Visible‐light‐driven Rapid 3d Printing of Photoresponsive Resins for Optically Clear Multifunctional 3d Objects
Light-driven three-dimensional (3D) printing is gaining significant attention for its unparalleled build speed and high-resolution in additive manufacturing. However, extending vat photopolymerization to multifunctional, photoresponsive materials poses challenges, such as light attenuation and interference between the photocatalysts and photoactive moieties. This study introduces novel visible-light-driven acrylic resins that enable rapid, high-resolution photoactive 3D printing. The synergistic combination of a cyanine-based photocatalyst, borate, and iodonium coinitiators achieves an excellent printing rate and feature resolution under low-intensity, red light exposure. The incorporation of novel hexaarylbiimidazole (HABI) crosslinkers allows for spatially-resolved photoactivation upon exposure to violet/blue light. Furthermore, a photobleaching mechanism inhibited by HNu 254 during the photopolymerization process results in the production of optically-clear 3D printed objects. Real-time Fourier transform infrared spectroscopy validates the rapid photopolymerization of the HABI-containing acrylic resin, whereas mechanistic evaluations reveal the underlying dynamics that are responsible for the rapid photopolymerization rate, wavelength-orthogonal photoactivation, and observed photobleaching phenomenon. Ultimately, this visible-light-based printing method demonstrates: (i) rapid printing rate of 22.5 mm/h, (ii) excellent feature resolution (approximately 20 µm), and (iii) production of optically clear object with self-healing capability and spatially controlled cleavage. This study serves as a roadmap for developing next-generation “smart” 3D printing technologies.
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Thu 01 Feb 15:00: 2D Helium Atom Diffraction from a Microscopic Spot
A method for measuring helium atom diffraction with micron-scale spatial resolution is demonstrated in a scanning helium microscope (SHeM) and applied to study a micron-scale spot on the (100) plane of a lithium fluoride (LiF) crystal. The positions of the observed diffraction peaks provide an accurate measurement of the local lattice spacing, while a combination of close-coupled scattering calculations and Monte Carlo ray-tracing simulations reproduce the main variations in diffracted intensity. Subsequently, the diffraction results are used to enhance image contrast by measuring at different points in reciprocal space. The results open up the possibility for using helium microdiffraction to characterize the morphology of delicate or electron-sensitive materials on small scales. These include many fundamentally and technologically important samples which cannot be studied in conventional atom scattering instruments, such as small grain size exfoliated 2D materials, polycrystalline samples, and other surfaces that do not exhibit long-range order.
- Speaker: Nick von Jeinsen, Surface and 2D Nanoscience, Cavendish Laboratory
- Thursday 01 February 2024, 15:00-16:00
- Venue: Mott Seminar Room, Cavendish Laboratory.
- Series: Physics and Chemistry of Solids Group; organiser: Stephen Walley.
Tue 23 Apr 14:00: Title to be confirmed
Abstract not available
- Speaker: Joseph Bonneau, New York University
- Tuesday 23 April 2024, 14:00-15:00
- Venue: Webinar & LT2, Computer Laboratory, William Gates Building..
- Series: Computer Laboratory Security Seminar; organiser: Hridoy Sankar Dutta.
Tunable Adhesion for All‐Dry Transfer of Two‐Dimensional Materials Enabled by The Freezing of Transfer Medium
The real applications of CVD-grown graphene films require the reliable techniques for transferring graphene from growth substrates onto application-specific substrates. The transfer approaches that avoid the use of organic solvents, etchants and strong bases are compatible with industrial batch processing, in which graphene transfer should be conducted by dry exfoliation and lamination. However, all-dry transfer of graphene remains unachievable owing to the difficulty in precisely controlling interfacial adhesion to enable the crack- and contamination-free transfer. Herein, through controllable crosslinking of transfer medium polymer, we successfully tuned the adhesion between the polymer and graphene for all-dry transfer of graphene wafers. Stronger adhesion enables crack-free peeling of the graphene from growth substrates, while reduced adhesion facilitates the exfoliation of polymer from graphene surface leaving an ultraclean surface. This work provides an industrially compatible approach for transferring two-dimensional materials, key for their future applications, and offers a route for tuning the interfacial adhesion that would allow for the transfer-enabled fabrication of van der Waals heterostructures.
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Tue 13 Feb 14:00: Securing the WebPKI in Practice: A tour of the technologies, politics and open problems
The public key infrastructure that secures the web has been around for nearly three decades. Since 2012, it has become a critical (albeit unappreciated) aspect of daily life for billions of people. In that short time, a dizzying number of technologies to improve security and privacy on the web have been designed, deployed, and, in many cases, deprecated. We’ll look at those which have become fundamental to online security, those which didn’t work out in practice, and the unsolved research problems remaining. We’ll also peek behind the curtain to see how contemporary realpolitik between countries over their ‘digital sovereignty’, profit incentives of corporate stakeholders and increasingly expansive government regulations threaten the WebPKI as it exists today.
- Speaker: Dennis Jackson, Mozilla
- Tuesday 13 February 2024, 14:00-15:00
- Venue: Webinar & GN06, Computer Laboratory, William Gates Building..
- Series: Computer Laboratory Security Seminar; organiser: Hridoy Sankar Dutta.
γ‐Ray Irradiation Significantly Enhances Capacitive Energy Storage Performance of Polymer Dielectric Films
Polymer dielectric capacitors are fundamental in advanced electronics and power grids but suffer from low energy density, hindering miniaturization of compact electrical systems. We show that high-energy and strong penetrating γ-irradiation significantly enhances capacitive energy storage performance of polymer dielectrics. γ-irradiated biaxially oriented polypropylene (BOPP) films exhibit an extraordinarily high energy density of ∼10.4 J cm−3 at ∼968 MV m−1 with an efficiency of ∼97.3%. In particular, an energy density of ∼4.06 J cm−3 with an ultrahigh efficiency of ∼98% is reliably maintained through 20,000 charge-discharge cycles under 600 MV m−1. At 125 °C, the γ-irradiated BOPP film still delivers a high discharged energy density of ∼5.88 J cm−3 with an efficiency of ∼90% at ∼770 MV m−1. Substantial improvements are also achieved for γ-irradiated cycloolefin copolymers at a high temperature of 150 °C, verifying the strategy generalizability. Experimental and theoretical analyses reveal that the excellent performance should be related to the γ-irradiation induced polar functional groups with high electron affinity in the molecular chain, which offer deep energy traps to impede charge transport. This work provides a simple and generally applicable strategy for developing high-performance polymer dielectrics.
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Eliminating Non‐Corner‐Sharing Octahedral for Efficient and Stable Perovskite Solar Cells
The metal halide [BX6]4- octahedron, where B represents a metal cation and X represents a halide anion, is regarded as the fundamental structural and functional unit of metal halide perovskites. However, the influence of the way the [BX6]4− octahedra connect to each other has on the structural stability and optoelectronic properties of metal halide perovskite is still unclear. Here, we tune and reliably characterize the octahedral connectivity, including corner-, edge-, and face-sharing, of various CsxFA1-xPbI3 (0≤x≤0.3) perovskite films through compositional and additive engineering, and with ultralow-dose transmission electron microscopy. We find that the overall solar cell device performance, the charge carrier lifetime, the open-circuit voltage, and the current density-voltage hysteresis are all improved when the films consist of corner-sharing octahedra, and non-corner sharing phases are suppressed, even in films with the same chemical composition. Additionally, we find that the structural, optoelectronic, and device performance stabilities are similarly enhanced when non-corner-sharing connectivities are suppressed. Our approach, combining macroscopic device tests and microscopic material characterization, provides a powerful tool enabling a thorough understanding of the impact of octahedral connectivity on device performance, and opens a new parameter space for designing high-performance photovoltaic metal halide perovskite devices.
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Graphene and MOF Assembly: Enhanced Fabrication and Functional Derivative via MOF Amorphisation
The integration of graphene and metal-organic frameworks (MOFs) has numerous implications across various domains, but fabricating such assemblies is often complicated and time-consuming. Herein, we presented a one-step preparation of graphene-MOF assembly by directly impregnating vertical graphene (VG) arrays into the zeolitic imidazolate framework (ZIF) precursors under ambient conditions. This approach can effectively assemble multiple ZIFs, including ZIF-7, ZIF-8 and ZIF-67, resulting in their uniform dispersion on the VG with adjustable sizes and shapes. Hydrogen defects on the VG surface are critical in inducing such high-efficiency ZIF assembly, acting as the reactive sites to interact with the ZIF precursors and facilitate their crystallisation. We further demonstrate the versatility of VG-ZIF-67 assembly by exploring the process of MOF amorphisation. Surprisingly, this process leads to an amorphous thin-film coating formed on VG (named VG-IL-amZIF-67), which preserves the short-range molecular bonds of crystalline ZIF-67 while sacrificing the long-range order. Such a unique film-on-graphene architecture maintains the essential characteristics and functionalities of ZIF-67 within a disordered arrangement, making it well-suited for electrocatalysis. In electrochemical oxygen reduction, VG-IL-amZIF-67 exhibits exceptional activity, selectivity, and stability to produce H2O2 in acid media.
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Fri 02 Feb 13:00: Group Discussion - What I wish I had Known Earlier in My Research Career
Abstract not available
- Speaker: Group Discussion
- Friday 02 February 2024, 13:00-14:00
- Venue: FW11, William Gates Building. Zoom link: https://cl-cam-ac-uk.zoom.us/j/4361570789?pwd=Nkl2T3ZLaTZwRm05bzRTOUUxY3Q4QT09&from=addon .
- Series: Energy and Environment Group, Department of CST; organiser: lyr24.
Fri 22 Mar 13:00: Title - TBC
This Cambridge Immunology and Medicine Seminar will take place on Friday 22 March 2024, starting at 1:00 pm, in the Ground Floor Lecture Theatre, Jeffrey Cheah Biomedical Centre (JCBC):
Speaker: Dr Sara Ghorashian, Honorary Senior Clinical Lecturer, University College London and Consultant Paediatric Haematologist, Great Ormond Street Hospital
Host: Professor Rahul Roychoudhuri, Professor of Cancer Immunology, University of Cambridge.
For anyone who can’t attend in person, please join the Cambridge Immunology and Medicine Seminar on Zoom Refreshments will be available following the Seminar.
This talk is part of the Immunology and Medicine Seminars series.
If you have a question about this talk, please contact Ruth Paton
- Speaker: Sara Ghorashian, Honorary Associate Professor, University College London
- Friday 22 March 2024, 13:00-14:00
- Venue: Lecture Theatre, Jeffrey Cheah Biomedical Centre, Cambridge Biomedical Campus.
- Series: Immunology and Medicine Seminars; organiser: Ruth Paton.
Fri 08 Mar 13:00: Title - TBC
The next Cambridge Immunology and Medicine Seminar will take place on Friday 8th March 2024, starting at 1:00 pm, in the Ground Floor Lecture Theatre, Jeffrey Cheah Biomedical Centre (JCBC)
Speaker: Professor Luca Gattinoni, Division of Functional Immune Cell Modulation, Leibniz Institute for Immunotherapy
Host: Professor Rahul Roychoudhuri, Professor of Cancer Immunology (Department of Pathology) and Director (non-clinical) of the CRUK Cambridge Centre Training Programme, at the University of Cambridge.
For anyone who can’t attend in person, please join the Cambridge Immunology and Medicine Seminar on Zoom:
Join Zoom Meeting: https://cam-ac-uk.zoom.us/j/89741634903?pwd=dzcxbU45NjAwQXo1dmlNMjR3V0lUUT09
Meeting ID: 897 4163 4903 Passcode: 539740
Refreshments will be available following the Seminar.
- Speaker: Luca Gattinoni, Division of Functional Immune Cell Modulation, Leibniz Institute for Immunotherapy (LIT), Regensburg, Germany
- Friday 08 March 2024, 13:00-14:00
- Venue: Lecture Theatre, Jeffrey Cheah Biomedical Centre, Cambridge Biomedical Campus.
- Series: Immunology and Medicine Seminars; organiser: Ruth Paton.
Reconfigurable Growth of Engineered Living Materials
The growth of multicellular organisms is a process akin to additive manufacturing where cellular proliferation and mechanical boundary conditions, amongst other factors, drive morphogenesis. Engineers have limited ability to engineer morphogenesis to manufacture goods or to reconfigure materials comprised of biomass. Herein, a method that uses biological processes to grow and regrow magnetic engineered living materials (mELMs) into desired geometries is reported. These composites contain Saccharomyces cerevisiae and magnetic particles within a hydrogel matrix. The reconfigurable manufacturing process relies on the growth of living cells, magnetic forces, and elastic recovery of the hydrogel. The mELM then adopts a form in an external magnetic field. Yeast within the material proliferate, resulting in 259 ± 14% volume expansion. Yeast proliferation fixes the magnetic deformation, even when the magnetic field is removed. The shape fixity can be up to 99.3 ± 0.3%. The grown mELM can recover up to 73.9 ± 1.9% of the original form by removing yeast cell walls. The directed growth and recovery process can be repeated at least five times. This work enables ELMs to be processed and reprocessed into user-defined geometries without external material deposition.
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Dibromomethane Knitted Highly Porous Hyper‐Cross‐Linked Polymers for Efficient High‐Pressure Methane Storage
Hyper-cross-linked polymers (HCPs) with ultra-high porosity, superior physicochemical stability and excellent cost-effectiveness are attractive candidates for methane storage. However, the construction of HCPs with BET surface areas exceeding 3000 m2 g–1 remains extremely challenging. In this work, a newly developed DBM-knitting method with a slow-knitting rate was employed to increase the crosslinking degree, in which dichloromethane (DCM) was replaced by dibromomethane (DBM) as both solvent and electrophilic cross-linker, resulting in highly porous and physicochemically stable HCPs. The BET surface areas of DBM-knitted SHCPs-Br are 44%–120% higher than that of DCM-knitted SHCPs-Cl using the same building blocks. Remarkably, SHCP-3-Br exhibits an unprecedentedly high porosity (SBET = 3120 m2 g–1) among reported HCPs, and shows a competitive volumetric 5–100 bar working methane capacity of 191 cm3 (STP) cm–3 at 273 K calculated by using real packing density, which outperforms sate-of-art MOFs at comparable condtions. This facile and versatile low-knitting-rate strategy enables effective improvement in the porosity of HCPs for porosity-desired applications.
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Thu 06 Jun 16:00: Title to be confirmed
Abstract not available
- Speaker: Colleen Deane, University of Southampton
- Thursday 06 June 2024, 16:00-17:00
- Venue: Hodgkin Huxley Seminar Room, Physiology builiding, Downing Site CB2 3EG.
- Series: Foster Talks; organiser: er454.
Thu 23 May 16:00: Title to be confirmed
Abstract not available
- Speaker: Stefanie Wculek, IRB (Biomedical Research Institute, Barcelona)
- Thursday 23 May 2024, 16:00-17:00
- Venue: Hodgkin Huxley Seminar Room, Physiology builiding, Downing Site CB2 3EG.
- Series: Foster Talks; organiser: er454.
Thu 09 May 16:00: Title to be confirmed
Abstract not available
- Speaker: Shankar Srinivas, Oxford University
- Thursday 09 May 2024, 16:00-17:00
- Venue: Hodgkin Huxley Seminar Room, Physiology builiding, Downing Site CB2 3EG.
- Series: Foster Talks; organiser: er454.
Thu 25 Apr 16:00: Title to be confirmed
Abstract not available
- Speaker: Laura Machesky, Department of Biochemistry, University of Cambridge
- Thursday 25 April 2024, 16:00-17:00
- Venue: Hodgkin Huxley Seminar Room, Physiology builiding, Downing Site CB2 3EG.
- Series: Foster Talks; organiser: er454.
Thu 14 Mar 16:00: Title to be confirmed
Abstract not available
- Speaker: Miguel Torres, Spanish National Center for Cardiovascular Research
- Thursday 14 March 2024, 16:00-17:00
- Venue: Hodgkin Huxley Seminar Room, Physiology builiding, Downing Site CB2 3EG.
- Series: Foster Talks; organiser: er454.
Thu 14 Mar 16:00: Title to be confirmed
Abstract not available
- Speaker: Miguel Torres, Spanish National Center for Cardiovascular Research
- Thursday 14 March 2024, 16:00-17:00
- Venue: Hodgkin Huxley Seminar Room, Physiology builiding, Downing Site CB2 3EG.
- Series: Foster Talks; organiser: er454.
Thu 29 Feb 16:00: Title to be confirmed
Abstract not available
- Speaker: Susan Ozanne, MRC, University of Cambridge
- Thursday 29 February 2024, 16:00-17:00
- Venue: Hodgkin Huxley Seminar Room, Physiology builiding, Downing Site CB2 3EG.
- Series: Foster Talks; organiser: er454.