Thermal Crosslinking Reaction Research Articles

Polymer gel electrolytes prepared from P(EG‐co‐PG) and their nanocomposites using organically modified montmorillonite

AbstractPolymer gel electrolytes were prepared by thermal crosslinking reaction of a series of acrylic end‐capped poly(ethylene glycol) and poly(propylene glycol) [P(EG‐co‐PG)] having various geometries and molecular weights. Acrylic end‐capped prepolymers were prepared by the esterification of low molecular weight (Mn: 1900–5000) P(EG‐co‐PG) with acrylic acid. The linear increase in the ionic conductivity of polymer gel electrolyte films was observed with increasing temperature. The increase in the conductivity was also monitored by increasing the molecular weight of precursor polymer. Nanocomposite electrolytes were prepared by the addition of 5 wt % of organically modified layered silicate (montmorillonite) into the gel polymer electrolytes. The enhancement of the ionic conductivity as well as mechanical properties was observed in the nanocomposite systems. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 894–899, 2004

Effects of Crystal Growth Conditions on Morphology of Crystalline Syndiotactic 1,2-Polybutadiene

The crystalline syndiotatic 1,2-polybutadiene was synthesized with a catalyst consisting of iron acetylacetonate (Fe(acac)3)-triisobutylaluminum (Al(i-Bu)3)-diethyl phosphite (DEP), and the effects of crystal growth conditions on morphology of thin films of the polymer were investigated by transmission electron microscopy (TEM) and electron diffraction (ED) techniques. The polymer with melting point 179 °C was found to have 89.3% 1,2-content and 86.5% syndiotacticity by 13C NMR measurement. The results of electron microscopic studies indicate that the solution-cast thin films of the syndiotatic 1,2-polybutadiene consist of lath-like lamellae with the c-axis perpendicular to the film plane, while a- and b-axes are in the film plane. The morphology of isothermally crystallized thin films of the polymer is temperature dependent. At lower crystallization temperatures (130 °C), a spherulitic structure consisting of flat-on lamellae is formed. With an increase in the crystallization temperature (e.g., at 140 °C), the spherulites and single faceted crystals coexist. At higher crystallization temperatures (150 °C), single crystals with a hexagonal prismatic shape are produced. When the crystallization temperature is above 155 °C, no crystalline structure is observed because of the thermal cross-linking reaction of the double bonds. The melt-draw films contain highly oriented lamellae with its growing direction perpendicular to the drawing direction. According to the orthorhombic packing of planar zigzag chains, the unit cell parameters calculated from the electron diffraction patterns are a = 1.102 nm, b = 0.664 nm, and c = 0.513 nm.

Gradient structure materials from homogeneous system induced by UV photopolymerization

This work deals with the synthesis of a gradient structure material from a homogeneous system of monomers. This new synthesis involved hydroxyethylmethacrylate, a hydroxytelechelic polybutadiene, and 4,4′-methylene-bis(cyclohexylisocyanate). These materials were made in two steps. The first one consisted in creating a photopolymerization gradient in methacrylic double bonds under UV exposure thanks to the decay of UV light intensity through the sample thickness. The second one involved a thermal crosslinking reaction leading to the formation of a polyurethane network in order to set the obtained gradient. Using FTIR and UV spectroscopies, the required experimental conditions to obtain and keep the gradient were investigated. Thus, these parameters enabled us to obtain a 20% hydroxyethylmethacrylate double bonds conversion gradient in the ultimate 5 mm thick material. Further DMA analysis well revealed a difference of structures between the two sides of the material.

Dot formation with 170-nm dimensions using a thermal lithography technique

We have developed a lithographic technique called ‘Thermal Lithography’ for application during the mastering process of ultra-high density optical disks. A Gaussian distribution of light intensity in a focused laser spot produces a spatially confined hot area that is of far smaller size than the laser spot size. The hot area induces a thermal cross-linking reaction in photoresist film, with the result that minute structures are fabricated after development. In this paper, we describe the use of this technique to fabricate 170-nm size dots in a photoresist film, each separated by a distance of 200 nm, shorter than the diffraction limit of 310 nm given by our optical set-up. We also confirmed that the size and height of the dots are approximately proportional to the incident laser power.

Thermal lithography for 0.1 μm pattern fabrication

Abstract We have succeeded in patterning narrow lines and dots with 100 nm dimensions in a photoresist film by a ‘thermal lithography’ technique using a semiconductor laser with 635 nm wavelength. The demonstrated resolution of the patterns produced is far beyond the diffraction limit of 530 nm given by our optical set-up. We utilized a focused laser spot, which approximately has a Gaussian profile in its light intensity distribution, to produce a spatially confined hot area in a phase change recording layer on a conventional polycarbonate optical disk. This hot area induced a thermal cross-linking reaction in an adjacent photoresist film. By optimizing the sample rotation speed and the laser power, we were able to confine the area where the thermal cross-linking reaction in the photoresist occurred and patterned extremely fine structures.

Thermal crosslinking of acetylene-containing polymers obtained by radical polymerization of aromatic enynes

Acetylene-containing polymers, obtained by the radical polymerization of 4-substituted aromatic enynes, were subjected to the thermal crosslinking reaction on the basis of the reactivity of the acetylene moieties. The crosslinking occurred from ca. 140°C to give an insoluble product. The crosslinking was supposed to be the irreversible reaction of the acetylene moieties to give new conjugated structure from the IR and UV–vis spectra. The steric bulkiness of the substituents tend to restrain the crosslinking and decline the decomposition temperature of the polymers.

Study on thermal crosslinking reaction of o-naphthoquinone diazides and application to electrodeposition positive photoresist

The thermal reactions of o-naphthoquinone diazide (NQD) compounds as a material for photoresists were studied in comparison with their photochemical reactions. An NQD compound decomposed at around 140°C and further reacted in the presence of an alcohol in the solution to yield an indenecarboxylic ester. The photochemical reaction of the NQD compound with alcohol also provided the same ester in a solution, as expected. In a polymer matrix, the thermal reaction of a multifunctional NQD compound with a copolymer having hydroxyl groups yielded sufficiently crosslinked structures at 140°C in 10 min. On the other hand, when the copolymer matrix containing the NQD compound was exposed to UV, and subsequently to heating (140°C for 10 min), no crosslinked structure was obtained. Consequently, it was confirmed that the heating provides a large difference in solubility between unexposed and exposed areas, quite a useful feature from the viewpoint of efficient development of photoimage. We have applied this finding to an electrodeposition positive photoresist incorporating a post exposure bake (PEB) in resist processing. The PEB afforded a very wide process window in an alkaline developer.

Crosslinkable maleimide copolymers for stable NLO properties

Second-order, nonlinear optical polymers based on epoxy-substituted methylvinylisocyanates and N-substituted maleimides were synthesized and characterized with spectral and thermal analysis. The photocrosslinking and thermal-crosslinking reactions of copolymers with different chromophore contents were studied. Thermally induced crosslinking during the poling process, performed at the glass-transition temperature (Tg), was prevented by Tg being decreased through the addition of a plasticizer. Electrooptic coefficients (r33), measured for crosslinked and noncrosslinked systems, had similar absolute values and relaxation dynamics. This behavior was explained in terms of the similar rotational mobility of the chromophore units and the paucity of crosslinking sites. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1589–1595, 2001

Three-component photoresists containing thermally crosslinkable vinyl ether derivatives

Poly(4-hydroxystyrene-co-4-methoxystyrene) (MEOST) was synthesized and MEOST-13 with the methoxystyrene content of 12.5 mol % was used as a binder polymer for a three-component photopolymer system. The MEOST-13 films containing a vinyl ether monomer and a photoacid generator are insolubilized in an aqueous base in a prebake step owing to the thermal crosslinking reaction between hydroxyl groups of MEOST-13 and vinyl ether groups. Upon exposure to light and subsequent postexposure bake, the crosslinks are decomposed by photogenerated acids, leading to effective solubilization of the exposed areas. The MEOST-13 films showed sufficient insolubilization at baking temperatures of 140°C or above. The conversion of vinyl ether groups increased rapidly with increasing baking temperature. The sensitivity of the MEOST-13 films increased abruptly with an increase in postexposure bake temperature because of the nature of chemical amplification. The MEOST-13 films showed a sensitivity of 33 mJ/cm2 and afforded positive-tone images with the improved resolution of 0.30-μm line and space at 248-nm light. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 3399–3404, 2001

THREE-COMPONENT PHOTORESISTS CONTAINING VINYL ETHER CROSSLINKING AGENTS

Thermal crosslinking reactivity and lithographic performance were investigated for three-component photoresists composed of a Brønsted acid-based binder polymer, a vinyl ether monomer as a crosslinking agent, and a photoacid generator. Poly(p-hydroxystyrene) (PHS) and poly(styrene-co-acrylic acid) (PST/PAA) were used as the binder polymers. The resists acted as highly sensitive, chemically amplified resists based on thermal crosslinking between a binder resin and a vinyl ether monomer and subsequent acidolytic cleavage of the crosslinks. The rate constants and activation energies for the thermal crosslinking reactions were determined, and the resists based on PST/PAA showed higher thermal crosslinking reactivity than PHS resists. The resists in this study exhibited high photosensitivity and afforded positive-tone images by alkaline development.

Two-component photoresists containing thermally crosslinkable photoacid generators

Bis{4-[2-(vinyloxy)ethoxy]phenyl]-4-methoxyphenylsulfonium triflate (TPS-2VE-Tf) and tris{4-[2'-(vinyloxy)ethoxy]phenyl}sulfonium triflate (TPS-3VE-Tf) were synthesized as thermally crosslinkable photoacid generators (PAGs) and used in a two-component chemically amplified photoresist system. The photoresist films formulated with poly(p-hydroxystyrene) (PHS) as a binder polymer and a thermally crosslinkable PAG are insolubilized in aqueous base by prebaking due to the thermal crosslinking reaction between PHS and the PAG. The insolubilization temperature of the resists and conversion of vinyl ether groups are greatly influenced by the PAG concentration and prebaking temperature, respectively. Upon exposure to deep UV and subsequent postexposure bake, the crosslinks are cleaved by photogenerated acid, leading to effective solubilization of the exposed areas. Photoresists containing TPS-2VE-Tf and TPS-3VE-Tf exhibited sensitivities of 12 and 45 mJ/cm 2 , respectively. Positive-tone images were obtained using a 2.38 wt% aqueous tetramethylammonium hydroxide developer.

A Tetramethylbiphenyl Poly(benzobisthiazole): Synthesis, Chracterization, Fiber Spinning, and Properties

Poly(benzobisthiazole)s containing an o-tetramethyl substituted biphenyl moiety were synthesized based on 2,5-diamino-1,4-benzenedithiol dihydrochloride and 2,2‘,6,6‘-tetramethylbiphenyl-4,4‘-dicarbonyl chloride. Homopolymerization of the two monomers and copolycondensation of the two monomers with terephthaloyl chloride were carried out in poly(phosphoric acid) (PPA). The interfacial polymerization technique was used to enhance the formation of a homogeneous liquid crystalline polymer solution suitable for fiber spinning. Copolymers of tetramethylbiphenyl PBZT/PBZT (25/75) were successfully spun into fibers from liquid crystalline solutions in PPA. Fibers were thermally cross-linked between 500 and 550 °C. The thermal cross-linking reaction was studied by thermogravimeteric analysis and by 13C solid-state NMR spectroscopy. Fiber morphology and properties are also reported and discussed.

Study on Photobase Generation from .ALPHA.-Aminoketones: Photocrosslinking of Epoxides with Carboxylic Acids.

It was demonstrated that α-aminoketones work effectively as photobase generators in epoxy-based compositions. After irradiation they accelerate the thermal crosslinking reaction of phenol novolac epoxy resin with polyacrylate having carboxylic acid groups despite of their high latency before irradiated. The acceleration effect depends on the structure of the photogenerated amines. Conformational calculations of the α-aminoketones and the related compounds suggest that folded conformations contribute to the latency of the amine moiety. In the conformations, the bulky benzoyl group of the aminoketone shields the amino nitrogen from acidic species present in the composition. By irradiation, the benzoyl part is cleaved and the active tertiary amine base with small substituents is eventually liberated. The investigation using model amines supported the explanation. The compositions used for this study can be utilized in the base-catalyzed imaging applications.

Condensation of Substituted Phenols with Hexakis(methoxymethyl)melamine: Synthesis, Characterization, and Properties of Substituted 2,4,6-Tris[3,4-dihydro-1,3-(2H)-benzoxazin-3-yl]-s-triazine Derivatives

Condensation of hexakis(methoxymethyl)melamine (HMMM) with 2,4-disubstituted and 4-substituted phenols in refluxing p-xylene catalyzed by dinonylnaphthalenedisulfonic acid (DNNDSA) gives substituted 2,4,6-tris[3,4-dihydro-1,3-(2H)-benzoxazin-3-yl]-s-triazine derivatives (1−4). These tris(benzoxazine) derivatives are characterized by infrared, 1H and 13C NMR, mass spectroscopy, and elemental analysis. Differential scanning calorimetry (DSC) studies suggest thermal cross-linking reactions of benzoxazines made from 4-substituted phenols but not for the one made from a 2,4-disubstituted phenol.

Crosslinking reaction of glycidyl methacrylate copolymers containing oxime-urethane groups using photogenerated pendant amines

Copolymers containing epoxy and oxime-urethane groups were prepared by copolymerization of glycidyl methacrylate (GMA) and benzophenone oxime allylurethane (BAU). The physical properties of these copolymers were characterized by GPC, NMR and DSC analyses. Photo-crosslinking reaction of the copolymers were studied by measuring the insoluble fraction of copolymer films under various reaction conditions. The degree of cross-linking reaction increased with irradiation time, heating temperature and the amount of BAU units in the copolymer. UV and IR absorption spectral studies indicate that thermal cross-linking reaction of the copolymer was catalyzed by the pendant photogenerated amines.

Physical properties and doping characteristics of polyaniline-nylon 6 composite films

Poly(aniline)-nylon 6 composite film (PANI-N) prepared by diffusion and chemical oxidative polymerization has very low percolation threshold contents (∼4 wt%) and provides a high conductivity. Hydrogen bonding between poly(aniline) (PANI) and nylon 6 is found to affect the doping characteristics of PANI-N. From the results of dynamic mechanical thermal analysis, the crystalline regions of nylon 6 in the composites are found to be affected by the formation of PANI. From u.v.-visible spectra, it is considered that the thermal cross-linking reaction of PANI may be reversibly changed by the chemical doping and de-doping processes. © 1997 Elsevier Science Ltd.

Thermal analysis of the wear debris of polyetheretherketone

Differential scanning calorimetry (DSC) and thermogravimetry analysis (TGA) were used to study the thermal performance of the wear debris and the worn pin tops of polyetheretherketone (PEEK) after unlubricated sliding wear tests at a constant sliding speed of 1 m s −1. It was found that the friction interfacial temperature might have ranged from 300°C to 345°C, hence favouring plastic flow mechanisms to occur and resulting in lubricating effects. In addition, thermal oxidative cross-linking reactions took place in PEEK as the wear testing proceeded, causing a reduction in the crystallizability. The most significant changes in thermal behaviour were observed from the wear debris produced under lower load ngs (i.e. 1 and 3 MPa). The possible structure-property relationships that might have affected the wear mode and the morphological feature of the wear debris are discussed.

Thermal chemistry of poly(aryl ether phthalazine)s and the synthesis of poly(aryl ether quinazoline)s

Poly(aryl ether phthalazine)s were found to undergo an exothermic reaction at a temperature range of 360–440°C. We elucidated the origin of the exothermic reaction and the physiochemical phenomena associated with it, based on thermal analyses, model compound studies, and 13C solid-state NMR studies. At elevated temperatures, polymers containing a diphenylphthalazine moiety 4 underwent extensive thermal crosslinking reactions as a result of a nitrogen elimination reaction of the phthalazine moiety. However, polymers containing the tetraphenyl or hexaphenyl phthalazine moiety 5 and 6 were found to undergo principally a backbone rearrangement reaction, in which the phthalazine moiety rearranged to a quinazoline. Utilizing this efficient thermal rearrangement of polyphenylated phthalazines, we have prepared a novel activated difluoride, 2,4-bis(4-fluorophenyl)-,5,6,7,8-tetraphenylquinazoline 9d, which underwent high-temperature solution polycondensation with BPA to give the quinazoline containing poly(aryl ether) 14. Polymer 14 is amorphous, has a glass transition temperature of 264°C, and has high thermooxidative stability with 5% weight loss being recorded at 514°C in nitrogen. © 1996 John Wiley & Sons, Inc.

Synthesis and thermal crosslinking reaction of polymers containing pendant carboxyl and epoxy groups

Synthesis and thermal crosslinking reaction of polymers containing pendant carboxyl and epoxy groups

Synthesis and thermal crosslinking reaction of polymers containing pendant carboxyl and epoxy groups

Synthesis and thermal crosslinking reaction of polymers containing pendant carboxyl and epoxy groups