4-vinylphenol Research Articles

Low-Power Flexible Organic Field-Effect Transistors with Solution-Processable Polymer-Ceramic Nanoparticle Composite Dielectrics.

Polymer-ceramic dielectric composites have been of great interest because they combine the processability of polymers with the desired dielectric properties of the ceramics. We fabricated a low voltage-operated flexible organic field-effect transistor (OFET) based on crosslinked poly (4-vinyl phenol) (PVP) polymer blended with novel ceramic calcium titanate nanoparticles (CaTiO3 NPs) as gate dielectric. To reduce interface roughness caused by nanoparticles, it was further coated with a very thin PVP film. The resulting OFET exhibited much lower operated voltage (reducing from –10.5 V to –2.9 V), a relatively steeper threshold slope (~0.8 V/dec) than those containing a pure PVP dielectric. This is ascribed to the high capacitance of the CaTiO3 NP-filled PVP insulator, and its smoother and hydrophobic dielectric surface proved by atomic force microscopy (AFM) and a water contact angle test. We also evaluated the transistor properties in a compressed state. The corresponding device had no significant degradation in performance when bending at various diameters. In particular, it operated well continuously for 120 hours during a constant bending stress. We believe that this technology will be instrumental in the development of future flexible and printed electronic applications.

Tuning the Wettability and Surface Free Energy of Poly(vinylphenol)Thin Films by Modulating Hydrogen-Bonding Interactions.

The ability to tune the surface properties of a polymer film in a simple and effective manner is important for diverse biological, industrial, and environmental applications. In this work, we investigated whether or not the surface free energy of poly(vinyl phenol; PVPh) can be tuned by adjusting the casting solvent and the thermal treatment time, which alters the proportions of intra-and intermolecular hydrogen bonding interactions. Compared to the untreated sample, in tetrahydrofuran (THF) system, the thermal treatment resulted in a lower proportion of intermolecular hydrogen bonds and a concomitant decrease in the surface free energy (from 39.3 to 18.8 mJ/m2). In contrast, the thermal treatment in propylene glycol methyl ether acetate (PGMEA) and ethyl-3-ethoxypropionate (EEP) systems increased the proportion of intermolecular hydrogen bonds and the surface free energy of the polymer thin films, from 45.0 to 54.3 mJ/m2 for PGMEA and from 45.5 to 52.9 mJ/m2 for EEP. Controlling intermolecular hydrogen-bonding interactions is a unique and easy method for tuning the surface free energies of polymer substances.

Characteristics of organic matter sources from Guadiana Estuary salt marsh sediments (SW Iberian Peninsula)

Estuaries are dynamic interfaces between land, rivers and the ocean that play major roles in the global carbon cycle. These coastal wetlands store huge amounts of organic carbon (OC), commonly known as “blue carbon” and excellent places to study C cycling. The Guadiana river estuary is among the most important tidal salt marshes in the South - Iberian coastal margin. Here, a detailed organic geochemical study is described that includes the identification of sedimentary OM composition at a molecular and isotopic level. Total organic carbon content (TOC) of core sediments ranged from 0.39 to 2.23% and stable carbon isotope composition (δ13C) also showed a wide range between −22.4 and −27.0‰. A13C depletion trend observed from the surface to bottom in the core sediments profiles, reflects loss of labile biogenic 13C enriched compounds i.e. polysaccharides and a selective preservation of more depleted compounds with depth i.e. lignin and lipids in the core sediments. Series of n-alkanes were found in the range from C10 to C31. Carbon preference index ratio (CPI) calculated for long-chain n-alkanes (C24–C31) that ranged between 1.17 and 1.94 reflecting diverse OM inputs to the sediments. A study of the lignin-derived phenolic composition pointed to a recalcitrant OM derived from both gymnosperm and angiosperm plants. Moreover, high abundance of vinyl phenol and vinyl guaiacol points to a dominant contribution of lignins from grasses and aquatic macrophytes to the sediments. A well-resolved series of long-chain linear alkyl benzenes (LABs from C4 to C22) were recorded in all core sediment samples indicating direct discharge of untreated domestic and/or industrial effluents to the estuary. Polycyclic aromatic hydrocarbons (PAHs) with more than 3 rings reflects the pyrogenic origin of a portion of the sedimentary OM. This study highlights the importance of different OM sources to the lower Guadiana estuarine sediments and contributes to a better knowledge about its origin, dynamics and fate.

PVP-SiO2 and PVP-TiO2 hybrid films for dielectric gate applications in CdS-based thin film transistors

We report a simple solution process to deposit organic-inorganic poly (vinyl phenol) (PVP)–SiO2 and PVP-TiO2 hybrid films. The spin dropped hybrid films were prepared at low-temperature and their main properties were studied by TGA, FE-SEM, AFM, FTIR, XPS and contact angle measurements. The results show that the surface of the PVP-SiO2 and PVP-TiO2 hybrid films is smooth with very low surface roughness of 0.25 and 0.51 nm, and surface energy of 48.4 and 40.1 mJ/m2, respectively. The electrical properties of the hybrid films, measured on MIM devices, show low leakage current density under 10−7 A/cm2 and dielectric constant of 5 and 4.6 at 1 kHz, respectively. The hybrid films were used as gate dielectric in solution-processed CdS thin film transistors (TFTs), showing diverse performance. The CdS/PVP-SiO2 devices showed high mobility of 18 cm2/Vs, on/off current ratio of 104, low threshold voltage of 0.6 V and subthreshold swing of 0.25 V/dec. Whereas, the corresponding values for the CdS/PVP-TiO2 ones were 0.45 cm2/Vs, 104, 1.9 V and 1.25 V/dec, respectively. The lower electrical performance of the CdS/PVP-TiO2 devices was attributed to the mismatching surface energies between the surfaces of the dielectric and semiconductor layers, and to the influence of a large number of trapped charges at this interface.

Multistage Resistive Switching Processes in Filament Conduction-Based Organic Memory Devices

The broken processes of carbon-rich conducting filament have been clarified in composite of [6, 6]-phenyl C61-butyric acid methyl ester (PCBM) and poly(4-vinyl phenol) (PVP) based resistive memory devices. Here, the multistage resistive switching processes in Al/PCBM + PVP/Al sandwich construction were reported, which exhibits a typical nonvolatile WORM storage effect, and these several states are well separated by a resistance ratio of 1: (5.01 × 101): (2.08 × 102): (5.45 × 102): (2.42 × 103). The Al/PCBM + PVP/Al memory devices feature multistate data storage, long retention time (1 × 105 s), and large memory window (maximum ON/OFF ratio, ∼104). Furthermore, conductance quantization during resistive switching processes was analyzed. This work might promote and improve the understanding and awareness of resistive switching mechanism for organic-based memory devices.

Molecular Docking Based Study and Analysis of Phytochemicals with TNF-α in Search of Anti-Inflammatory and Anticancer Agents

This study has investigated the possible mode of action of several phytochemicals known to possess anti-inflammatory and anti-cancer properties. It was found by molecular docking studies that ferulic acid, gallic acid, pcoumaric acid, vanillin, myrecene, 4-vinyl phenol and catechol interacted with the binding sight of TNF-α which is the chief regulator of inflammation. This study suggest a possible role of these phytochemicals as anticancer and anti-inflammatory agents.

Bamboo wastes catalytic pyrolysis with N-doped biochar catalyst for phenols products

Biomass catalytic pyrolysis for valuable O-containing chemicals is a promising approach for better utilization of oxygen in biomass resource, where the catalyst, with the properties of green, low cost, high activity and stability, is a critical point. In this study, we proposed a novel and green method to produce phenols through biomass (bamboo wastes) catalytic pyrolysis with N-doped biochar catalyst, which was investigated in a fixed bed reactor to explore the catalytic pyrolysis mechanism of N-doped biochar catalyst. N-doped biochar catalysts, with different nitrogen content and specific surface area, were by products came from biomass N-enriched pyrolysis. Results showed that N-doped biochar catalyst greatly promoted the generation of phenols (reached 82%), especially valuable 4-vinyl phenol with 31% content and 6.65 wt% yield, as well as 16% 4-ethyl phenol with 3.04 wt% yield, based on biomass. It also promoted aromatics formation, while inhibited the generation of O-species and acetic acid with more CO2 and H2O release, thus greatly improved bio-oil quality. Furthermore, N-containing groups in N-doped biochar catalyst showed good stability, while O-containing groups decreased largely. N-doped biochar mainly acted as adsorbent, catalyst, and reactant during catalytic pyrolysis, and the possible catalytic pyrolysis mechanism was proposed based on experiment results and quantum calculations. In conclusion, N-doped biochar catalyst showed excellent catalytic property for biomass catalytic pyrolysis for phenols products.

Functionalized Copolymers of Isobutylene with Vinyl Phenol: Synthesis, Characterization, and Property

The random copolymers of isobutylene (IB) with polar comonomers of 4-acetoxystyrene (ACS) or 4-tert-butoxystyrene (TBO), P(IB-co-ACS) and P(IB-co-TBO), could be successfully synthesized via cationic copolymerization with FeCl3-based initiating system. The kinetics of the cationic copolymerization process was in situ investigated by inserting a diamond probe into the reaction system by ATR-FTIR spectroscopy. The chemical structure and incorporation content of polar comonomers in the copolymers were characterized by GPC with RI/UV dual detectors and 1H-NMR spectroscopy. The corresponding functionalized random copolymers of IB with vinyl phenol P(IB-co-POH) carrying phenolic hydroxyl side groups could be further prepared via the complete hydrolysis of acetoxyl side groups in P(IB-co-ACS) or tert-butoxyl side groups in P(IB-co-TBO) copolymers. The functionalized P(IB-co-POH) copolymers became hydrophilic with water contact angle (WCA) of ca. 80° for the self-assembly in hot water, compared to the hydrophobic polyisobutylene with WCA of ca. 110°. The functionalized P(IB-co-POH) copolymers also displayed an excellent self-healing property due to the interaction of intermolecular hydrogen bonding and formation of three dimentional supramolecular networks from phenolic hydroxyl side groups. Furthermore, P(IB-co-POH) copolymers also provided a good matrix for the homogeneous dispersion for silica nanoparticles due to the formation of hydrogen bonding between copolymer chains and silica nanoparticles.

Nonvolatile WORM and rewritable multifunctional resistive switching memory devices from poly(4-vinyl phenol) and 2-amino-5-methyl-1,3,4-thiadiazole composite

A multifunctional resistive switching memory devices with the typical sandwich structure of Al/Poly(4-vinylphenol) (PVP)+2-Amino-5-methyl-1,3,4-thiadiazole/Al is fabricated. Al as the bottom and top electrodes is easy to realize by simple thermal evaporation process, and a PVP and 2-Amino-5-methyl-1,3,4-thiadiazole composite film as the active layer is prepared by sol-gel method and spin coating process. The as-fabricated resistive switching memory device shows write-once-read-many (WORM) and rewritable multifunctional memory behaviors, for the rewritable and WORM memory modes, the ON/OFF ratio is 104 and 80, respectively. The as-fabricated device shows tristable conductivity states which equivalent to “0”, “1” and “2”, and these three conductance states are steady under the constant voltage retention test, as well as during the endurance test, indicating advantageous features of stable operation and dependable endurance. It is noteworthy that the simple preparation process is expected to promisingly hold the post of industrialization low-cost preparation in future electronic devices for ternary data storage utilities.

Glass Transition Behaviors of Poly (Vinyl Pyridine)/Poly (Vinyl Phenol) Revisited.

We examined the composition and molecular weight dependence of the glass transition temperature in detail for two types of hydrogen bonding miscible blends: poly (2-vinyl pyridine)/poly (vinyl phenol) (2VPy/VPh) and poly (4-vinyl pyridine)/poly (vinyl phenol) (4VPy/VPh). Regarding the functional form of the glass transition temperature, Tg, as a function of the weight fraction, we found a weak deviation from the Kwei equation for 2VPy/VPh blends. In contrast, such a deviation was not observed for the 4VPy/VPh blend. By relating the difference in the functional forms of Tg between the two blend systems to the difference in hydrogen bonding ability, we proposed a modified version of the Kwei equation. As for the interaction parameter, q in the Kwei equation, clear molecular weight dependence was observed for 2VPy/VPh blends: the lower the VPh molecular weight in the oligomer level, the higher the q values, suggesting the higher hydrogen bonding formability near the polymer chain ends than the middle part of a polymer chain.

Efficient combination of Roll-to-Roll compatible techniques towards the large area deposition of a polymer dielectric film and the solution-processing of an organic semiconductor for the field-effect transistors fabrication on plastic substrate

Abstract Flexible Organic Field-Effect Transistors (OFETs) constitute nowadays a highly promising field of the organic and printed electronics due to their multiple applications (flexible displays, sensors etc.). However, their cost-effective fabrication by large area Roll-to-Roll compatible printing methods still remains a challenge for their integration to commercial products. In this work, the moderate speed (1 m/min) process of the flexible cross-linked Poly(4-vinyl phenol) (PVP) polymer gate dielectric layer was carried out by integrating a slot-die method that mimics the Roll-to-Roll (R2R) coating conditions, in combination to an airbrush spray method for the solution-processing of the 6,13-bis(triisopropylsilylethynyl)-pentacene (TIPS-PEN) organic semiconductor. Particularly, the PVP dielectric was slot-die-coated over a 90 × 15 cm2 substrate, while subsequently the TIPS-PEN semiconductor was sprayed onto the 15 × 20 mm2 cPVP-patterned plastic substrates. Α surface investigation study on the well-formed slot-die-coated cPVP strips was conducted, revealing desirable dielectric film topography as a result of the good control over the coating process. A detailed analysis of the cPVP thickness evolution along the 90 × 1.3 cm2 patterned stripe, was carried out. The morphological analysis of the sprayed TIPS-PEN layer over the cPVP film revealed well-organized large crystalline domains across the channel area, as a result of the sufficient crystallization time and the excellent cPVP surface morphology. The fabricated bottom gate/top contact flexible OFETs exhibited excellent I-V electrical characteristics with a maximum mobility of 0.21 cm2/V, negligible hysteresis, low threshold voltages (average value of −0.1 V) and on/off current ratios in the range of 103 to >104. These results demonstrate the potentiality of the proposed scalable methods for the large scale fabrication of high performance low-cost OFET devices.

Miscibility and Crystallization Behavior of Novel Branched Poly(ethylene succinate)/Poly(vinyl phenol) Blends

The blends of novel branched poly(ethylene succinate) (b-PES) and poly(vinyl phenol) (PVPh) were prepared via a solution and casting method. The miscibility, melting behavior, spherulitic morphology and growth, and crystal structure of b-PES/PVPh blends were investigated in detail. PVPh was miscible with b-PES over the whole compositions as evidenced by the single composition dependent glass transition temperature. Double melting behavior occurred in neat b-PES and b-PES/PVPh 85/15 blend after isothermal melt crystallization, which may be explained by the melting, recrystallization, and remelting mechanism. In addition, the depression of equilibrium melting point of an 85/15 blend was also found, confirming again the miscibility between the two components. The addition of PVPh caused the decrease of nucleation density and crystal growth rates of b-PES spherulites in the blend. The crystal structure of b-PES was unchanged before and after blending; moreover, the crystallinity of b-PES decreased slightly in the blend.

Proline-Mediated Knoevenagel–Doebner Condensation in Ethanol: A Sustainable Access to p-Hydroxycinnamic Acids

Naturally occurring p-hydroxycinnamic acids were obtained using an amine-and toxic solvent-free Knoevenagel-type pathway. This method uses not only non-toxic reagents (i.e., L-proline and magnesium oxide as catalyst) and ethanol as green solvent, all reagents and solvent being renewable and accessible at low price. By combinaing a Design of Experiment and a One Variobale At a Time optimization (OVAT), the different reaction parameters optimized in order to favor sinapic acid synthesis over that of the two other possible by-products, the corresponding di-acids and vinyl phenols. This alternative to classical Knoevenagel reaction allowed to substitute traditional pyridine-and piperidine-catalyzed pathway while obtaining each natural p-hydroxycinnamic acids in good conversions and yields (50-85%).

Oxygen additive effects on decomposition rate of poly(vinyl phenol)-based polymers using hydrogen radicals produced by a tungsten hot-wire catalyst

For fabricating semiconductor devices and for microelectromechanical systems, photoresists are important materials supporting photolithography processes. However, photoresists must be removed for subsequent processes. An earlier study demonstrated that adding a small amount of oxygen gas to the atmosphere in which hydrogen radicals are produced increased the decomposition rate of a positive-tone novolac photoresist. For this study, we prepared polymers with different side chain structures based on poly(vinyl phenol) (PVP). We examined the effects of added oxygen and the oxygen-added hydrogen radicals on the decomposition rates of PVP-based polymers. Hydroxyl groups of PVP are partly substituted with tert-butoxycarbonyl groups in order to use for base polymer of KrF photoresist. Results show that oxygen addition can be useful for KrF photoresist removal.

Miscibility of PEO-b-PCL and its Component Polymers with PVPh at the Air/Water Interface

The mixed monolayer behavior of polyethylene-block-polycaprolactone (PEO-b-PCL) and its component polymers (PEO or PCL) with poly(vinyl phenol)(PVPh) was investigated from the measurements of surface pressure-area per molecule (π-A) isotherms at three different temperatures(10˚C, 25˚C and 40˚C). The miscibility and nonideality of the mixed monolayers were examined by calculating the excess surface area as a function of composition. Interestingly, PEO and PCL were shown to have different interactions with PVPh at the air/water interface from in the bulk state on the solid substrate. PE O demonstrated mostly positive excess surface area with PVPh. Negative excess surface areas were in the majority observed in the PCL/PVPh monolayers. A scheme of differences in interaction sites between PEO (or PCL) and PVPh at the air/water interface was proposed to explain the negative or positive deviations of surface areas successfully.

Comparative study of pyrolysis characteristics of bamboo powder and grape vine by anaerobic fermentation pretreatment

To further explore the different effects of anaerobic fermentation on pyrolysis behaviors of grass and xylophyta, bamboo powder (BP) and grape vine (GV) were pretreated and pyrolysis characteristics were studied by thermogravimetric analysis (TG) and pyrolysis-gas chromatograph/mass spectrometry (Py-GC/MS) analysis. With the pretreatment time increasing from 0 to 20 days, cellulose contents in BP decreased from 51.47 to 48.52 wt.% and extractives contents increased from 5.58 to 11.57 wt.%. Only the extractives in GV were degraded during pretreatment. TG curves of BP moved to the higher temperature, which was contrary to that of GV. The residues at 700 °C from BP decreased from 25.11 to 16.9 wt.%, however that of GV increased. In the bio-oil of BP pyrolyzed at 500 °C, sugars contents firstly increased from 3.09 to 18.18% and then decreased; contents of linear acids and linear ketones decreased. The pretreatment improved significantly pyrolysis selectivity of BP for levoglucose (LG) and 4-vinyl phenol (4-VP). At 500 °C, LG content reached the maximum of 13.71% from the sample for 5 days. At 300 °C, 4-VP content reached the maximum of 16.16% from the sample for 20 days. Prolonging the pretreatment duration restrained the formation of LG and 4-VP. The bio-pretreatment increased the contents of linear carbonyls, linear acids and linear ketones in the GV bio-oil, but it decreased the sugars content especially LG.

Physical gelation of AB-alternating copolymers made of vinyl phenol and maleimide units: cooperation between precisely incorporated phenol and long alkyl pendant groups

Alternating copolymers of vinyl phenol and alkyl maleimide gave organogel in aromatic solvents. The gelation was induced by segregation.

Organic insulator layer influence on the electrical properties of N, N’-di (2-ethylhexyl) - 3, 4, 9, 10-perylene diimide organic thin-film transistors: Experiment and modeling

In this work, n- type organic thin film transistors (OTFTs) based on different kinds of organic dielectrics were fabricated, characterized and theoretically investigated. Three kinds of organic insulators were applied as dielectric gate which are: divinyl tetramethyl disiloxane-bis (benzo-cyclobutene) (BCB), poly(vinylalcohol) (PVA) and poly (4-vinyl phenol) (PVP). Analytical model was applied to describe the electrical behavior of the fabricated OTFTs and to explain the absence of saturation of the drain current for the device based on PVA dielectric. In addition, Meyer–Neldel rule-grain boundary model was applied for the calculation of total resistance of OTFTs based on different dielectrics materials. The theoretical results of output characteristics and total resistance showed an excellent agreement with the experimental measurements. The experimental and theoretical calculations revealed that the n-channel OTFTs based on BCB as an insulator layer exhibited superior electrical characteristics in terms of threshold voltage, mobility and drain current compared with the devices based on PVA and PVP as a gate insulator layer. The device based on BCB organic insulator layer has the largest mobility of 4 × 10−3 cm2 V−1 s−1, the smallest leakage current relative to the devices based on PVA and PVP. While, the device fabricated with PVP organic insulator gate has a large trap density on the PVP-EHPDI interface which causes a pronounced decrease in field effect mobility and consequently drain current.

Floating Drain-Based Measurement of ON-State Voltage of an OTFT for Sensing Applications

The threshold voltage of an organic thin-film transistor (OTFT) is sensitive to several variables, which makes it attractive for sensing applications. However, its measurement is not straightforward, especially, when mobility is gate voltage-dependent, and source and drain resistances are significant. The on-state voltage of a TFT does not suffer from these drawbacks, and thus, offers an alternative variable for use as a sensing variable. However, conventional measurement of on-state voltage marking the onset of conduction in the device requires measurement of very low current values, and extrapolation as a result of which it is not commonly employed. This paper demonstrates a simpler alternative method for measurement of on-state voltage that requires measurement of floating drain voltage as source voltage is linearly ramped while maintaining gate voltage constant. The drain voltage tracks the source voltage until the channel is completely removed. 2-D numerical simulation results are presented to validate that the proposed technique for the extraction of on-state voltage yields reliable estimates under different device conditions. Experimental results obtained with pentacene/poly (4-vinyl phenol)-based top contact bottom-gate OTFTs are also presented to illustrate the proposed concept.

Properties and surface morphologies of organic–inorganic hybrid thin films containing titanium phosphonate clusters

Organic–inorganic hybrid thin films containing [Ti4(μ3-O)(OiPr)5(μ-OiPr)3(O3PPh)3]·THF (TiOPPh) were prepared via the hybridization of TiOPPh with poly(vinyl phenol) (PVP), poly(styrene-co-allyl alcohol) (PSA), and poly(bisphenol A-co-epichlorohydrin) (PBE) using spin coating. These thin films were characterized in terms of their transmittance, pencil hardness, and surface morphologies. The transmittance values of the PVP hybrid thin films decreased with the addition of TiOPPh because of the formation of Ti–O–Ph bonds. The pencil hardness values of the hybrid thin films were in the order PVP > PBE > PSA hybrids. Using confocal laser scanning microscopy and atomic force microscopy, the pencil hardness values were determined to be strongly dependent on the surface morphology, such as the roughness and presence of pin holes. The model cluster was synthesized by the reaction of TiOPPh with excess ethanol to study the structures of the TiOPPh in hybrids. From the nuclear magnetic resonance spectroscopy and single-crystal X-ray structure analyses, the main core structure of the model cluster was found to retain the core structure of TiOPPh. Organic–inorganic hybrid thin films containing [Ti4(μ3-O)(OiPr)5(μ-OiPr)3(O3PPh)3]·THF (TiOPPh) as element blocks were prepared via hybridization with the hydroxyl-substituted organic polymers (PVP, PSA, or PBE) by spin-coating. The hybrid thin films were characterized by AFM, DSC, and pencil hardness. The pencil hardness values of the PVP hybrid thin films were in the order 20 > 40 > 0 wt% and were dependent on the surface smoothness. When TiOPPh was reacted with excess ethanol, the core was retained. Therefore, the core of TiOPPh will be retained in the hybrid polymers.