101
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Singamaneni S, Kharlampieva E, Jang JH, McConney ME, Jiang H, Bunning TJ, Thomas EL, Tsukruk VV. Metalized porous interference lithographic microstructures via biofunctionalization. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2010; 22:1369-1373. [PMID: 20437484 DOI: 10.1002/adma.200902893] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
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102
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Gomopoulos N, Maschke D, Koh CY, Thomas EL, Tremel W, Butt HJ, Fytas G. One-dimensional hypersonic phononic crystals. NANO LETTERS 2010; 10:980-4. [PMID: 20141118 DOI: 10.1021/nl903959r] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
We report experimental observation of a normal incidence phononic band gap in one-dimensional periodic (SiO(2)/poly(methyl methacrylate)) multilayer film at gigahertz frequencies using Brillouin spectroscopy. The band gap to midgap ratio of 0.30 occurs for elastic wave propagation along the periodicity direction, whereas for inplane propagation the system displays an effective medium behavior. The phononic properties are well captured by numerical simulations. The porosity in the silica layers presents a structural scaffold for the introduction of secondary active media for potential coupling between phonons and other excitations, such as photons and electrons.
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103
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Ma M, Thomas EL, Rutledge GC, Yu B, Li B, Jin Q, Ding D, Shi AC. Gyroid-Forming Diblock Copolymers Confined in Cylindrical Geometry: A Case of Extreme Makeover for Domain Morphology. Macromolecules 2010. [DOI: 10.1021/ma9022586] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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104
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Ho RM, Chiang YW, Chen CK, Wang HW, Hasegawa H, Akasaka S, Thomas EL, Burger C, Hsiao BS. Block Copolymers with a Twist. J Am Chem Soc 2009; 131:18533-42. [DOI: 10.1021/ja9083804] [Citation(s) in RCA: 111] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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105
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Hsiao MS, Zheng JX, Van Horn RM, Quirk RP, Thomas EL, Chen HL, Lotz B, Cheng SZD. Poly(ethylene oxide) Crystal Orientation Change under 1D Nanoscale Confinement using Polystyrene-block-poly(ethylene oxide) Copolymers: Confined Dimension and Reduced Tethering Density Effects. Macromolecules 2009. [DOI: 10.1021/ma901565h] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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106
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Politakos N, Ntoukas E, Avgeropoulos A, Krikorian V, Pate BD, Thomas EL, Hill RM. Strongly segregated cubic microdomain morphology consistent with the double gyroid phase in high molecular weight diblock copolymers of polystyrene and poly(dimethylsiloxane). ACTA ACUST UNITED AC 2009. [DOI: 10.1002/polb.21838] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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107
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Kang C, Kim E, Baek H, Hwang K, Kwak D, Kang Y, Thomas EL. Full Color Stop Bands in Hybrid Organic/Inorganic Block Copolymer Photonic Gels by Swelling−Freezing. J Am Chem Soc 2009; 131:7538-9. [DOI: 10.1021/ja9021478] [Citation(s) in RCA: 103] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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108
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Jang JH, Koh CY, Bertoldi K, Boyce MC, Thomas EL. Combining pattern instability and shape-memory hysteresis for phononic switching. NANO LETTERS 2009; 9:2113-2119. [PMID: 19391612 DOI: 10.1021/nl9006112] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
We report a fully reversible and robust shape-memory effect in a two-dimensional nanoscale periodic structure composed of three steps, the elastic instability governing the transformation, the plasticity that locks in the transformed pattern as a result of an increase in glass transition temperature (T(g)), and the subsequent elastic recovery due to the vapor-induced decrease in T(g). Solvent swelling of a cross-linked epoxy/air cylinder structure induces an elastic instability that causes a reversible change in the shape of the void regions from circular to oval. The pattern symmetry changes from symmorphic p6mm to nonsymmorphic p2gg brought via the introduction of new glide symmetry elements and leads to a significant change in the phononic band structure, specifically in the opening of a new narrow-band gap due to anticrossing of bands, quite distinct from gaps originating from typical Bragg scattering. We also demonstrate that numerical simulations correctly capture the three steps of the shape-memory cycle observed experimentally.
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109
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Ma M, Titievsky K, Thomas EL, Rutledge GC. Continuous concentric lamellar block copolymer nanofibers with long range order. NANO LETTERS 2009; 9:1678-1683. [PMID: 19351195 DOI: 10.1021/nl900265y] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Fibers with long-range ordered internal structures have applications in various areas such as photonic band gap fibers, optical waveguides, wearable power, sensors, and sustained drug release. Up to now, such fibers have been formed by melt extrusion or drawing from a macroscopic preformed rod and were typically limited to diameters >10 microm with internal features >1 microm (Abouraddy, A. F.; et al. Nat. Mater. 2007, 6, 336). We describe a new class of continuous fibers and fibrous membranes with long-range ordered concentric lamellar structure that have fiber diameters and feature sizes 2-3 orders of magnitude smaller than those made by conventional methods. These fibers are created through confined self-assembly of block copolymers within core-shell electrospun filaments. In contrast to the copolymer in bulk or thin films, the domains of the concentric lamellar structure are shown here to vary quantitatively with (radial) position and to exhibit a novel dislocation that accommodates variations in fiber diameter robustly, permitting for the first time the realization of long-range order in technologically meaningful, continuous fibers with approximately 300 nm diameter and 50 nm radial period.
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110
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Waletzko RS, Korley LTJ, Pate BD, Thomas EL, Hammond PT. Role of Increased Crystallinity in Deformation-Induced Structure of Segmented Thermoplastic Polyurethane Elastomers with PEO and PEO−PPO−PEO Soft Segments and HDI Hard Segments. Macromolecules 2009. [DOI: 10.1021/ma8022052] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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111
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Jeong KU, Jang JH, Koh CY, Graham MJ, Jin KY, Park SJ, Nah C, Lee MH, Cheng SZD, Thomas EL. Colour-tunable spiral photonic actuators. ACTA ACUST UNITED AC 2009. [DOI: 10.1039/b822980p] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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112
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Singamaneni S, Bertoldi K, Chang S, Jang JH, Thomas EL, Boyce MC, Tsukruk VV. Instabilities and pattern transformation in periodic, porous elastoplastic solid coatings. ACS APPLIED MATERIALS & INTERFACES 2009; 1:42-47. [PMID: 20355751 DOI: 10.1021/am800078f] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Pattern transformation in periodic microporous elastoplastic solid coatings is caused by a buckling of the struts and a rotation of the nodes under compressive stresses. The results of a nonlinear numerical investigation confirm the critical role of the bifurcation of the periodic solid under compressive stresses. In striking contrast to the earlier observations of elastic instabilities in porous elastomeric solids, the elastic-plastic nature of the cross-linked periodic microstructure studied here provides the ability to lock in the transformed pattern with complete relaxation of the internal stresses. The study unveils a novel deformation mode in porous periodic solids in the form of organized buckling instability of weak strut elements.
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113
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Alcazar D, Wang F, Swager TM, Thomas EL. Gel Processing for Highly Oriented Conjugated Polymer Films. Macromolecules 2008. [DOI: 10.1021/ma8020739] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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114
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Hsiao MS, Zheng JX, Leng S, Van Horn RM, Quirk RP, Thomas EL, Chen HL, Hsiao BS, Rong L, Lotz B, Cheng SZD. Crystal Orientation Change and Its Origin in One-Dimensional Nanoconfinement Constructed by Polystyrene-block-poly(ethylene oxide) Single Crystal Mats. Macromolecules 2008. [DOI: 10.1021/ma801641w] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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115
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Tsui NT, Yang Y, Mulliken AD, Torun L, Boyce MC, Swager TM, Thomas EL. Enhancement to the rate-dependent mechanical behavior of polycarbonate by incorporation of triptycenes. POLYMER 2008. [DOI: 10.1016/j.polymer.2008.08.038] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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116
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Thomas EL, Uthaya S, Vasu V, McCarthy JP, McEwan P, Hamilton G, Bell JD, Modi N. Neonatal intrahepatocellular lipid. Arch Dis Child 2008; 93:F382-3. [PMID: 18723779 DOI: 10.1136/adc.2007.127431] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
There is increasing evidence that preterm birth is a risk factor for the development of adiposity associated disease, although the pathophysiological basis is unclear. We have previously shown that preterm infants have increased internal abdominal (visceral) adiposity by term. In adults increased internal adiposity is associated with elevated intrahepatocellular lipid (IHCL). We measured IHCL using (1)H NMR spectroscopy in 26 infants (eight healthy preterm-at-term and 18 term-born) and compared values with a reference group of 32 adults. There was no significant difference between adult and term-born IHCL content. In preterm-at-term infants IHCL was significantly elevated when compared with term-born infants and with adults (IHCL CH2/water median (interquartile range): preterm 1.69 (1.04-3.53), term 0.21 (0-0.54) and adult 0.55 (0.08-1.57).
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117
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Bita I, Yang JKW, Jung YS, Ross CA, Thomas EL, Berggren KK. Graphoepitaxy of self-assembled block copolymers on two-dimensional periodic patterned templates. Science 2008; 321:939-43. [PMID: 18703736 DOI: 10.1126/science.1159352] [Citation(s) in RCA: 504] [Impact Index Per Article: 31.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Self-assembling materials are the building blocks of bottom-up nanofabrication processes, but they need to be templated to impose long-range order and eliminate defects. In this work, the self-assembly of a thin film of a spherical-morphology block copolymer is templated using an array of nanoscale topographical elements that act as surrogates for the minority domains of the block copolymer. The orientation and periodicity of the resulting array of spherical microdomains are governed by the commensurability between the block copolymer period and the template period and is accurately described by a free-energy model. This method, which forms high-spatial-frequency arrays using a lower-spatial-frequency template, will be useful in nanolithography applications such as the formation of high-density microelectronic structures.
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118
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Mickiewicz RA, Ntoukas E, Avgeropoulos A, Thomas EL. Phase Behavior of Binary Blends of High Molecular Weight Diblock Copolymers with a Low Molecular Weight Triblock. Macromolecules 2008. [DOI: 10.1021/ma801022k] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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119
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120
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Hsiao MS, Chen WY, Zheng JX, Van Horn RM, Quirk RP, Ivanov DA, Thomas EL, Lotz B, Cheng SZD. Poly(ethylene oxide) Crystallization within a One-Dimensional Defect-Free Confinement on the Nanoscale. Macromolecules 2008. [DOI: 10.1021/ma8006619] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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121
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Cheng W, Gomopoulos N, Fytas G, Gorishnyy T, Walish J, Thomas EL, Hiltner A, Baer E. Phonon dispersion and nanomechanical properties of periodic 1D multilayer polymer films. NANO LETTERS 2008; 8:1423-1428. [PMID: 18363344 DOI: 10.1021/nl080310w] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
We report on the first systematic study of phonon propagation in nanostructured composite polymer multilayer films as a function of periodicity and composition using Brillouin light scattering and numerical simulations. The high sensitivity of phonon dispersion to structure and composition allows the probing of the mechanical properties down to the single-layer level. We observe a strikingly different dependence of the longitudinal and shear moduli on confinement effects in the polymer nanolayers. In addition, temperature dependent measurements of sound velocities reveal the presence of distinct glass transition temperatures, indicative of phonon localization in films with large layer thicknesses in agreement with theoretical predictions.
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122
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Jang JH, Jhaveri SJ, Rasin B, Koh C, Ober CK, Thomas EL. Three-dimensionally-patterned submicrometer-scale hydrogel/air networks that offer a new platform for biomedical applications. NANO LETTERS 2008; 8:1456-1460. [PMID: 18393470 DOI: 10.1021/nl080444+] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Phase mask interference lithography was employed to fabricate three-dimensional (3D) hydrogel structures with high surface area on neural prosthetic devices. A random terpolymer of poly(hydroxyethyl methacrylate- ran-methyl methacrylate- ran-methacrylic acid) was synthesized and used as a negative-tone photoresist to generate bicontinuous 3D hydrogel structures at the submicrometer scale. We demonstrated that the fully open 3D hydrogel/air networks can be used as a pH-responsive polymeric drug-release system for the delivery of neurotrophins to enhance the performance of neural prosthetic devices. Additionally an open hydrogel structure will provide direct access of neuronal growth to the device for improved electrical coupling.
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123
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Park JW, Cho J, Thomas EL. Alignment and anchoring transition of liquid crystals on the surface of self-assembled block copolymer films with periodic defects. SOFT MATTER 2008; 4:739-743. [PMID: 32907177 DOI: 10.1039/b718482d] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Patterned alignment of the nematic and uniform homeotropic alignment of the smectic LC occur on the periodic bend-splay Neél wall defect pattern of a rod-coil copolymer substrate surface.
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124
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Singamaneni S, Chang S, Jang JH, Davis W, Thomas EL, Tsukruk VV. Mechanical properties of composite polymer microstructures fabricated by interference lithography. Phys Chem Chem Phys 2008; 10:4093-105. [DOI: 10.1039/b719709h] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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125
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Takamatsu Y, Dunmeyer D, Thomas EL, Warde C. Preparation, characterization, and heat resistance studies of a holographic photopolymer based on SU-8 epoxy resin. OPTICS LETTERS 2008; 33:7-9. [PMID: 18157240 DOI: 10.1364/ol.33.000007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
A holographic photopolymer based on SU-8 epoxy resin as the binder and trimethylolpropane ethoxylate triacrylate as the monomer with an iodonium salt photoinitiator was studied. A diffraction efficiency of 93% and a refractive index modulation (Delta n) of 1.3 x 10(-2) were obtained from a 16 microm thick sample with write beam intensities of 50 mW/cm(2) at a wavelength of 514.5 nm, an exposure time of 60 s, and a postbaking at 65 degrees C for 1 h. The material exhibits good heat resistance in the range from 40 degrees C to 160 degrees C and long projected life.
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