Showing papers by "Edward T. Samulski published in 2015"
TL;DR: The continuous generation of monolithic polymeric parts up to tens of centimeters in size with feature resolution below 100 micrometers is demonstrated and critical control parameters are delineated and shown that complex solid parts can be drawn out of the resin at rates of hundreds of millimeters per hour.
Abstract: Additive manufacturing processes such as 3D printing use time-consuming, stepwise layer-by-layer approaches to object fabrication. We demonstrate the continuous generation of monolithic polymeric parts up to tens of centimeters in size with feature resolution below 100 micrometers. Continuous liquid interface production is achieved with an oxygen-permeable window below the ultraviolet image projection plane, which creates a "dead zone" (persistent liquid interface) where photopolymerization is inhibited between the window and the polymerizing part. We delineate critical control parameters and show that complex solid parts can be drawn out of the resin at rates of hundreds of millimeters per hour. These print speeds allow parts to be produced in minutes instead of hours.
1,787 citations
Patent•
20 Apr 2015
TL;DR: In this paper, a method of forming a 3D object is carried out by providing a carrier and a pool of immiscible liquid, the pool having a liquid build surface, the carrier and the liquid build surfaces defining a build region there between; filling the build region with a polymerizable liquid, wherein the immisible liquid is immiscibility with the polymerizable fluid, and irradiating the build regions through at least a portion of the pool to form a solid polymer from the polymersizable liquid and advancing the carrier away from the container to form the three-dimensional object
Abstract: A method of forming a three-dimensional object is carried out by: providing a carrier and a pool of immiscible liquid, the pool having a liquid build surface, the carrier and the liquid build surface defining a build region therebetween; filling the build region with a polymerizable liquid, wherein the immiscible liquid is immiscible with the polymerizable liquid (in some embodiments wherein the immiscible liquid has a density greater than the polymerizable liquid); irradiating the build region through at least a portion of the pool of immiscible liquid to form a solid polymer from the polymerizable liquid and advancing the carrier away from the liquid build surface to form the three-dimensional object comprised of the solid polymer from the polymerizable liquid. Optionally, but in some embodiments preferably, the method is carried out while also continuously maintaining a gradient of polymerization zone between the liquid build surface and the solid polymer and in contact with each thereof, the gradient of polymerization zone comprising the polymerizable liquid in partially cured form.
91 citations
Patent•
18 Jun 2015
TL;DR: In this paper, a carrier is vertically reciprocated with respect to a build surface, to enhance or speed the refilling of the build region with a solidifiable liquid, which is called CLIP.
Abstract: Described herein are methods and apparatus for the production of a three-dimensional object by "bottom up" additive manufacturing, in which a carrier (112) is vertically reciprocated with respect to a build surface, to enhance or speed the refilling of the build region with a solidifiable liquid. In preferred embodiments, the three-dimensional object is produced from a liquid interface by continuous liquid interface production (i.e., "CLIP").
40 citations
Patent•
07 Jul 2015
TL;DR: In this paper, the authors describe a method and apparatus for additive manufacturing of three-dimensional objects from polymerizable liquids, which is implemented in the form of a bottom-up additive manufacturing apparatus.
Abstract: Methods and apparatus for additive manufacturing of three-dimensional objects from polymerizable liquids are described. The methods and apparatus are implemented in the form of a bottom up additive manufacturing apparatus, and in preferred embodiments are implemented in the form of Continuous Liquid Interface Production (or “CLIP”) methods and apparatus. Rotation of at least one of the carrier and the build plate is preferably included, for example to facilitate the filling of the build region with the polymerizable liquid.
39 citations
TL;DR: In this paper, two all-aromatic, high-performance poly(etherimide)s ODPA-P3 ( I ) and BPDA-P 3 ( II ) are studied as a function of SWCNT loading.
33 citations
Patent•
12 Aug 2015
TL;DR: In this article, a carrier and an optically transparent member having a build surface, the carrier and the build surface defining a build region there between, filling the build region with a polymerizable liquid, irradiating the build regions with light through the transparent member to form a solid polymer from the polymerizable fluid, and advancing said carrier away from said build surface to form said three-dimensional object from said solid polymer.
Abstract: A method of forming a three-dimensional object includes: providing a carrier and an optically transparent member having a build surface, the carrier and the build surface defining a build region therebetween; filling the build region with a polymerizable liquid, irradiating the build region with light through the optically transparent member to form a solid polymer from the polymerizable liquid, and advancing said carrier away from said build surface to form said three-dimensional object from said solid polymer. The irradiating step includes projecting focused light at the build region, and the advancing step is carried out at a rate that is dependent on an average light intensity of the focused light.
28 citations
Patent•
12 Aug 2015
TL;DR: In this article, a carrier and an optically transparent member having a build surface, the carrier and the build surface defining a build region there between, filling the build region with a polymerizable liquid, irradiating the build regions with light through the transparent member to form a solid polymer from the polymerizable fluid, and advancing said carrier away from said build surface to form said three-dimensional object from said solid polymer.
Abstract: A method of forming a three-dimensional object includes: providing a carrier and an optically transparent member having a build surface, the carrier and the build surface defining a build region therebetween; filling the build region with a polymerizable liquid, irradiating the build region with light through the optically transparent member to form a solid polymer from the polymerizable liquid, and advancing said carrier away from said build surface to form said three-dimensional object from said solid polymer. The irradiating step includes projecting focused light at the build region, and the advancing step is carried out at a rate that is dependent on an average light intensity of the focused light.
23 citations
TL;DR: In this article, the synthesis and phase behavior of related compounds that possess lateral halogen groups and in some cases, lateral methyl groups as well were reported, showing that the low-temperature nematic phase is glassy in nature.
Abstract: We have previously demonstrated that the incorporation of lateral methyl groups on oxadiazole-based liquid crystals leads to relatively low-temperature cybotactic nematic phases which, in some cases, supercool to room temperature. We report here the synthesis and phase behaviour of related compounds that possess lateral halogen groups and in some cases, lateral methyl groups as well. Derivatives with three lateral substituents (one halogen and two methyl groups) in a specific pattern supercool in the nematic phase to room temperature. As was the case with the previously reported trimethylated derivatives, the low-temperature nematic phase is glassy in nature. Two of the new trisubstituted derivatives (with bromo and chloro groups) remain in the nematic phase upon subsequent heating until transitioning to the isotropic phase indicating that the low-temperature nematic phase may be more stable than that shown by the trimethylated analogue. Preliminary X-ray diffraction analysis confirms the presence of a ti...
18 citations
TL;DR: In this paper, the transition temperatures for several series of structural variations on bent-core mesogens derived from the asymmetric oxazole biphenol mesogenic core were reported, including trimethyl-substituted mesogens that can be supercooled to room temperature.
Abstract: We report the transition temperatures for several series of structural variations on bent-core mesogens (BCMs) derived from the asymmetric oxazole biphenol mesogenic core. Trimethyl-substituted mesogens exhibit nematic phases that can be supercooled to room temperature. Preliminary X-ray diffraction (XRD) results confirm a cybotactic supramolecular organisation in these nematics; moreover, the splitting of the diffuse wide-angle XRD feature observed in trimethylated mesogens points to an enhanced biaxial orientational correlation in the transverse molecular packing compared to other BCMs. Finally, one of the trimethyl-substituted mesogens shows the formation of a room temperature metastable fibre-like crystalline order when supercooled in a magnetic field.
16 citations
TL;DR: The deuterium NMR spectrum of benzene-d6 in a high field spectrometer (1GHz protons) exhibits a magnetic field-inducedDeuterium quadrupolar splitting Δν, and the magnitude of Δν is decreased by the pair correlations in this prototypical molecular liquid.
10 citations
TL;DR: In this article, the authors reported the first X-ray diffraction evidence of biaxial order in the fluid cybotactic nematic phase of a pair of trimethylated bent-core mesogens.
Abstract: Recently we have reported the first X-ray diffraction evidence of biaxial order in the fluid cybotactic nematic phase of a pair of trimethylated bent-core mesogens. This evidence is based on the splitting of the wide-angle diffuse scattering in the plane normal to the nematic director. The additional experimental data presented here provide further insights into this unprecedented behavior observed over the entire nematic phase. Although we could not determine the spatial extent of biaxial order—intracluster or intercluster—our observations reveal an enhanced biaxial orientational correlation in the transverse molecular packing, possibly reflecting stronger anisotropic interactions between nearest-neighbor mesogens.
TL;DR: Deuterium nuclear magnetic resonance spectra of labeled molecular liquids obtained at high fields exhibit resolved quadrupolar splittings that reflect the average orientation of the molecules relative to B, providing an experimental determination of the leading tensor component of the pair correlation function for these two molecular liquids.
Abstract: Deuterium nuclear magnetic resonance (2H NMR) spectra of labeled molecular liquids obtained at high fields, for example, |B| = 22.3 T (950 MHz proton NMR), exhibit resolved quadrupolar splittings that reflect the average orientation of the molecules relative to B. Those residual nuclear spin interactions exhibited by benzene and chloroform provide an experimental determination of the leading tensor component of the pair correlation function for these two molecular liquids. In this way, very high-field 2H NMR may be used to extract unambiguous information about liquid-state structure. Additionally, replicating the experimentally derived pair correlation function using molecular dynamics simulations provides a critical test of simulation force fields.
Patent•
06 Jan 2015
TL;DR: In this paper, a three-dimensional object of a high performance polymer (e.g., a liquid crystal thermoset polymer) is produced by using a radiation source and a carrier.
Abstract: A process for the production of a three-dimensional object of a high performance polymer (e.g., a liquid crystal thermoset polymer) is carried out by (a) providing a radiation source (e.g., a carbon dioxide laser) and a carrier for supporting a three dimensional object during production thereof, the radiation source and the carrier defining a build region; (b) providing a precursor of a high performance polymer to the build region in liquid or solid form; (c) cross-linking (e.g., thermally crosslinking) the precursor in the build region to produce a solid polymerized region of the polymer; (d) advancing said carrier with said polymerized region adhered thereto away from said build region to create a subsequent build region between the polymerized region and said radiation source; and (e) repeating steps (b) through (d) until production of the three-dimensional object is completed.
TL;DR: The detailed nature of the molecular organization within the fluid nematic phase and the temporal and spatial persistence of the organization remain unclear as discussed by the authors, however, the mounting experimental evidence points to a converging picture of the microscopic nature of this relatively new class of liquid crystals.
Abstract: The molecular clustering observed in the fluid nematic phase of nonlinear liquid crystal molecules underlies exaggerated field effects that portend unique technological advances in next-generation liquid crystal displays. However, the detailed nature of the molecular organization within the clusters and the temporal and spatial persistence of the organization remain unclear. Herein we review the evolution of structural studies of this unique nematic phase. The mounting experimental evidence points to a converging picture of the microscopic nature of this relatively new class of liquid crystals.
Patent•
10 Nov 2015
TL;DR: In this article, a method of forming a 3D object is carried out by providing a carrier and a build plate, the build plate comprising a semipermeable member, and the carrier defining a build region there between, and with the build surface in fluid communication by way of the semipermable member with a source of polymerization inhibitor.
Abstract: A method of forming a three-dimensional object, is carried out by (a) providing a carrier and a build plate, the build plate comprising a semipermeable member, the semipermeable member comprising a build surface with the build surface and the carrier defining a build region therebetween, and with the build surface in fluid communication by way of the semipermeable member with a source of polymerization inhibitor; (b) filling the build region with a polymerizable liquid, the polymerizable liquid contacting the build surface, (c) irradiating the build region through the build plate to produce a solid polymerized region in the build region, while forming or maintaining a liquid film release layer comprised of the polymerizable liquid formed between the solid polymerized region and the build surface, wherein the polymerization of which liquid film is inhibited by the polymerization inhibitor; and (d) advancing the carrier with the polymerized region adhered thereto away from the build surface on the build plate to create a subsequent build region between the polymerized region and the build surface while concurrently filling the subsequent build region with polymerizable liquid as in step (b). Apparatus for carrying out the method is also described.
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TL;DR: The authors first encountered George Gray in the stacks of the chemistry department library at Princeton, where he was a lecturer in the chemistry program and had just come from interviews with prospective Ph.D. dissertation advisers.
Abstract: I first encountered George Gray in the stacks of the chemistry department library at Princeton. That fall of 1965, I had just come from interviews with prospective Ph.D. dissertation advisers. My g...
TL;DR: In this paper, the role of optical charge generation and nongeminate recombination on the photocurrent of upright and inverted colloidal-PbS quantum-dot solar cells is investigated.
Abstract: The role of optical charge generation and nongeminate recombination on the photocurrent of upright and inverted colloidal-PbS quantum-dot solar cells is investigated. With a controlled active layer thickness, upright (PbS/fullerene) devices are found to present overall better photovoltaic performance relative to inverted devices, notwithstanding the better NIR photoconversion efficiency in the latter. Through detailed analysis and numerical optoelectronic simulations, we show that beyond incidental differences, these two device architectures have fundamentally dissimilar properties that stem from their particular optical generation characteristics and the nature of the recombination processes at play, with the inverted devices affected only by trap-assisted losses and the upright ones suffering from enhanced bimolecular recombination. This study unveils the role of device geometry and inherent material properties on the carrier generation and collection efficiency of the light-generated photocurrent in co...
Patent•
20 Apr 2015
TL;DR: In this article, a procede de formation d'un objectet tridimensionnel, effectue par : l'utilisation d'a porteur et d'une piscine de liquide non miscible, the piscinea ayant une surface d'accumulation de liquides, le dispositif porteur and la surface d', delimitant a region de construction entre eux; le remplissage de la region de reconstruction avec un liquide polymerisable, le liquide not miscible n'etant pas
Abstract: L'invention concerne un procede de formation d'un objet tridimensionnel, effectue par : l'utilisation d'un dispositif porteur et d'une piscine de liquide non miscible, la piscine ayant une surface d'accumulation de liquide, le dispositif porteur et la surface d'accumulation de liquide delimitant une region de construction entre eux ; le remplissage de la region de construction avec un liquide polymerisable, le liquide non miscible n'etant pas miscible avec le liquide polymerisable (dans certains modes de realisation, le liquide non miscible ayant une densite superieure a celle de ce liquide polymerisable) ; l'exposition de la region de construction a un rayonnement a travers au moins une partie de la piscine de liquide non miscible pour former un polymere solide a partir du liquide polymerisable et l'eloignement du dispositif porteur de la surface d'accumulation de liquide pour former l'objet tridimensionnel constitue du polymere solide forme a partir du liquide polymerisable. Eventuellement, mais de preference dans certains modes de realisation, le procede est effectue avec egalement le maintien simultane en continu d'un gradient de zone de polymerisation entre la surface d'accumulation de liquide et le polymere solide et en contact avec chacun de ces derniers, le gradient de zone de polymerisation comprenant le liquide polymerisable sous forme partiellement durcie.
Patent•
18 Jun 2015
TL;DR: In this article, an object tridimensionnel par fabrication additive "de bas en haut" is described, where un support (112) est deplace verticalement dans un mouvement de va-et-vient par rapport a surface de construction, afin dameliorer ou d'accelerer le remplissage de la zone de construction avec un liquide solidifiable.
Abstract: L'invention concerne des procedes et un appareil de production d'un objet tridimensionnel par fabrication additive "de bas en haut", selon lequel un support (112) est deplace verticalement dans un mouvement de va-et-vient par rapport a une surface de construction, afin d'ameliorer ou d'accelerer le remplissage de la zone de construction avec un liquide solidifiable. Dans des modes de realisation preferes, l'objet tridimensionnel est produit a partir d'une interface liquide par production d'interface liquide en continu (technologie CLIP).
Patent•
10 Nov 2015
TL;DR: In this paper, a method of forming a 3D object is carried out by providing a carrier and a build plate, the build plate comprising a semipermeable member, and the carrier defining a build region there between, and with the build surface in fluid communication by way of the semipermable member with a source of polymerization inhibitor.
Abstract: A method of forming a three-dimensional object, is carried out by (a) providing a carrier and a build plate, the build plate comprising a semipermeable member, the semipermeable member comprising a build surface with the build surface and the carrier defining a build region therebetween, and with the build surface in fluid communication by way of the semipermeable member with a source of polymerization inhibitor; (b) filling the build region with a polymerizable liquid, the polymerizable liquid contacting the build surface; (c) irradiating the build region through the build plate to produce a solid polymerized region in the build region, while forming or maintaining a liquid film release layer comprised of the polymerizable liquid formed between the solid polymerized region and the build surface, the polymerization of which liquid film is inhibited by the polymerization inhibitor; and (d) advancing the carrier with the polymerized region adhered thereto away from the build surface on the build plate to create a subsequent build region between the polymerized region and the build surface; (e) wherein the carrier has at least one channel formed therein, and the filling step is carried out by passing or forcing the polymerizable liquid into the build region through the at least one channel. Apparatus for carrying out the method is also described.