Miscibility and hydrolytic degradation in alkaline solution of poly(l-lactide) and poly(p-vinyl phenol) blends

Poly(l-lactide) (PLLA) was melt-blended with poly(p-vinyl phenol) (PVPh) using a two-roll mill, and the miscibility between PLLA and PVPh and degradation of the blend films were investigated. It was found that PLLA/PVPh blend has miscibility in the amorphous state because only single T_g was observed in the DSC and DMA measurements. The T_g of the PLLA/PVPh blend could be controlled in the temperature range from 55 °C to 117 °C by changing the PVPh weight fraction. In alkaline solution, degradation rate of PLLA/PVPh blends was faster than that of neat PLLA because PVPh could dissolve in alkaline solution. The surface morphology of degraded PLLA and PLLA/PVPh blend were observed by SEM. The surface morphology of degraded PLLA/PVPh blend was finer than that of PLLA. Young's modulus of PLLA/PVPh blend increased with increasing PVPh content. Yield stress of PLLA/PVPh blends whose PVPh content was less than 30 wt% kept the level of about 55 MPa and that of PLLA/PVPh blend whose PVPh content was 40 wt% is much lower than that of neat PLLA.     

Phase behavior and interactions in blends of poly[(butylene adipate)-co-poly(butylene terephthalate)] copolyester with poly(4-vinyl phenol)

Miscibility with a linear T _g–composition relationship was proven for blend of poly(butylene adipate-co-butylene terephthalate) [P(BA-co-BT)] with poly(4-vinyl phenol) (PVPh). In comparison to the blends of PBA/PVPh and poly(butylene terephthalate) (PBT)/PVPh, the Kwei’s T _g model fitting on data for the P(BA-co-BT)/PVPh blend yields a q value between those for the PBA/PVPh and PBT/PVPh blends. The q values suggest that the interaction strength in the P(BA-co-BT)/PVPh blend is not as strong as that in the PBT/PVPh blend. Upon mixing the PVPh into the immiscible blend of PBA and PBT, the ternary PBA/PBT/PVPh blends only exhibits partial miscibility. Full-scale ternary miscibility in whole compositions is not possible owing to the significant ∆χ effect (χ _ij  – χ _ik ). The wavenumber shifts of the hydroxyl IR absorbance band indicates that the H-bonding strength is in decreasing order—PBT/PVPh > P(BA-co-BT)/PVPh > PBA/PVPh—and shows that the BA segment in the copolymer tends to defray interactions between P(BA-co-BT) and PVPh in blends.     

Effect of inert diluent segment on the miscibility behavior of poly(vinylphenol) with poly(acetoxystyrene) blends

Polymer blends of poly(vinylphenol) (PVPh) and poly(styrene‐co‐vinylphenol) with poly(p‐acetoxystyrene) (PAS) were prepared by solution casting from tetrahydrofuran solution. The thermal properties and hydrogen bonding of the blends were investigated by differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy. Although hydrogen bonding existed between the PVPh and PAS segments, the experimental results indicated that PVPh is immiscible with PAS as shown by the existence of two glass‐transition temperatures over the entire composition range by DSC. This phenomenon is attributed to the strong self‐association of PVPh, intramolecular screening, and functional group accessibility effects of the PVPh/PAS blend system. However, the incorporation of an inert diluent moiety such as styrene into the PVPh chain renders the modified polymer to be miscible with PAS. Copolymers containing between 16 and 51 mol % vinylphenol were fully miscible with PAS according to DSC studies. These observed results were caused by the reduction of the strong self‐association of PVPh and the increase of the interassociation between PVPh and PAS segments with the incorporation of styrene on the PVPh chain. According to the Painter‐Coleman association model, the interassociation equilibrium constant of PVPh/PAS blends was determined by a model compound and polymer blend. Good correlation between these two methods was obtained after considering the intramolecular screening and functional group accessibility effect in the polymer blend. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1661–1672, 2002     

Miscibility and interactions in blends of two proton‐donating polymers: Poly(acrylic acid)/poly(p‐vinylphenol) blends

Blends of poly(acrylic acid) (PAA) and poly(p‐vinylphenol) (PVPh) were prepared from N,N‐dimethylformamide (DMF) and ethanol solutions. The DMF‐cast blends exhibited single T_g's, as shown by modulated differential scanning calorimetry, whereas the ethanol‐cast blends had double T_g's. Fourier transform infrared spectroscopy showed that there was a specific interaction between PAA and PVPh in the DMF‐cast blends. The single‐T_g blends cast from DMF showed single‐exponential decay behavior for the proton spin–lattice relaxation in both the laboratory frame and the rotating frame, indicating that the two polymers mixed intimately on a scale of 2–3 nm. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 789–796, 2003     

Interactions and prediction of phase diagrams in ternary blends comprising poly(vinyl acetate), poly(vinyl p‐phenol), and poly(methyl methacrylate)

This study investigated and discovered a new miscible ternary blend system comprising three amorphous polymers: poly(vinyl acetate) (PVAc), poly(vinyl p‐phenol) (PVPh), and poly(methyl methacrylate) (PMMA) using thermal analysis and optical and scanning electron microscopies. The ternary compositions are largely miscible except for a small region of borderline ternary miscibility near the side, where the binary blends of PVAc/PMMA are originally of a borderline miscibility with broad T_g. In addition to the discovering miscibility in a new ternary blend, another objective of this study was to investigate whether the introduction of a third polymer component (PVPh) with hydrogen bonding capacity might disrupt or enhance the metastable miscibility between PVAc and PMMA. The PVPh component does not seem to exert any “bridging effect” to bring the mixture of PVAc and PMMA to a better state of miscibility; neither does the Δχ effect seem to disrupt the borderline miscible PVAc/PMMA blend into a phase‐separated system by introducing PVPh. Apparently, the ternary is able to remain in as a miscible state as the binary systems owing to the fact that PVPh is capable of maintaining roughly equal H‐bonding interactions with either PVAc or PMMA in the ternary mixtures to maintain balanced interactions among the ternary mixtures. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 1147–1160, 2006     

A novel synthesis of linear high-molecular-weight poly(4-vinylphenol) and poly[styrene-co-(4-vinylphenol)]

A novel synthesis of linear high-molecular-weight poly(4-vinylphenol) (PVPh) and poly[styrene-co-(4-vinylphenol)] (STVPh, 2 ) via demethylation reaction is developed. The parent polymers, poly(4-methoxystyrene) and poly[styrene-co-(4-methoxystyrene)] produced by free-radical polymerization, are converted to PVPh and STVPh ( 2 ), respectively, by being treated with trimethylsilyl iodide (TMSI) at room temperature. Both ¹H NMR and ¹³C NMR data show that methoxy is completely cleaved and converted to hydroxy after hydrolysis without crosslinking and other side reactions. In addition, size-exclusion chromatography data show that no chain scission occurs during group conversion.     

Complexation between poly(N,N-diethylacrylamide) and poly(acrylic acid) in aqueous solution

The complexation between poly(N,N-diethylacrylamide) (PDEA) and poly(acrylic acid) (PAA) in aqueous solution was studied by viscometric, potentiometric, and fluorescence techniques. It was found that an interpolymer complex formed between the two polymers through hydrogen bonding interactions with the stoichiometry of r=0.6 (r is unit molar ratio of PAA/PDEA), and the complex formation show the dependence on pH values. The phase behaviour studies showed that the lower critical solution temperature of the PDEA-PAA aqueous solution gradually increased with the increasing of r from 0.01 to 0.15, until a soluble system in the whole temperature region was obtained, which remained in the range of r=0.15-0.3. At higher PAA concentrations, when r is above 0.3, the system appeared phase separation, and almost no temperature dependence was observed. Based on these conclusion and structure characteristics of PDEA and PAA, a model containing only short sequences of monomer residues was proposed for the structure of PDEA-PAA complex.     

Novel miscible blends of poly(p-dioxanone) with poly(vinyl phenol)

Poly(p-dioxanone) (PPDO) has been blended with poly(vinyl phenol) (PVPh) and the PPDO/PVPh blends have been investigated using DSC, FTIR and POM. According to the single T_g criterion, miscibility has been found in the whole composition range for the blends obtained by solvent casting from dioxane solutions. The dependence of the T_g on composition shows negative deviation from the Fox equation. The interaction parameter, obtained from melting point depression analysis, χ₁₂ = ?1.0, confirms a thermodynamically miscible blend. Specific interactions have been analyzed by FTIR. The OH stretching region of PVPh indicates that upon addition of PPDO the hydroxyl–hydroxyl autoassociation interactions are mainly replaced by hydroxyl–carbonyl interassociation contacts, in detrimental of the possible hydroxyl–ether interactions. The carbonyl stretching region of pure PPDO is sensitive to intramolecular ether-ester interactions occurring in the oxyethanoate structures (–O–CH₂–CO–O–) present along the PPDO chain. The –O–CH₂–CO–O– structure presents only two minimum energy conformations, trans and cis, resulting in two different absorptions in the CO stretching region located respectively at about 1757 and 1732 cm^?1. Blending with PVPh promotes two new contributions red shifted by about 23 cm^?1 relative to the “free” CO components. Finally, POM analysis shows that the addition of PVPh to PPDO significantly decreases the crystallization rate of PPDO.     

Solid-State 13C-NMR detection of the isotropic carbonyl line shape in blends of poly(vinylphenol) with main-chain polyesters

The solid-state NMR isotropic line shape of the carbonyl ¹³C resonance is useful as a qualitative diagnostic probe of the polyester component′s morphology and molecular mobility in partially miscible blends with poly(vinylphenol), PVPh. The main-chain polyesters chosen for investigation in this study are poly(ethylene succinate), poly(ethylene adipate), poly(butylene adipate), and poly(caprolactone). A crystalline phase exists for polyester-rich mixtures in all cases. Verification of this claim is provided by DSC endothermic tran-sitions that map out melting point depression in the temperature-composition phase dia-grams. The carbonyl ¹³C-NMR signal in the crystalline domains exhibits a full width at half height of 1–2 ppm when the glass transition temperature of the blends is below the temperature of the NMR experiment. In all cases, a single concentration-dependent glass-transition temperature is measured by DSC, which increases monotonically from below ambient for polyester-rich blends to well above ambient for blends that are rich in poly(vinylphenol). When the concentration of the amorphous proton donor PVPh is suf-ficient to thwart crystallization of the polyester and increase the glass transition temperature of the blends above the temperature of the NMR experiment, the line width of the carbonyl resonance increases three- to fourfold to ca. 5–6 ppm. When the blends are completely amorphous and T_g is above ambient, the polyester carbonyl ¹³C line shape reveals at least two morphologically inequivalent microenvironments. A partially resolved carbonyl signal in rigid amorphous blends is (a) identified at higher chemical shift relative to the crystalline component, and (b) attributed to hydrogen bonding in the amorphous phase. This inter-action-sensitive hydrogen-bonded carbonyl signal accounts for an increasing fraction of the overall NMR absorption envelope of the carbonyl carbon site when the polyester is saturated with PVPh. The main-chain polyesters were chosen to probe the effect of chemical structure of the proton acceptor on the potential for hydrogen-bond formation. Aliphatic CH₂ spacers between the carbonyl groups dilute the concentration of interacting sites, and the dependence of the carbonyl ¹³C-NMR line shape on blend concentration reveals unique spectroscopic behavior in each of the four blend systems investigated. © 1993 John Wiley & Sons, Inc.     

Thermal degradation behaviour of poly(vinyl chloride) in the presence of poly(N′-acryloyl benzhydrazide)

The thermal degradation behaviour of poly(vinyl chloride), PVC, in the presence of poly(N′-acryloyl benzhydrazide), PABH, has been studied using continuous potentiometric determination of the evolved hydrogen chloride gas from the degradation and by measuring the extent of discoloration of the degraded samples. Blending this polymeric additive with dibasic lead carbonate, DBLC, reference stabilizer in different ratios had synergistic effects on both the thermal stability and the extent of discoloration of PVC.     

Water and drug transport in radiation-crosslinked poly(2-methoxyethylacrylate-co-dimethyl acrylamide) and poly(2-methoxyethylacrylate-co-acrylamide) hydrogels

Hydrogels of poly(N,N′-dimethylacrylamide-co-2-methoxyethylacrylate) and poly(acrylamide-co-2-methoxyethylacrylate) have been synthesized by radiation polymerization in dimethylformamide solution with trimethylolpropane trimethacrylate as a crosslinker. In this work, some investigations on the in vitro release of gentamicin sulphate, an antibiotic entrapped in the hydrogels, are reported. The kinetics of drug release from hydrogels matrices were examined and the results indicate that the release for the proposed geometry practically occurs in the first 24 h. The fractional cumulative release of the drug from the DMAA/MOEA matrices is linear when plotted against the square root of time, pointing out a Fickian process. On the other hand, AAm/MOEA matrices showed an initial non-Fickian behaviour, probably indicating a comparable rates of Fickian diffusion and polymer relaxation.     

Effects of lithium salt and poly(4‐vinyl phenol) on crystalline and amorphous phases in poly(ethylene oxide)

Effects of a strong‐interacting amorphous polymer, poly(4‐vinyl phenol) (PVPh), and an alkali metal salt, lithium perchlorate (LiClO₄), on the amorphous and crystalline domains in poly(ethylene oxide) (PEO) were probed by differential scanning calorimetry (DSC), optical microscopy (OM), and Fourier transform infrared spectroscopy (FTIR). Addition of lithium perchlorate (LiClO₄, up to 10% of the total mass) led to enhanced T_g's, but did not disturb the miscibility state in the amorphous phase of PEO/PVPh blends, where the salt in the form of lithium cation and ClO anion was well dispersed in the matrix. Competitive interactions between PEO, PVPh, and Li⁺ and ClO ions were evidenced by the elevation of glass transition temperatures and shifting of IR peaks observed for LiClO₄‐doped PEO/PVPh blend system. However, the doping distinctly influenced the crystalline domains of LiClO₄‐doped PEO or LiClO₄‐doped PEO/PVPh blend system. LiClO₄ doping in PEO exerted significant retardation on PEO crystal growth. The growth rates for LiClO₄‐doped PEO were order‐of‐magnitude slower than those for the salt‐free neat PEO. Dramatic changes in spherulitic patterns were also seen, in that feather‐like dendritic spherulites are resulted, indicating strong interactions. Introduction of both miscible amorphous PVPh polymer and LiClO₄ salt in PEO can potentially be a new approach of designing PEO as matrix materials for electrolytes. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 3357–3368, 2006     

Dielectric properties of poly(4‐vinylphenol) with embedded PbO nanoparticles

An organic/inorganic nanocomposite film was synthesized using poly(4‐vinylphenol) (PVPh) as an organic insulating polymer and PbO nanoparticles as a high‐k inorganic material to serve as an organic insulator with enhanced dielectric properties. PbO nanoparticles were dispersed into propylene glycol monomethyl ether acetate, and a solution of PbO/PVPh nanocomposite was prepared by adding a crosslinker. The PbO nanoparticle content within the PVPh polymer matrix was varied, and the effects of this variation upon the properties of the resulting nanocomposite films were studied, including the properties of surface morphology, surface bonding state and dielectric characteristic. The dielectric constant increased with increasing PbO content, reaching 9.2 at 1 MHz and with dielectric loss below 0.09 for the PbO content of 6 vol%. Furthermore, the leakage current increased to only 1.3 × 10^?8 A cm^?1 at the highest nanoparticle loadings, compared to the 7.2 × 10^?9 of pristine PVPh. The addition of PbO nanoparticles was found to effectively suppress the absorption of moisture on the surface of PbO/PVPh nanocomposite, although it also increased surface roughness, owing to the agglomeration and particulation of PVPh arising from an anchoring effect of the PbO nanoparticles. Copyright © 2015 John Wiley & Sons, Ltd.     

Organic-inorganic hybrid hydrogels based on linear poly(N-vinylpyrrolidone) and products of hydrolytic polycondensation of tetramethoxysilane

The initial stage of gelation of organic-inorganic hybrid hydrogels based on poly(N-vinylpyrrolidone) and the products of hydrolytic polycondensation of tetramethoxysilane has been studied by capillary viscometry. The development of strong bonds between polymer molecules and silica particles in aqueous solutions is proved by the electrokinetic sonic amplitude method. The molecular mass of poly(N-vinylpyrrolidone), the concentration of starting components, and their total amount affect the onset time of gelation in poly(N-vinylpyrrolidone)—water—tetramethoxysilane systems. The general scheme of formation of three-dimensional networks in such systems under the conditions of mutual penetration of poly(N-vinylpyrrolidone) coils is suggested. According to this scheme, nanoparticles of the general formula SiO _x (OH) _y (OR) _z linking poly(N-vinylpyrrolidone) macromolecules serve as junctions of the gel network due to the formation of hydrogen bonds between hydrogens of silanol groups of organosilanes and oxygens of carbonyl groups of poly(N-vinylpyrrolidone).     

Chemical modification of poly(vinyltrimethylsilane) and poly(1-trimethylsilyl-1-propyne) using highly reactive metallating systems

Poly(vinyltrimethylsilane) and poly(1-trimethylsilyl-1-propyne) are metallated using normal and secondary butyllithium chelate complexes with tetramethylethylenediamine and superbases based on complexes of normal and secondary butyllithium with potassium tert-pentoxide as metallating agents. Optimal conditions ensuring metallation of poly(vinyltrimethylsilane) and poly(1-trimethylsilyl-1-propyne) with a high yield without degradation of macrochains are determined. Poly(vinyltrimethylsilane) and poly(1-trimethylsilyl-1-propyne) are functionalized via reactions of metallated polymers with CO₂, trimethylsilyl chlorosulfone, diethyl disulfide, and ethylene oxide. COOH, SO₃H, OH, and thioester groups are introduced into poly(vinyltrimethylsilane), and SO₃H and COOH groups are incorporated into poly(1-trimethylsilyl-1-propyne). Upon introduction of carboxyl groups into poly(vinyltrimethylsilane), its hydrophilicity and permselectivity with respect to H₂O/N₂, H₂O/H₂, and H₂O/CH₄ pairs increase. The introduction of SO₃H groups into poly(1-trimethylsilyl-1-propyne) and poly(vinyltrimethylsilane) leads to the appearance of proton conductivity of these polymers.     

Thermal and spectroscopy studies on ternary miscibility and phase behavior in blends comprising poly(4‐vinyl phenol) and two aryl polyesters

Thermal analysis and Fourier transform infrared spectroscopy characterizations were performed on three ternary blend systems that comprise poly(4‐vinyl phenol) (PVPh) and any two of the three homologous aryl polyesters [poly(ethylene terephthalate) (PET), poly(trimethylene terephthalate) (PTT), and poly(butylene terephthalate) (PBT)]. Although PVPh is miscible with any one of the polyesters in forming a binary blend system, miscibility in ternary systems by introducing one more polymer of different structures to the blend system is not always expected. However, this study concludes that miscibility does exist in all these three ternary blends of all compositions investigated. Reasons and factors for such behavior were probed. Quantitative interactions in the ternary blend system were also estimated. The overall interaction energy density (B) by analysis of melting point depression for the PBT/PVPh/PET ternary blend system led to a negative value (B = −5.74 cal/cm³). Similarly, T_g‐composition analyses were performed on two other ternary blend systems, PET/PVPh/PTT and PTT/PVPh/PBT. Comparison of the qualitative results showed that the interaction energy densities in the other two ternary blend systems are similarly negative and comparable to the PBT/PVPh/PET ternary blend system. The Fourier transform infrared spectroscopy results also support the qualitative findings among these three ternary blend systems. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 1339–1350, 2006     

Photodegradation kinetics of poly(para-substituted styrene) in solution

The UV irradiation effects on stability of polystyrene, poly(4-methoxystyrene), poly(4-methylstyrene), poly(α-methylstyrene), poly(4-tert-butylstyrene), poly(4-chlorostyrene), and poly(4-bromostyrene) in dichloromethane, dichloromethane, tetrahydrofuran, and N,N-dimethylformamide solutions were studied in the presence of oxygen at different intervals of irradiation time. The photodegradation was studied at 293 K using fluorescence spectroscopy. Solutions of these polymers were accompanied by quenching of monomer and excimer emissions during the exposure of their solutions to UV light, and by a change in the structure of the fluorescence spectrum. Irradiation of poly(4-methylstyrene) and poly(α-methylstyrene) at excitation wavelength of 265 nm showed an increase of fluorescence intensity of a broad band, at longer wavelength without clear maxima. This may indicate that photodestruction of these polymers by irradiation with light of frequency absorbed by the polymer, may start from a random chain scission, with the possibility of formation of polyene and carbonyl compounds.     

Segmental and secondary dynamics in hydrogen‐bonded poly(4‐vinylphenol)/poly(methyl methacrylate) blends

Broadband dielectric spectroscopy was used to study the segmental (α) and secondary (β) relaxations in hydrogen‐bonded poly(4‐vinylphenol)/poly(methyl methacrylate) (PVPh/PMMA) blends with PVPh concentrations of 20–80% and at temperatures from ?30 to approximately glass‐transition temperature (T_g) + 80 °C. Miscible blends were obtained by solution casting from methyl ethyl ketone solution, as confirmed by single differential scanning calorimetry T_g and single segmental relaxation process for each blend. The β relaxation of PMMA maintains similar characteristics in blends with PVPh, compared with neat PMMA. Its relaxation time and activation energy are nearly the same in all blends. Furthermore, the dielectric relaxation strength of PMMA β process in the blends is proportional to the concentration of PMMA, suggesting that blending and intermolecular hydrogen bonding do not modify the local intramolecular motion. The α process, however, represents the segmental motions of both components and becomes slower with increasing PVPh concentration because of the higher T_g. This leads to well‐defined α and β relaxations in the blends above the corresponding T_g, which cannot be reliably resolved in neat PMMA without ambiguous curve deconvolution. The PMMA β process still follows an Arrhenius temperature dependence above T_g, but with an activation energy larger than that observed below T_g because of increased relaxation amplitude. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 3405–3415, 2004     

Synthesis and characterisation of poly(arylene sulphides)—Part II. Thermal analysis studies on poly(phenylene sulphide), poly(2-methyl phenylene sulphide), and poly(2,6-dimethyl phenylene sulphide) and related systems

Poly(p-phenylene sulphide), poly(2-methyl phenylene sulphide) and poly(2,6-dimethyl phenylene sulphide) have been subjected to comparative thermal analysis utilising thermogravimetry and isothermal weight loss studies in air and nitrogen. Comparative thermal stabilities have been evaluated and related to polymer structure. Activation energies for decomposition have been evaluated and are discussed.The related poly(p-phenylene sulphone) and poly(2-methyl phenylene sulphone) have also been studied and their behaviour analysed in the light of their possible formation during thermal oxidative degradation and air curing of the parent poly(phenylene sulphides).