“…The FTIR spectra of the chelated precursors are similar and show a large number of absorption bands/peaks between 750 and 1800 cm −1 ( Table 2 ). The pair of absorption peaks close to 1609 cm −1 and 1522 cm −1 is attributed to the bidentate character of cation‐bonded MAEAA and hence is indicative of the formation of the chelated complex 24, 25. These peaks correspond to the ν(CO) and v(CC) vibrations of the chelate ring, respectively.…”
Section: Resultsmentioning
confidence: 98%
“…The enol form of MAEAA is stabilized by chelation with an alkoxide. Further, the reaction also results in the stoichiometric replacement of an alkoxy group (e.g., an iso ‐propoxy group from gallium (III) iso ‐propoxide) by a β‐ketoester ligand,23–25 as shown in Equation 2. The general reaction of an alkoxide with MAEAA is shown in Equation 3.…”
Direct patterning of oxides using thermal nanoimprint lithography is performed using either the sol-gel or methacrylate route. The sol-gel method results in resists with long shelf-life, but with high surface energy and a considerable amount of solvent that affects the quality of imprinting. The methacrylate route, which is limited to certain oxides, produces polymerizable resists, leading to low surface energy, but suffers from the shorter shelf-life of precursors. By combining the benignant elements from both these routes, a universal method of direct thermal nanoimprinting of oxides is demonstrated using precursors produced by reacting an alkoxide with a polymerizable chelating agent such as 2-(methacryloyloxy)ethyl acetoacetate (MAEAA). MAEAA possesses β -ketoester, which results in the formation of environmentally stable, chelated alkoxide with long shelf-life, and methacrylate groups, which provide a reactive monomer pendant for in situ copolymerization with a cross-linker during imprinting. Polymerization leads to trapping of cations, lowering of surface energy, strengthening of imprints, which enables easy and clean demolding over 1 cm × 2 cm patterned area with ≈ 100% yield. Heat-treatment of imprints gives amorphous/crystalline oxide patterns. This alliance between two routes enables the successful imprinting of numerous oxides including
“…The FTIR spectra of the chelated precursors are similar and show a large number of absorption bands/peaks between 750 and 1800 cm −1 ( Table 2 ). The pair of absorption peaks close to 1609 cm −1 and 1522 cm −1 is attributed to the bidentate character of cation‐bonded MAEAA and hence is indicative of the formation of the chelated complex 24, 25. These peaks correspond to the ν(CO) and v(CC) vibrations of the chelate ring, respectively.…”
Section: Resultsmentioning
confidence: 98%
“…The enol form of MAEAA is stabilized by chelation with an alkoxide. Further, the reaction also results in the stoichiometric replacement of an alkoxy group (e.g., an iso ‐propoxy group from gallium (III) iso ‐propoxide) by a β‐ketoester ligand,23–25 as shown in Equation 2. The general reaction of an alkoxide with MAEAA is shown in Equation 3.…”
Direct patterning of oxides using thermal nanoimprint lithography is performed using either the sol-gel or methacrylate route. The sol-gel method results in resists with long shelf-life, but with high surface energy and a considerable amount of solvent that affects the quality of imprinting. The methacrylate route, which is limited to certain oxides, produces polymerizable resists, leading to low surface energy, but suffers from the shorter shelf-life of precursors. By combining the benignant elements from both these routes, a universal method of direct thermal nanoimprinting of oxides is demonstrated using precursors produced by reacting an alkoxide with a polymerizable chelating agent such as 2-(methacryloyloxy)ethyl acetoacetate (MAEAA). MAEAA possesses β -ketoester, which results in the formation of environmentally stable, chelated alkoxide with long shelf-life, and methacrylate groups, which provide a reactive monomer pendant for in situ copolymerization with a cross-linker during imprinting. Polymerization leads to trapping of cations, lowering of surface energy, strengthening of imprints, which enables easy and clean demolding over 1 cm × 2 cm patterned area with ≈ 100% yield. Heat-treatment of imprints gives amorphous/crystalline oxide patterns. This alliance between two routes enables the successful imprinting of numerous oxides including
“…This is indicative of the formation of the chelated complex. 35,36 Noteworthy is the presence of characteristic peaks of the carbonyl group at 1721 cm −1 and the methacrylate double bond at 1634 cm −1 in MAEAA-functionalized metal oxide precursors; the latter strongly suggests the preservation of a polymerizable double bond in the complex. A shoulder at 1746 cm -1 that corresponds to the carbonyl group of MAEAA may indicate incomplete reaction between MAEAA and the corresponding metal alkoxides (Figure 1b).…”
Step-and-flash imprint lithography (S-FIL) is a wafer-scale, high-resolution nanoimprint technique capable of expansion of nanoscale patterns via serial patterning of imprint fields. While S-FIL patterning of organic resins is well known, patterning of metal-organic resins followed by calcination to form structured oxide films remains relatively unexplored. However, with calcination shrinkage, there is tremendous potential utility in easing accessibility of arbitrary nanostructures at 20 nm resolution and below. However, barriers to commercial adoption exist due to difficulties in formulating polymerizable oxide precursors with good dispensability, long shelf life, and resistance to auto-homopolymerization. Here we propose a solution to these issues in the form of a versatile resin formulation scheme that is applicable to a host of functional oxides (Al2O3, HfO2, TiO2, ZrO2, Ta2O5, and Nb2O5). This scheme utilizes a reaction of metal alkoxides with 2-(methacryloyloxy)ethyl acetoacetate (MAEAA), a polymerizable chelating agent. Formation of these inorganic coordination complexes enables remarkable resistance to auto-homopolymerization, greatly improving dispensability and shelf life, thus enabling full scale-up of this facile nanofabrication approach. Results include successively imprinted fields consisting of 100 nm linewidth gratings. Isothermal calcination of these structures resulted in corresponding shrinkage of 75-80% without loss of mechanical integrity or aspect ratio, resulting in 20 nm linewidth oxide nanostructures.
“…Compounds used as such controlling agents are carboxylic acids, , diols, β-diketones, and isoeugenole-type compounds . β-Keto esters with attached polymerizable bonds such as 2-(methacryloyloxy)ethyl acetoacetate (HAAEMA) have only been rarely employed in the modification of metal alkoxides. ,− In all literature-described cases free radical polymerization was used to form the polymer matrix . This technique has the advantage of being applicable to a large number of monomers under a variety of reaction conditions (temperature, solvents).…”
Well-defined complexes of Ti and Zr alkoxides and β-keto ester ligands carrying polymerizable
double bonds were copolymerized with methyl methacrylate applying atom transfer radical polymerization. The
structure and the morphology of the obtained hybrid polymers were investigated using NMR, FT-IR, and size
exclusion chromatography. All methods revealed an incorporation of both comonomers in the polymer backbone.
NMR and FT-IR analyses demonstrated that after polymerization the chemical linkage between the metal alkoxides
and the organic macromolecules was preserved. The alkoxide-containing macromolecules were used as precursors
in the formation of metal oxide-containing nanocomposites applying the sol−gel process. The decomposition
temperature of the final nanocomposites increased depending on the chemical composition of the materials. Small-angle X-ray scattering investigations revealed a short-range order for the polymers containing Ti-alkoxides which
disappeared after carrying out the sol−gel process due to the hydrolysis of the well-defined complexes. Transmission
electron microscopy showed the formation of amorphous metal oxide nanoparticles inside the polymer network
with diameters of a few nanometers. The particles were highly dispersed due to the low mobility of the alkoxides
in the matrix during the sol−gel process.
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