and PU/PVA (4:1 wt)) containing appropriate ion carriers and pH chromophores on glass slides. The optical response properties of these membranes is essentially the same as conventional pure PVC membranes reported in the literature. However, significantly enhanced membrane adhesion to glass or silicon wafer surfaces is observed using the polyurethane based matrices, making them more suitable than PVC for use in the development of solid-state optical ion sensing devices.     

Tin-Naphthalene Sulfonic Acid Complexes as Photostabilizers for Poly(vinyl chloride)

Poly(vinyl chloride) degrades when exposed to ultraviolet light for long durations; therefore, the photostability of polymeric materials should be enhanced through the application of additives. New organotin complexes containing 4-aminonaphthalene-1-sulfonic acid were synthesized and their role as poly(vinyl chloride) photostabilizers were evaluated. The reaction of 4-amino-3-hydroxynaphthalene-1-sulfonic acid and appropriate di- or trisubstituted tin chloride (triphenyltin chloride, tributyltin chloride, dibutyltin dichloride, and dimethyltin dichloride) in methanol under reflux gave the corresponding tin-naphthalene complexes with yields of 75%–95%. Elemental analyses and spectroscopic techniques including infrared and nuclear magnetic resonance (proton and tin) were used to confirm their structures. The tin complexes were added to poly(vinyl chloride) to produce thin films that irradiated with ultraviolet light. Various parameters were assessed, such as the weight loss, formation of specific functional groups, changes in the surface due to photoirradiation, and rate constant of photodegradation, to test the role played by the organotin complexes to reduce photodegradation in polymeric films. The results proved that organotin complexes acted as photostabilizers in these circumstances. The weight loss, formation of fragments containing specific functional groups, and undesirable changes in the surface of polymeric films were limited in the presence of organotin complexes. Organotin complexes containing three phenyl groups showed the most desirable stabilization effect. These act as efficient primary and secondary photostabilizers, and as decomposers for peroxides. In addition, such an additive inhibits the dehydrochlorination process, which is the main cause of poly(vinyl chloride) photodegradation.