Synthetic thermally reversible gel systems. VIII. Poly(vinyl chloride)–dioxane

When interpreted by network theory, equilibrium swelling measurements on poly-(vinyl chloride) (PVC) film in dioxane and moduli measurements on the equilibrium swelled films yield values for the approximate molecular weight between thermally reversible crosslinks and for the number of these crosslinks per polymer chain. These values are in reasonable agreement with the thermodynamic analysis of PVC–dioxane gels by Takahashi, Nakamura, and Kagawa and with the premise that three-dimensional network formation in these gels occurs by crystallization of a very limited number of syndiotactic sequences per chain having a sequence length of between 8 and 10. Failure to observe fusion endotherms by DTA on PVC–dibutyl phthalate gels supports the view that PVC gels have a low crystalline crosslink density and a low heat of crosslinking. The heat of crosslinking obtained by the method of Eldridge and Ferry shows only moderate agreement with expectations based on the heat of fusion of PVC and the number of repeating units per PVC chain passing through a crystalline crosslink in a PVC–dioxane gel.     

Viscometric study of poly(vinyl chloride)/poly(vinyl acetate) blends in various solvents

The intermolecular interactions between poly(vinyl chloride) (PVC) and poly(vinyl acetate) (PVAc) in tetrahydrofuran (THF), methyl ethyl ketone (MEK) and N,N^′-dimethylformamide (DMF) were thoroughly investigated by the viscosity measurement. It has been found that the solvent selected has a great influence upon the polymer-polymer interactions in solution. If using PVAc and THF, or PVAc and DMF to form polymer solvent, the intrinsic viscosity of PVC in polymer solvent of (PVAc+THF) or (PVAc+DMF) is less than in corresponding pure solvent of THF or DMF. On the contrary, if using PVAc and MEK to form polymer solvent, the intrinsic viscosity of PVC in polymer solvent of (PVAc+MEK) is larger than in pure solvent of MEK. The influence of solvent upon the polymer-polymer interactions also comes from the interaction parameter term Δb, developed from modified Krigbaum and Wall theory. If PVC/PVAc blends with the weight ratio of 1/1 was dissolved in THF or DMF, Δb<0. On the contrary, if PVC/PVAc blends with the same weight ratio was dissolved in MEK, Δb>0. These experimental results show that the compatibility of PVC/PVAc blends is greatly associated with the solvent from which polymer mixtures were cast. The agreement of these results with differential scanning calorimetry measurements of PVC/PVAc blends casting from different solvents is good.     

Near infrared reflectance spectroscopy for the fast identification of PVC-based films

Near infrared (NIR) reflectance spectroscopy was used to develop a non-destructive and rapid qualitative method for the analysis of plastic films used by the pharmaceutical industry for blistering. Three types of films were investigated: 250 microm PVC [poly(vinyl chloride)] films, 250 microm PVC films coated with 40 g m(-2) of PVDC [poly(vinylidene dichloride)] and 250 microm PVC films coated with 5 g m(-2) of TE (Thermoelast) and 90 g m(-2) of PVDC. Three analyses were carried out using different pre-treatment options and a PLS (partial least squares) algorithm. Each analysis was aimed at identifying one type of film and rejecting all types of false sample (different thickness, colour or layer). True and false samples from four plastics manufacturers were included in the calibration sets in order to obtain robust methods that were suitable regardless of the supplier. Specificity was demonstrated by testing validation sets against the methods. The tests showed 0% of type I (false negative identification) and 1% of type II errors (false positive identification) for the PVC method, 13 and 3%, respectively, for the PVC-PVDC method and no error for the PVC-TE-PVDC method. Type II errors, mostly due to the slight sensitivity of the methods to film thickness, are easily corrected by simple thickness measurements. This study demonstrates that NIR spectroscopy is an excellent tool for the identification of PVC-based films. The three methods can be used by the pharmaceutical industry or plastics manufacturers for the quality control of films used in blister packaging.     

Effect of stabilizers in the thermal treatment of PVC—VII. An i.r. spectroscopic study of the association of stearic acid in PVC

Infrared spectra of PVC films containing 0.007-0.1 mol of stearic acid per 1 kg of PVC were measured in the range 1650–1850 cm^?1 at temperatures from 40 to 180°. In PVC, the association of stearic acid to dimers is reduced in comparison with paraffin wax. For concentrations 0.05-0.1 mol/kg PVC, 65–85% of stearic acid occurs as dimer at 40–70°; below 0.01 mol/kg, the proportion of dimers is under 50%. At the temperatures of the thermal treatment (150–180°), the monomer form of stearic acid predominates in PVC.     

PDMS migration at poly(vinyl chloride)/poly(ɛ-caprolactone)/poly(ɛ-caprolactone)-b-poly(dimethylsiloxane) blends surfaces

Films composed of poly(vinyl chloride)/poly(?-caprolactone)/poly(?-caprolactone)-b-poly(dimethylsiloxane) [PVC/PCL/(PCL-b-PDMS)] blends were prepared by solvent casting from tetrahydrofuran. The PVC content was kept constant (60 wt %) while varying the PCL and PCL-b-PDMS contents, part of the PCL (0–20 wt %) in the PVC/PCL (60/40) blend being replaced with PCL-b-PDMS with different molecular weights of the PCL blocks. The prepared blends were investigated by infrared spectroscopy and contact angle measurements. FTIR analysis and contact angle measurements indicate that the PDMS blocks tend to migrate towards the surface and this migration is preferential to the side in contact with air.     

Sum frequency generation and coherent anti-Stokes Raman spectroscopic studies on plasma-treated plasticized polyvinyl chloride films

Polyvinyl chloride (PVC) is a widely used polymer to which various phthalates are extensively applied as plasticizers. PVC materials are often treated with plasma to vary the hydrophobicity or for cleaning purposes, but little is known of the nature of the surface molecular structures after treatment. This research characterizes molecular surface structures of PVC and bis-2-ethylhexyl phthalate (DEHP)-plasticized PVC films in air before annealing, after annealing, and after exposure to air-generated glow discharge plasma using sum frequency generation (SFG) vibrational spectroscopy. In addition, we compare the vibrational molecular signatures on the surfaces of PVC with DEHP (at a variety of percent loadings) to those of the bulk detected using coherent anti-Stokes Raman scattering (CARS). X-ray photoelectron spectroscopy (XPS) and contact angle measurements have been used to analyze PVC surfaces to supplement SFG data. Our results indicate that DEHP was found on the surfaces of PVC films even at low weight percentages (5 wt %) and that DEHP segregates on surfaces after annealing. The treatment of these films with glow discharge plasma resulted in surface-sensitive reactions involving the removal of chlorine atoms, the addition of oxygen atoms, and C-H bond rearrangement. CARS data demonstrate that the bulk of our films remained undisturbed during the plasma treatment. For the first time, we probed the molecular structure of the surface and the bulk of a PVC material using combined SFG and CARS studies on the same sample in exactly the same environment. In addition, the methodology used in this research can be applied to characterize various plasticizers in a wide variety of polymer systems to understand their surface and bulk structures before and after systematic applications of heat, plasma, or other treatments.     

丙烯酸丁酯/4-乙烯基吡啶共聚物与聚氯乙烯共混相容性的研究

合成了系列丙烯酸丁酯/4-乙烯基吡啶共聚物[P(BAVP)].以四氢呋喃为溶剂,用溶剂浇铸法制备了一系列P(BAVP)与聚氯乙烯(PVC)的共混物.动态力学性能测试表明:共混物中吡啶环含量高于1%(摩尔百分含量)的共混物呈均相,即共聚物与PVC相容.P(BAVP)/PVC共混物的T_g随PVC含量和乙烯基吡啶链段含量增加而提高.由红外光谱分析推论出:P(BAVP)分子间的作用力比PBA分子间作用力弱,从而使P(BAVP)与PVC的相容性提高.     

Effect of humidity and solvent vapor phase on cellulose esters films

In the present study the effect of relative humidity (RH) during spin-coating process on the structural characteristics of cellulose acetate (CA), cellulose acetate phthalate (C-A-P), cellulose acetate butyrate (CAB) and carboxymethyl cellulose acetate butyrate (CMCAB) films was investigated by means of atomic force microscopy (AFM), ellipsometry and contact angle measurements. All polymer solutions were prepared in tetrahydrofuran (THF), which is a good solvent for all cellulose esters, and used for spin-coating at RH of (35 ± 5)%, (55 ± 5)% or (75 ± 5)%. The structural features were correlated with the molecular characteristics of each cellulose ester and with the balance between surface energies of water and THF and interface energy between water and THF. CA, CAB, CMCAB and C-A-P films spin-coated at RH of (55 ± 5)% were exposed to THF vapor during 3, 6, 9, 60 and 720 min. The structural changes on the cellulose esters films due to THF vapor exposition were monitored by means of AFM and ellipsometry. THF vapor enabled the mobility of cellulose esters chains, causing considerable changes in the film morphology. In the case of CA films, which are thermodynamically unstable, dewetting was observed after 6 min exposure to THF vapor. On the other hand, porous structures observed for C-A-P, CAB and CMCAB turned smooth and homogeneous after only 3 min exposure to THF vapor.     

Catalyzed degradation of poly(vinylchloride). III. Zinc(II) chloride catalysis

When PVC films containing zinc(II) chloride were heated in the temperature range 65–95°C, broad absorptions developed in the 250–900 nm region with maxima around 610 nm. The development of the color, the rate of which was proportional to the ZnCl₂ content, was preceded by an induction period, the length of which depended on the temperature. The activation energy of the process decreased as the ZnCl₂ content of the film increased. Color developments in air and in vacuum were compared.     

Properties of PVC. I. Properties of PVC films prepared by casting and by precipitation

This investigation compares the properties of PVC films prepared both by casting from tetrahydrofuran solution and from samples obtained by precipitation with properties of samples from the original PVC. The differences in properties are explained on the basis of solvent residues remaining in the samples even after tempering at higher temperatures and after extremely long times of drying. Attention was given to the difficulties caused by this fact, namely, in observing the influence of molecular weight and of distribution of molecular weights of fractions on PVC properties. Reasons were given for the retention of the tetrahydrofuran by PVC.     

Synthesis and optical properties of a poly(p‐phenylenevinylene) derivative and polyfluorenes with bipolar groups along the main chain

A poly(p‐phenylenevinylene) derivative (PPV–TPA)] and a series of statistical copolyfluorenes (PF–TPA)] containing oxadiazole and triphenylamine segments along the main chain were synthesized by the Heck reaction and nickel‐mediated coupling, respectively. The PF–TPA copolyfluorenes with relatively low contents of oxadiazole and triphenylamine units were readily soluble in common organic solvents, whereas the other copolyfluorenes displayed lower solubility. PPV–TPA showed excellent solubility in solvents such as tetrahydrofuran (THF), dichloromethane, chloroform, and toluene. Thin films of the polymers absorbed light in the range of 375–396 nm and had optical band gaps of 2.76–2.98 eV. They emitted blue‐green light with a maximum at 414–522 nm. The fluorescence quantum yields in THF solutions were 0.08–0.53. The copolyfluorene PF–TPA thin films with high contents of oxadiazole and triphenylamine moieties emitted pure blue light that remained stable even after annealing at 150 °C for 4 h in air. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3556–3566, 2006     

A facile approach to fabricate hierarchically structured poly(3‐hexylthiophene‐2,5‐diyl) films

Microstructured surfaces have great potentials to improve the performances and efficiency of optoelectronic devices. In this work, a simple robust approach based on surface instabilities was presented to fabricate poly(3‐hexylthiophene‐2,5‐diyl) (P3HT) films with ridge‐like/wrinkled composite microstructures. Namely, the hierarchically patterned films were prepared by spin coating the P3HT/tetrahydrofuran (THF) solution on a polydimethylsiloxane (PDMS) substrate to form stable ridge‐like structures, followed by solvent vapor swelling to create surface wrinkles with the orientation guided by the ridge‐like structures. During spin coating of the P3HT/THF solution, the ridge‐like structures were generated by the in‐situ template of the THF swelling‐induced creasing structures on the PDMS substrate. To our knowledge, it is the first report that the creasing structures are used as a recoverable template for patterning films. The crease‐templated ridge‐like structures were well modulated by the THF swelling time, the modulus of the PDMS substrate, the P3HT/THF solution concentration and the selective/blanket exposure of the PDMS substrate to O₂ plasma. UV–vis and fluorescence spectrometry measurements indicated that the light absorption and fluorescent emission were improved on the hierarchically patterned P3HT films, which can be utilized to enhance the efficiencies of organic solar cells. Furthermore, this simple versatile method based on the solvent swelling‐induced crease as the in‐situ recoverable template has been extended to pattern other spin‐coated films with different compositions. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017 , 55, 928–939     

Effect of stabilizers in the thermal treatment of PVC—X. An i.r. spectroscopic study of PVC with basic cadmium stearate

Infrared spectra (1900-1470 cm^?1) were studied for PVC films stabilized with basic Cd stearate and its mixture with stearic acid, after thermal degradation at 180° in air. Infrared spectroscopy makes it possible to follow the formation of Cd chloride-stearate on the basis of an absorption band at 1560–1565 cm^?1. The spectral data are compared with a potentiometric determination of HCl released from the mixture.     

Preparation of conducting poly(vinyl chloride)/polyindole composites and freestanding films via chemical polymerization

This study covers the synthesis of conducting polyindole (PIN) homopolymer, poly(vinyl chloride)/polyindole (PVC/PIN) composites, and preparation of their freestanding films. PIN and composites were synthesized chemically by radicalic mechanism using FeCl₃ as an initiator. Films of PVC and PVC/PIN composites were prepared by casting on glass Petri dishes. Mechanical properties of films were examined by stress–strain experiments. From FTIR spectra of polymers, it was revealed that polymerization reaction occurred by 2–3 mechanism. The conductivities of polymers at different temperatures were also measured by four‐probe technique and found in the range 10^?4 to 10^?5 S cm^?1. Magnetic properties of the polymers were analyzed by Gouy scale measurements and were found that their conducting mechanisms are of polaron and bipolaron natures. Thermal properties of polymers were investigated by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) and found that they had shown adequate thermal stability. X‐ray diffraction (XRD) spectra showed the amorphous nature of the polymers. Scanning electron microscopy (SEM) was used for microstructural analysis. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1290–1298, 2010     

Poly(vinyl chloride-g-butyl rubber)

The synthesis of poly(vinyl chloride-g-butyl rubber) and some of its physical properties are described. The key to the synthesis involves copolymerization initiation of an isobutylene–isoprene charge by a PVC/Et₂AlCl initiator system with 1,2-dichloroethane as solvent. The graft is a thermoplastic; cast films are flexible and optically clear. Proof of grafting is the crosslinking with S₂Cl₂ of the pentane-extracted product in THF solution. Crosslinking the butyl rubber moiety in the graft reduces overall stress properties.     

Synthesis and characterization of polyaniline-polyvinyl chloride blends doped with sulfamic acid in aqueous tetrahydrofuran

The temperature dependence of direct current (dc) conductivity was studied for various samples of polyaniline-polyvinylchloride (PANI-PVC) blended films. Polyaniline was doped with different concentrations of sulfamic acid in aqueous tetrahydrofuran (THF) and the blended films were prepared by varying the amount of doped PANI relative to a fixed amount of PVC. The dc conductivity of PANI-PVC blended films was measured to determine the effect of sulfamic acid (dopant) in the temperature range (300–400K). The mechanism of conduction is explained by a two-phase model. In order to evaluate the effect of the dopant, conductivity-derived parameters such as the pre-exponential factor (σ _o) and the activation energy (ΔE) were calculated. The structural changes of polyaniline-PVC blended films were characterized by FTIR spectroscopy that explores information about the suitability of the dopant in the chemical doping process.     

Small-angle x-ray and light scattering studies of the morphology of blends of poly(ϵ-caprolactone) with poly(vinyl chloride)

Solvent-cast films of blends of poly(?-caprolactone) (PCL) with poly(vinyl chloride) (PVC) were examined by low-angle x-ray scattering and by small-angle light scattering. X-ray scattering from crystalline compositions were analyzed using the Tsvankin–Buchanan technique and led to values of the repeat period of the lamellar structure and the thickness of the crystalline and amorphous layers. With increasing content of PVC, the amorphous layer thickness increased sufficiently to accommodate the PVC, leading to values of the linear crystallinity consistent with macroscopic measurements by density and DSC techniques up to about 50% PVC by weight. Above this concentration, the lamellar structure no longer appeared to be volume filling. At high concentration of PCL, the polymer consisted of volume-filling spherulites containing the lamellar substructure. Spherulite sizes were measured by light scattering and absolute light scattering intensities were consistent with calculations based upon the degree of crystallinity and anisotropy of the spherulites. Compositions containing more than 60% PVC were amorphous. Low-angle x-ray scattering was interpreted in terms of the Debye–Bueche theory which leads to values for a correlation distance l_c and the mean-square electron density fluctuation 〈η²〉 (which was also obtained from the invariant). By the method of Porod, the correlation distances were resolved into persistence lengths within the two phases, which were determined as a function of composition. The fluctuation 〈η²〉 was analyzed in terms of a two-phase model to show that its value was somewhat larger than would be obtained if the phases were composed of the pure components. It was not possible to uniquely determine their compositions. The data were consistent with the existence of a transition zone of the order of 30 Å thick between phases.     

Ruptured conjugated polymer thin films formed during spin coating

The formation of ruptured poly[2‐methoxy‐5‐(2′‐ethyl‐hexyloxy)‐1,4‐phenyl vinylene] (MEH–PPV) thin films coated from undried tetrahydrofuran (THF) solutions was investigated. Because of the incompatibility of water and MEH–PPV, the polymer films coated from THF/water solutions showed a ruptured film structure. In the photoluminescence (PL) spectra of the polymer thin films, the ruptured polymer films showed a redshifted emission in comparison with continuous polymer thin films. According to a comparison of the PL spectra of polymer solutions and films, MEH–PPV in THF showed a coil–cylinder transition during precipitation from solution. Because of the incompatibility of water and MEH–PPV, an increase in the water content could increase the ratio of polymer chains in the cylinder conformation, resulting in a redshifted emission for the films. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 79–84, 2006     

Investigation into new materials for optical devices: the miscibility and solvent effects of azobenzene derivative blends

With the increasing demand for novel devices with optical applications the search for new materials to data store and process becomes a priority. By introducing blends, tailor made properties and low cost give added advantage. Miscibility is an essential requirement for a new material, this research thus involves miscibility studies of poly(4‐(N‐(2‐methacryloyloxyethyl)‐N‐ethylamino)‐4′‐nitroazobenzene)₉₀‐co‐(methyl methacrylate)₁₀, (azobenzene derivative) with polymethyl‐methacrylate (PMMA), polyvinylacetate (PVAc) and polyvinylchloride (PVC) prepared in tetrahydrofuran (THF), and/or dimethylformamide (DMF) and/or dichloromethane (CH₂Cl₂). The glass transitions, solvent and varying molecular weight effect were investigated, since these all primarily influence the miscibility. THF was found to encourage miscibility at specific compositions of PVAc and PVC blends. However, with CH₂Cl₂ and DMF immiscibility is encouraged. The Fox–Flory equation was applied to the blends analyzing the PVC blends in DMF as deviations from ideality. Different molecular weights of PMMA were identified as immiscible regardless of solvent. PMMA's lower solubility in THF and CH₂Cl₂ compared to the azobenzene derivative, displayed the existence of PMMA islands. In all blends the favorable and unfavorable interactions between polymer–solvent–polymer systems are considered. Furthermore, the miscibility effect on increasing the MMA content of the azobenzene derivative was also investigated. Copyright © 2002 John Wiley & Sons, Ltd.     

Photocrosslinking of poly(2,3-epithiopropyl methacrylate) by the oxidation of pendant episulfide groups

In the photocrosslinking of poly(2,3-epithiopropyl methacrylate) (PETMA) films the effect of the pendant episulfide group's oxidation on the crosslinking of PETMA was investigated. Thermal crosslinking of PETMA is promoted by peroxides such as benzoyl peroxide and hydrogen peroxide. IR spectrum of the crosslinked PETMA showed that the reaction proceeded through the oxidation of episulfide groups by the peroxides. The anthracene (An) sensitized photocrosslinking of PETMA films also proceeded via the oxidation of episulfide groups by singlet oxygen. It was found that residual tetrahydrofuran (THF) in the films remarkably increased the rate of the photocrosslinking and/or reduced the induction period. From the further investigation concerning casting solvents it was found that residual CS₂, CCl₄, and CHCl₃ in films increased the rate of the photocrosslinking and/or reduced the induction period of the photocrosslinking. The disappearance rate of An in the films was also increased by the presence of residual CS₂, CCl₄, and CHCl₃, differring from the result of THF. These results were explained by a difference in lifetime of singlet oxygen in the films. From the results were explained by a difference in lifetime of singlet oxygen in the films. From the results concerning the effects of hydroperoxides such as THF hydroperoxide and t-butyl hydroperoxide on the photocrosslinking of PETMA films the acceleration effect of the residual THF was deduced to be due to the promotion of singlet oxygen-oxidation of sulfide groups by protic compounds such as THF hydroperoxide and H₂O in the THF.