Low potential electrosyntheses of free‐standing poly(dibenzofuran) films in mixed electrolytes of boron trifluoride diethyl etherate and trifluoroacetic acid

Free‐standing poly(dibenzofuran) (PDBF) films were synthesized electrochemically by direct anodic oxidation of dibenzofuran in mixed electrolytes of boron trifluoride diethyl etherate (BFEE) containing certain amount of trifluoroacetic acid (TFA). The oxidation potential of dibenzofuran in pure BFEE was measured to be only 1.31 V versus saturated calomel electrode (SCE). This value was much lower than that determined in acetonitrile + 0.1 mol L^?1 TBATFB (2.14 V vs. SCE). The addition of TFA to BFEE can further decrease the oxidation potential of the monomer to 1.07 V versus SCE in the mixed electrolyte of BFEE + 30% TFA. PDBF films obtained from this medium showed good electrochemical behavior, good electrochromic properties, and good thermal stability with conductivity of 10⁰ S cm^?1. FTIR and ¹H NMR spectra showed that the polymer was grown mainly via the coupling of the monomer at C₍₃₎ C₍₁₀₎ or C₍₄₎ C₍₉₎ positions (Scheme 1). As‐formed PDBF films were partly soluble in tetrahydrofuran (THF) or chloroform. Fluorescent spectral studies indicated that either soluble or PDBF in solid state was a good blue light PDBF emitter. To the best of our knowledge, this is the first report that free‐standing PDBF films can be electrodeposited. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1125–1135, 2006     

Multiscale dewetting of triblock copolymer thin film induced by solvent vapor

Multiscale dewetting of poly(styrene‐b‐ethylene/butylenes‐b‐styrene) (SEBS) triblock copolymer thin films induced by volatile solvent vapor treatment were observed in this study. Film rupture occurred at first and produced macroscopic holes. Near‐regular droplets (which represented a compromise between complete disorder and perfect order) could be formed at the last stage. The mechanism of solvent‐driven dewetting was discussed by comparing with that of thermal‐induced dewetting. Similar to thermal‐induced dewetting, the block copolymer thin films initially break up through the nucleation of holes that perforated the films. The rapid growing holes became unstable and formed nonequilibrium fingering patterns. The films exhibit autophobic or autodewetting phenomena. The velocity of the holes growth was nearly a constant (3.3 μm/min). The stages of the dewetting were quite similar to that found for homopolymer and block copolymer thin films dewetting on solid or liquid substrates under thermal treatment. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 2874–2884, 2005     

Gas chromatography of manganese(II) and manganese(III) trifluoroacetylacetonates by the ligand vapour technique

The thermal properties and gas Chromatographie behaviour of manganese(II) and manganese(III) trifluoroacetylacetonates (TFA) were investigated by using the ligand vapour technique. The two chelates, Mn(TFA); and Mn(TFA)₃, can be quantitatively eluted on a mixed-liquid phase (1.9% OV-17 ÷ 0.1% PEG-20M) at column temperatures above 210°C and 130–150°C, respectively; Mn(TFA)₃ is completely converted to Mn(TFA)₂ by thermal dissociation at column temperatures above 180°C and completely eluted as Mn(TFA)₂ above 210°C. The chelates can be determined separately within errors of about 1% after a preliminary extraction.     

Thin films of PS/PS‐b‐pnipam and ps/pnipam polymer blends with tunable wettability

We developed thin films of blends of polystyrene (PS) with the thermoresponsive polymer poly(N‐isopropylacrylamide) (PNIPAM) (PS/PNIPAM) and its diblock copolymer polystyrene‐b‐poly(N‐isopropylacrylamide) (PS/PS‐b‐PNIPAM) in different blend ratios, and we study their surface morphology and thermoresponsive wetting behavior. The blends of PS/PNIPAM and PS/PS‐b‐PNIPAM are spin‐casted on flat silicon surfaces with various drying conditions. The surface morphology of the films depends on the blend ratio and the drying conditions. The PS/PS‐b‐PNIPAM films do not show an increase in their water contact angles with temperature, as it is expected by the presence of the PNIPAM block. All PS/PNIPAM films show an increase in the water contact angle above the lower critical solution temperature of PNIPAM, which depends on the ratio of PNIPAM in the blend and is insensitive to the drying conditions of the films. The difference between the wetting behavior of PS/PS‐b‐PNIPAM and PS/PNIPAM films is due to the arrangement of the PNIPAM chains in the film. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019 , 57, 670–679     

Structure and multiferroic properties of Bi<Subscript>5</Subscript>FeTi<Subscript>3</Subscript>O<Subscript>15</Subscript> thin films prepared by the sol–gel method

The Bi₅FeTi₃O₁₅ (BFTO) films of layered structure have been fabricated on Pt/Ti/SiO₂/Si substrates by the sol–gel method. The thermal decomposition behaviors of precursor powder were examined using thermo-gravimetric and differential scanning calorimeters analysis. The optimal heat treatment process for BFTO films were determined to be low-temperature drying at 200 °C for 4 min and high-temperature drying at 350 °C for 5 min followed by annealing at 740 °C for 60 min, which led to the formation of compact films with uniform grains of ~300 nm. The structural, surface topography, ferroelectric and magnetic properties of the films were investigated. The remnant polarization (2P _r) of BFTO thin films under an applied electric field of ~550 kV/cm are determined to be 67.5 μC/cm² . Meanwhile, the weak ferromagnetic properties of the BFTO films were observed at room temperature.     

Optimized analysis oftrans-octadecenoic acids in edible fats

Summary Trans fatty acids (TFA) in edible fats are of interest, since they are suspected to influence serum lipid levels. Thus, to estimate the atherogenic potency of edible fats a precise analytical method for the determination of TFA is required. The present study does not only aim at the quantitative analysis of total C18:1 TFA, but also at the determination of the isomeric pattern oftrans-octadecenoic acids in different fats. The combination of argentation TLC with high resolution gas chromatography allows the quantification of 10trans- and 9cis-octadecenoic acid peaks. This method can be applied to hydrogenated vegetable fats as well as to ruminant fats and tissue lipids from different species. Based on this two-dimensional chromatography the intake of single TFA isomers with food can be determined, which is of importance with respect to the hypothesis, that the negative metabolic activity originates only from certain isomers, and to the considerable variation of isomeric patterns in different edible fats. Based on the precise determination of the totaltrans-octadecenoic acid content in milk fats by TLC and GC, a formula has been derived by regression analysis, which allows the evaluation of total C18:1 TFA contents from a routine GC analysis. Though the 61 milk fats used covered a wide scope of feeding and lactation conditions, a correlation coefficient of 0.9991 was achieved.     

Orientation control in nanoparticle filled block copolymer cold zone annealed films

Nanoparticles provide an attractive route to modifying polymer thin film properties, yet controlling the dispersion and morphology of functionalized nanoparticle filled films is often difficult. Block copolymers can provide an ideal template for directed assembly of nanoparticles under controlled nanoparticle‐polymer interactions. Previously we observed that neat films of cylinder forming poly(styrene‐b‐methyl methacrylate) PS‐b‐PMMA block copolymer (c‐BCP) orient vertically with dynamic sharp thermal cold zone annealing (CZA‐S) over wide range of CZA‐S speed (0.1–10) μm/s. Here, we introduce a low concentration (1–5 wt %) of nanoparticles of phenolic group functionalized CdS (fCdS‐NP), to PMMA cylinder forming polystyrene‐b‐poly (methyl methacrylate) block copolymer (c‐BCP) films. Addition of the fCdS‐NP induces a vertical to horizontal orientation transition at low CZA‐S speed, V = 5 μm/s. The orientation flip studies were analyzed using AFM and GISAXS. These results confirm generality of our previously observed orientation transition in c‐BCP under low speed CZA‐S with other nanoparticles (gold [Au‐NP], fulleropyrrolidine [NCPF‐NP]) in the same concentration range, but reveal new aspects not previously examined: (1) A novel observation of significant vertical order recovery from 5–10% vertical cylindrical fraction at V = 5 μm/s to 46–63% vertical cylindrical fraction occurring at high CZA‐S speed, V = 10 μm/s for the fCdS nanoparticle filled films. (2) We rule out the possibility that a nanoparticle wetting layer on the substrate is responsible for the vertical to horizontal flipping transition. (3) We demonstrate that the orientation flipping results can be achieved in a nanoparticle block copolymer system where the nanoparticles are apparently better‐dispersed within only one (matrix PS) domain unlike our previous nanoparticle system studied. We consider facile processing conditions to fabricate functionalized nanoparticles filled PS‐PMMA block copolymer films with controlled anisotropy, a useful strategy in the design of next generation electronic and photonic materials. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 604–614     

Preparation of ultrathin films of aromatic polymides by vapor deposition polymerization from N-silylated aromatic diamines or aromatic tetracarboxylic dithioanhydride

A novel method for the preparation of ultrathin films of aromatic polyimides was developed through vapor deposition polymerization from combinations of monomer pairs of either N,N′-bis (trimethylsilyl)-substituted aromatic diamines and pyromellitic dianhydride or aromatic diamines and pyromellitic dithioanhydride. Both diamine component and tetracarboxylic dianhydride component were evaporated simultaneously at a stoichiometric molar ratio under vacuum, giving a deposited film on a substrate, which consisted of a polyamic acid derivative formed by the ring-opening polyaddition. The deposit was then converted to polyimide by thermal imidization at a relatively lower temperature, compared with a conventional method using the parent diamine and tetracarboxylic dianhydride. The properties of polyimide ultrathin films such as thermal stability, chemical resistance, and dielectric behavior were almost the same as those of the polyimide films prepared by a conventional method.     

Synthesis and self‐assembly of thermotropic block copolymer with long alkyl tethered cage silsesquioxane in the side chain

Thermotropic POSS‐containing poly(methacrylate) with long alkyl chain tethered polyhedral oligomeric silsesquioxane (POSS) in the side chain and the block copolymers (PMMA‐b‐PMAC11POSS) were developed by through living anionic polymerization. The resulting polymers indicated a phase transition temperature at 112 °C from spherocrystal to isotropic phase. The POSS‐containing polymer segments tended to form matrix of microphase‐separated nanostructures in the bulk even in the very low volume fraction, for instance, PMMA cylindrical nanostructure was obtained by PMMA₁₇₅‐b‐PMAC11POSS₁₁ (?_PMAC11POSS = 0.44). The control of thin film morphology was carried out by not only solvent annealing, but also thermal annealing, resulting in the formation of well‐ordered dot‐ and fingerprint‐type nanostructures. This is the first report in a series of POSS‐containing block polymers that are capable for thermal annealing to generate well‐ordered microphase‐separated nanostructures in thin films. The novel thermotropic POSS‐containing block copolymer offers a promising material for block copolymer lithography. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Carbon Aerogel Films Synthesized at Ambient Conditions

Carbon aerogels derived from organic sol-gel process and supercritical drying are novel porous materials with interconnect structures and higher electrical conductivity, which are considered to be ideal electrode materials for supercapacitors and rechargeable batteries. The objective of the research was to synthesize carbon aerogel films at ambient conditions. Resorcinol formaldehyde (RF) and carbon aerogel films have been produced with extremely high RC ratio (molar ratio of resorcinol to catalyst) followed by subcritical drying. The structure of the porous films was investigated using electron scanning microscope. The specific surface area was measured by using nitrogen adsorption (BET) and electrical conductivity was measured with four-probe method. It was found that with extremely high RC ratio, the porous structure of RF and carbon aerogel films can be controlled from micro to macro porous at ambient conditions. With respect to the application as electrodes for fuel cells, carbon aerogel films with different porous structures on the two surfaces have been also obtained through optimizing the sol-gel process.     

A New ‘Off–On’ System Based on Core-Substituted Naphthalene Diimide with Dimethylamine for Reversible Acid–Base Sensing

A new ‘Off–On’ system designed and synthesised by functionalisation of a naphthalene diimide (NDI) core with dimethylamine produces 4,9-bis(dimethylamino)-2,7-dioctylbenzo[lmn][3,8]-phenanthroline-1,3,6,8-(2H,7H)-tetraone, abbreviated as DDPT ( 1 ). DDPT 1 was synthesised using a simple strategy, namely aromatic nucleophilic substitution using Br₂-NDI with dimethylamine at 110 °C. DDPT was characterized by ¹H and ¹³C NMR spectroscopy, ESI mass spectrometry and elemental analysis. DDPT 1 was then used for optical studies through protonation of its dimethylamine core with trifluoroacetic acid (TFA), blue-shifting the absorption band from 600 nm to 545 nm in solution. Interestingly, the fluorescence of DDPT 1 is weak in solution with a quantum yield Φ=0.09, which is significantly enhanced to Φ=0.78 upon addition of TFA. The limit of detection (LOD) was determined to 2.77 nm . Furthermore, DDPT 1 can be used for naked eyed detection not only under UV light (365 nm) but also using visible light, as clear changes can be clearly seen upon addition of TFA. The binding constant of DDPT was calculated to 2.1×10⁻³ m ⁻¹. Importantly, DDPT 1 showed reversible switching by alternative addition of acid (TFA) and base (triethylamine) without loss of activity. Immobilised on paper, DDPT 1 can be used for strip-test sensing in which the colour changes from blue to reddish when expose to TFA vapours and reverse in the presence of triethylamine vapours.     

Alginate-magnesium aluminum silicate films for buccal delivery of nicotine

Sodium alginate-magnesium aluminum silicate (SA-MAS) dispersions with nicotine (NCT) were prepared at different pHs and characterized for the particle size and zeta potential, NCT adsorbed by MAS, and flow behavior before film casting. The physicochemical properties, NCT content, in vitro bioadhesive property, and NCT release and permeation of the NCT-loaded SA-MAS films were investigated. This study showed that incorporation of NCT into the SA-MAS dispersions caused a change in particle size and flow behavior and that NCT could be adsorbed by MAS. The formation of protonated NCT at acidic and neutral pHs could interact with negatively charged MAS via an electrostatic force, resulting in the formation of NCT-MAS flocculates/complexes that could act as microreservoirs in the films. The NCT-loaded SA-MAS films prepared at pH 5 yielded the highest NCT content due to non-significant loss of NCT during drying. Moreover, pH of the preparation also affected the crystallinity and thermal properties of the films. The NCT release and permeation across the mucosal membrane of the films could be described using a matrix diffusion controlled mechanism. In addition, the NCT-loaded SA-MAS films also possessed a bioadhesive property for adhesion to the mucosal membrane. This finding suggests that the NCT-loaded SA-MAS films composed of numerous NCT-MAS complexes as microreservoirs demonstrated a strong potential for use as a buccal delivery system.     

Electrochromic Properties of Peroxopolytungstic Acid Thin Films

Electrochromic thin films have been deposited from peroxopolytungstic acid aqueous solutions. These solutions are obtained via the dissolution of tungstic acid in hydrogen peroxide. The nature and properties of the films depend on the drying procedure. Amorphous films are formed upon fast drying. They exhibit good electrochromic properties but have to be heat treated in order to become insoluble. Crystalline films are formed upon slow drying. Their electrochromic properties are not very good but better amorphous or crystalline films are then obtained after a thermal treatment above 200°C. In both cases, the reversibility of lithium insertion is not good during the first cycles but improve significantly upon cycling. This should be due to the electrochemical reduction of peroxo groups.     

Silica aerogel–poly(ethylene‐co‐vinyl acetate) composite for transparent heat retention films

Poly(ethylene‐co‐vinyl acetate) (EVA) plastic films are widely used for solar coverings including photovoltaic modules and commercial greenhouse films, but are poor at controlling heat flow. In this work, silica aerogel (SA) nanogels were examined for preparing transparent heat retention EVA films that block far infrared spectra radiation to maintain heat, without compromising the optical performance of the films. SA nanogels were melt‐mixed using a mini twin‐screw extruder with EVA pellets to form SA/EVA composite, which were pressed into thin films with controlled thickness. The composite films were characterized in terms of optical properties using a variety of analytical methods including FTIR, UV–Vis spectroscopy, electron, confocal, and atomic force microscopy. Both thermicity and thermal conductivity of commercial and experimental SA/EVA films were measured. The results demonstrated that the SA/EVA films gave improved infrared retention compared to commercial thermal plastic films without compromising visible light transmission, showing the potential for this approach in next generation heat retention films. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014 , 52, 927–935     

新方法制备不溶性丝素薄膜及其性质研究

报道一种制备不溶性丝素蛋白薄膜的新方法.在温和搅拌下,将丝素溶液浓缩至16%,通过调整干燥温度和干燥速率,直接获得不溶于水的丝素薄膜.薄膜结构通过FTIR-ATR和XRD测定,同时对薄膜的机械性能进行研究.结果表明,丝素薄膜在干燥温度高于60℃时,有充足的β折叠结构存在,机械性能良好.当干燥温度为70℃时,材料的拉伸强度和断裂伸长率分别为29.8MPa和59.6%,远远强于经过甲醇处理的丝素薄膜的机械性能.当干燥温度高于60℃时,材料在水中具有优异的稳定性.由于在丝素薄膜的制备中避免了甲醇的使用并使材料具有更好的机械性能,此方法制备的丝素薄膜更为安全,应用会更广泛.     

SYNTHESIS AND CHARACTERIZATION OF PHTHALAZINONE POLY(ARYL ETHER SULFONE KETONE)WITH CARBONYL GROUP*

A kind of novel heat-resistant, high performance engineering thermoplastic phthalazinone poly(aryl ether sulfoneketone) (PPESK) containing a carboxyl group in its side chain was prepared by the nucleophilic displacement reaction of 4-(4-hydroxylphenyl)-1(2H)-phthalazinone with di(4-chlorophenyl) sulfone, 4,4'-difluoro-benzophenone and phenolphthalin insulfolane in the presence of K_2CO_3 to produce high molecular weight polymers which can be dissolved in some polarsolvents such as chloroform and nitrobenzene at room temperature and can be easily can into flexible, yellowish andtransparent films. PPESK is an amorphous polymer having a decomposition temperature above 400℃, which indicates that ithas high thermal stability. At the same time, the thermal properties of PPESKs with dicyandiamide (DICY) as curing agentindicated that the heat-resistance properties of the PPESKs are improved after curing. The apparent activation energy (ΔE) ofthe cross-linking reaction and the reaction order (n) of PPESK/DICY were found to be 52.2 kJ/mol and ca. 1.0, respectively.Therefore, the cross-linking reaction is approximately a first order reaction.     

An in situ GISAXS study of selective solvent vapor annealing in thin block copolymer films: Symmetry breaking of in-plane sphere order upon deswelling

Thin films of asymmetric poly(styrene-b-4-vinylpyridine) (PS-b-P4VP) block copolymers are studied by means of in situ grazing-incidence small-angle X-ray scattering (GISAXS) during solvent vapor annealing in tetrahydrofuran, a solvent selective for the PS majority block of the copolymer. Upon swelling, PS-b-P4VP block copolymers form hexagonal arrays of spherical P4VP microdomains in a PS matrix in films 7–9 layers thick. Deswelling the films induces a transition from hexagonal to face-centered orthorhombic (fco) symmetry, which is stable only at ∼7 layers of spherical microdomains. Dry films show co-existing hexagonal and orthorhombic symmetries when the solvent is removed slowly, whereas instantaneous solvent removal suppresses the fco structure, resulting in films with only hexagonal structure. The in-plane order of microdomains is significantly deteriorated in dry films independent of the solvent removal rate.Spherical block copolymer microdomains are known to undergo a transition from hexagonal to orthorhombic packing in isothermally annealed thin films when the number of sphere layers is increased from 4 to 5. In this paper, in situ GISAXS experiments reveal that a similar transition occurs during solvent vapor annealing in a selective solvent. Interestingly, the transition from hexagonal to orthorhombic packing of spheres occurs as solvent is removed from a thin block copolymer film. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016, 54, 331–338     

Synthesis and mechanochemical properties of biobased ABCBA-type pentablock copolymers comprising poly-d-lactide (A), poly-l-lactide (B) and poly(1,2-propylene succinate) (C)

The ABCBA pentablock copolymers (p-d -l -PPS) comprising poly(d -lactide) (PDLA: A), poly(l -lactide) (PLLA: B) and poly(propylene succinate) (PPS: C) were successfully synthesized by two-step ring-opening polymerization (ROP) of d - and l -lactide using a dihydroxy-terminated PPS as a macro-initiator. The pentablock copolymers revealed the high stereocomplex (sc) crystallinity, thermal stability and elastomeric property in their solution-cast films. It was found that the T_g was found to be proportional to the PPS content, whereas the T_m was proportional to their average block length. The thermal resistivity of the copolymer films was found to be as high as 202°C owing to their sc formation. The copolymers also showed improved stereocomplexibility compared to the enantiomeric mixtures of triblock copolymers (PLLA-PPS-PLLA and PDLA-PPS-PDLA) having similar PLLA and PDLA chain lengths. These pentablock copolymers can afford thermoplastic elastomers or flexible plastic materials having a 100% bio-based content, showing high heat-resistive property.     

Synthesis and morphology of all‐conjugated donor–acceptor block copolymers based on poly(3‐hexylthiophene) and poly(naphthalene diimide)

A series of all‐conjugated diblock and triblock copolymers comprised of poly(naphthalene diimide) (PNDI)‐based n‐type and the poly(3‐hexylthiophene) (P3HT) segments could be synthesized via the Kumada catalyst‐transfer polycondensation process. The crystalline structures and chain orientation of the block copolymer thin films were systematically studied by grazing incident wide‐angle X‐ray scattering (GIWAXS). The GIWAXS results indicated that both the P3HT and PNDI segments in the block copolymers form exclusive crystalline domains in which the P3HT domain aligns with an edge‐on rich orientation, and the PNDI domain aligns with a face‐on rich orientation. In contrast, the blend films of the P3HT and PNDI homopolymers also show two distinguished crystalline domains in which the P3HT domain aligns with an edge‐on rich orientation, and the PNDI domains align in different ways depending on the chemical structure of n‐type polymers, that is, PNDI1Th is isotropically dispersed, while PNDI2Th aligns with a face‐on rich orientation. In addition, the effect of thermal annealing on the crystalline behavior of the block copolymers is reported. The GIWAXS results indicated that thermal annealing increases the crystallinity of both segments without affecting their chain orientation. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 1139–1148     

Anisotropic thermal expansion behavior of thin films of polymethylsilsesquioxane, a spin-on-glass dielectric for high-performance integrated circuits

Thin films of poly(methylsilsesquioxane) (PMSSQ) are candidates for use as interdielectric layers in advanced semiconductor devices with multilayer structures. We prepared thin films of PMSSQ with thicknesses in the range 25.0-1151.0 nm by spin-casting its soluble precursor onto Si and GaAs substrates with native oxide layers and then drying and curing the films under a nitrogen atmosphere at temperatures in the range 250-400 degrees C. The out-of-plane thermal expansion coefficient alpha(perpendicular) of each film was measured over the temperature range 25-200 degrees C using spectroscopic ellipsometry and synchrotron X-ray reflectivity, while the in-plane thermal expansion coefficient alpha(parallel) of each film was determined over the temperature range 25-400 degrees C by residual stress analysis. PMSSQ films cured at higher temperatures exhibited reduced thermal expansion, which is attributed to the denser molecular packing and higher degree of cross-linking that arises at higher temperatures. Surprisingly however, all the PMSSQ films were found to exhibit very strong anisotropic thermal expansion; alpha(perpendicular) and alpha(parallel) of the films were in the ranges 140-329 ppm/ degrees C and 12-29 ppm/ degrees C respectively, depending on the curing temperature. This is the first time that cured PMSSQ thin films have been shown to exhibit anisotropic thermal expansion behavior. This anisotropic thermal expansion of the PMSSQ thin films might be due to the anisotropy of cross-link density in the films, which arises because of a combination of factors: the preferential orientation of methyl groups toward the upper film surface and the preferential network formation in the film plane that occurs during curing of the confined film. In addition, the film electron densities were determined using synchrotron X-ray reflectivity measurements and the film biaxial moduli were obtained using residual stress analysis.