Polybenzoxazine as a mold-release agent for nanoimprint lithography

Synthesis of Multilayered DLC Films with Wear Resistance and Antiseizure Properties

Diamond-like carbon (DLC) films have attracted considerable interest for application as protective films in diverse industrial parts. This is attributed to their desirable characteristics, such as high hardness, low coefficient of friction, gas-barrier properties, and corrosion resistance. Antiseizure properties, in addition to wear resistance, are required during the die molding of polymer and polymer-matrix composite parts. Graphite films can be easily peeled because the vertically stacked graphene sheets are bonded via weak van der Waals forces. The present study demonstrates the fabrication of multilayered DLC/Cu films, where the Cu film functions as a catalyst for the formation of a graphite-like layer between the DLC and Cu films. The DLC/Cu film was synthesized on a Si (100) substrate via plasma-enhanced chemical vapor deposition and magnetron sputtering. The peelability, wear resistance, microstructure, texture, and cross-section of the film were experimentally analyzed. The results indicated a variation in the peelability with the deposition conditions of the Cu film that comprised particles with diameters of several nanometers. The DLC film at the interface in contact with the Cu film was transformed into a graphite-like state i.e., graphitized. The surface of the multilayered film exhibited antiseizure properties with the peeling of the upper DLC film. The multilayered film also exhibited wear resistance owing to the repeated appearances of a new DLC film. It is expected that the wear-resistant films with antiseizure properties demonstrated in the present study will be utilized in various industrial sectors.

Characteristics of Thermosetting Polymer Nanocomposites: Siloxane-Imide-Containing Benzoxazine with Silsesquioxane Epoxy Resins

A series of innovative thermosetting polymer nanocomposites comprising of polysiloxane-imide-containing benzoxazine (PSiBZ) as the matrix and double-decker silsesquioxane (DDSQ) epoxy or polyhedral oligomeric silsesquioxane (POSS) epoxy were prepared for improving thermosetting performance. Thermomechanical and dynamic mechanical characterizations indicated that both DDSQ and POSS could effectively lower the coefficient of thermal expansion by up to approximately 34% and considerably increase the storage modulus (up to 183%). Therefore, DDSQ and POSS are promising materials for low-stress encapsulation for electronic packaging applications.

Direct synthesis of poly(benzoxazine imide) from an ortho-benzoxazine: its thermal conversion to highly cross-linked polybenzoxazole and blending with poly(4-vinylphenol)

A facile one-pot synthesis of a poly(benzoxazine imide), NDOPoda Bz, was prepared without the need for either the preparation of an amino-functionalized benzoxazine or subsequent thermal treatment.

The role of hydrophobic silane coating on Si stamps in nanoimprint lithography

Hydrophobic silane coatings have been successfully applied to the surface of Si stamps to improve demolding in nanoimprint lithography (NIL). However, the role of the silane coating has only been studied either indirectly, by measuring adhesion or friction coefficients for Si and substrate surfaces without patterns, or collectively, by measuring the overall demolding force that does not differentiate contributions of friction dissipation, stored elastic energy, and adhesion. Here, for the first time, we present experimental evidence on the role of the silane coating in improving demolding in UV-NIL by using different silane coatings. The silane coatings were characterized by x-ray photoelectron spectroscopy, water contact angle, and friction force measurements. Then, the work of demolding was systematically measured for different silane coatings using stamps with the same micropattern but different pattern depths. Comparison of the results to the theoretical model developed for fiber-matrix debonding energy by Sutcu and Hillig [Acta Metall. Mater. 38(12), 2653-2662] indicated that with a hydrophobic silane coating, the main parameter contributing to overall demolding work shifts from adhesion to stored elastic energy and frictional dissipation as surface adhesion keeps decreasing. The results confirm that the main role of the silane coating in reducing the demolding is to reduce surface adhesion rather than friction at the stamp/substrate interface.

Phosphorus-containing polymers from THPS. IV: Synthesis and properties of phosphorus-containing polybenzoxazines as a green route for recycling toxic phosphine (PH3) tail gas

A convenient route to convert the highly toxic phosphine (PH₃) tail gas into high-performance polybenzoxazines was first described in this paper. Two aliphatic polyamines, namely tris(aminomethyl)phosphine oxide and bis(aminomethyl)phenylphosphine oxide, were synthesized from tetrakis(hydroxymethyl)phosphonium sulfate (THPS), a green derivative of PH₃ tail gas. And then two novel phosphorus-containing benzoxazine monomers, tris(3,4-dihydro-2H-1,3-benzoxazin-3-yl-methyl)phosphine oxide (TBOz) and benzylbis(3,4-dihydro-2H-1,3-benzoxazin-3-yl-methyl) phosphine oxide (BBOz) were prepared by three-steps procedure. FT-IR and DSC technologies were adopted to study the thermal-initiated polymerization behaviors of two benzoxazine monomers. Thermal properties of these crosslinked polymers were studied by TGA and DMA. The results display that the polybenzoxazines (PTBOz and PBBOz) exhibite good thermal stabilities and high glass transition temperatures. The char yield of polybanzoxazine is high as 47% and indiactes that phosphorus-containing polybenzoxazines show high fire-retardancy. The surface free energies of the PTBOz and PBBOz are 37.1 and 40.4mJm^-2 by Owens two-liquid method. The dielectric properties of the PTBOz and PBBOz remaine near constant in the experimental frequency range.

Polybenzoxazine/Polyhedral Oligomeric Silsesquioxane (POSS) Nanocomposites

The organic/inorganic hybrid materials from polyhedral oligomeric silsesquioxane (POSS, inorganic nanoparticles) and polybenzoxazine (PBZ) have received much interesting recently due to their excellent thermal and mechanical properties, flame retardance, low dielectric constant, well-defined inorganic framework at nanosized scale level, and higher performance relative to those of non-hybrid PBZs. This review describes the synthesis, dielectric constants, and thermal, rheological, and mechanical properties of covalently bonded mono- and multifunctionalized benzoxazine POSS hybrids, other functionalized benzoxazine POSS derivatives, and non-covalently (hydrogen) bonded benzoxazine POSS composites.

Ternary polybenzoxazine/POSS/SWCNT hybrid nanocomposites stabilized through supramolecular interactions

In this study we linked zero-dimensional polyhedral oligomeric silsesquioxane (POSS) with one-dimensional single-walled carbon nanotubes (SWCNTs) as dual-dimensional nanohybrid complexes within polybenzoxazine matrices, stabilized through noncovalent supramolecular interactions. First, we synthesized a new bifunctionalized benzoxazine (Py-Bz-T), presenting thymine (T) and pyrene (Py) units, that displayed excellent thermal properties after thermal curing, because its T moieties increased the physical cross-linking density. Second, we prepared Py-Bz-T/OBA-POSS [octuply adenine (A)-functionalized POSS] nanocomposites and investigated, using nuclear magnetic resonance and Fourier transform infrared spectroscopies, the multiple hydrogen bonding AT interactions between Py-Bz-T and OBA-POSS. Finally, we prepared Py-Bz-T/OBA-POSS/SWCNT ternary hybrid complexes dispersed in THF, stabilized through both multiple hydrogen bonding and π-π stacking interactions. Transmission electron microscopy revealed that the SWCNTs were highly dispersed and covered by the Py-Bz-T/OBA-POSS nanocomposites; these ternary hybrid complexes were stabilized through π-π interactions between Py-Bz-T/OBA-POSS and the SWCNTs, as evidenced using fluorescence spectroscopy.

Multivalent photo-crosslinkable coumarin-containing polybenzoxazines exhibiting enhanced thermal and hydrophobic surface properties

Mono-, bi-, and trivalent coumarin-containing benzoxazine monomers were synthesized by facile Mannich reactions of 4-methyl-7-hydroxycoumarin and paraformaldehyde with aniline, bisphenol A–NH₂, and 1,3,5-tri(4-aminobenzene).

Thermal property of an aggregation-induced emission fluorophore that forms metal–ligand complexes with Zn(ClO4)2 of salicylaldehyde azine-functionalized polybenzoxazine

A salicylaldehyde azine-functionalized benzoxazine monomer formed zinc ion complexes not only improved the thermal properties but also facilitated ring-opening polymerization.

Bifunctional polybenzoxazine nanocomposites containing photo-crosslinkable coumarin units and pyrene units capable of dispersing single-walled carbon nanotubes

A new bifunctional benzoxazine monomer possessing both coumarin and pyrene groups for photo-crosslinking and dispersing single-walled carbon nanotubes.

A cross-linkable triphenylamine derivative as a hole injection/transporting material in organic light-emitting diodes

A new thermally cross-linkable triphenylamine derivative containing a benzoxazine functional group for application in organic light-emitting diodes (OLEDs.)

Multifunctional polybenzoxazine nanocomposites containing photoresponsive azobenzene units, catalytic carboxylic acid groups, and pyrene units capable of dispersing carbon nanotubes

A new multifunctional benzoxazine monomer Azo-COOH-Py BZ includes an azobenzene unit, a carboxylic acid group, and a pyrene moiety.

Design of hydrophobic polydimethylsiloxane and polybenzoxazine hybrids for interlayer low k dielectrics

Graphical representation of layer-by-layer arrangement of polydimethylsiloxane based polybenzoxazine hybrids.

Brønsted acid-promoted [3 + 3] cycloaddition of azomethine ylides with quinone monoimine: a practical method towards dihydrobenzoxazine derivatives

Brønsted acid-promoted [3 + 3] cycloaddition of azomethine ylides with quinone monoimine provided an expedient access to dihydrobenzoxazine derivatives.

Azopyridine-functionalized benzoxazine with Zn(ClO4)2form high-performance polybenzoxazine stabilized through metal–ligand coordination

Azopyridine-functionalized benzoxazine (PBZ) was prepared and then blended with zinc ion through metal–ligand coordination to form a high performance polybenzoxazine after thermal curing.

Controlling mold releasing propensity--the role of surface energy and a multiple chain transfer agent

As the desired feature size of mold-assisted lithography decreases rapidly efficient demolding process becomes more challenging due to strong adhesion between polymeric resists and fine-featured molds. We synthesized new macromolecular additives and investigated the effects of surface energy and contraction of resist materials on demolding propensity by monitoring the adhesion force between the resist and the applied mold. The resist's surface energy was controlled, as inferred from water contact angle measurements, by chemically modifying its hydroxyl functionality. The resist's degree of volume shrinkage during the photocuring procedure was also controlled by mixing in a newly developed chemical that has a multiple radical chain transfer capability. The adhesion force was proportionally reduced as the surface energy of the resist materials decreased and as the volume shrinkage was reduced. When the volume shrinkage control was applied in conjunction with the low surface energy resist material (LS-30UV), we obtained an optimized condition requiring a minimum force for releasing the mold from the cured resist layer.

Effect of surface tension and coefficient of thermal expansion in 30 nm scale nanoimprinting with two flexible polymer molds

We report on nanoimprinting of polymer thin films at 30 nm scale resolution using two types of ultraviolet (UV)-curable, flexible polymer molds: perfluoropolyether (PFPE) and polyurethane acrylate (PUA). It was found that the quality of nanopatterning at the 30 nm scale is largely determined by the combined effects of surface tension and the coefficient of thermal expansion of the polymer mold. In particular, the polar component of surface tension may play a critical role in clean release of the mold, as evidenced by much reduced delamination or broken structures for the less polarized PFPE mold when patterning a relatively hydrophilic PMMA film. In contrast, such problems were not notably observed with a relatively hydrophobic PS film for both polymer molds. In addition, the demolding characteristic was also influenced by the coefficient of thermal expansion so that no delamination or uniformity problems were observed when patterning a UV-curable polymer film at room temperature. These results suggest that a proper polymeric mold material needs to be chosen for patterning polymer films under different surface properties and processing conditions, providing insights into how a clean demolding characteristic can be obtained at 30 nm scale nanopatterning.

Preparation and surface properties of novel low surface free energy fluorinated silane-functional polybenzoxazine films

A novel fluorinated silane-functional benzoxazine monomer is synthesized, and the structure is characterized by FTIR and (1)H NMR. Chemical bonds Si-O-Si linkage between the benzoxazine monomer and the substrate are identified through the variation of water contact angles. The low surface free energy calculation and mechanism of the benzoxazine polymer films are proved through contact angle measurement and FTIR. The film formation property and thermal stability of the polybenzoxazine are also investigated. These results clearly show that this novel polybenzoxazine can not only bond to the substrate but also possess even lower surface free energy which is 15.5 mJ/m(2). The polymer also possesses well thermal stability with a glass transition temperature of 188 °C and the 5% weight loss temperatures of 276 °C.