Bulletin of the American Physical Society
APS March Meeting 2022
Volume 67, Number 3
Monday–Friday, March 14–18, 2022; Chicago
Session T17: Optics and Photonics in Polymers and Soft Matter IFocus Recordings Available
|
Hide Abstracts |
Sponsoring Units: DPOLY DSOFT DAMOP Chair: Chaitanya Ullal, Rensselaer Polytechnic Institute Room: McCormick Place W-184BC |
Thursday, March 17, 2022 11:30AM - 12:06PM |
T17.00001: "Ultra-bright, Small and Photostable Nanoprobes for Optical Super-Resolution Microscopy Imaging of Nanostructured Soft Materials" Invited Speaker: Uli B Wiesner Optical super-resolution microscopy (OSRM) methods provide fluorescence imaging capabilities below the diffraction limit of light. While this set of advanced techniques has seen rapid application to biological questions, their adoption in soft matter has been considerably slower. This is in large part due to the lack of probes able to orthogonally label, and provide super-resolution images of, e.g. nanoscopic structures in the condensed state of soft matter. Here we introduce a novel class of ultrasmall aluminosilicate nanoparticles (aC’ dots) employed in stochastic optical reconstruction microscopy (STORM) using a single excitation source and without requiring specific aqueous imaging buffers. Tailoring both encapsulated dye and aC’ dot surface chemistry affords straightforward protocols for multicolor OSRM on diffraction-limited and chemically dissimilar features, paving the way for multiplexed OSRM analysis, e.g. of polymer nanostructures in the condensed state. |
Thursday, March 17, 2022 12:06PM - 12:18PM |
T17.00002: Informed Design of Polymer-Selective Nanoprobes for Optical Super-Resolution Microscopy Dana V Chapman, Ulrich Wiesner Optical super-resolution microscopy (OSRM) facilitates optical imaging below the diffraction limit of light, thus enabling spatial characterization on the nanoscale. OSRM provides complementary information to conventional polymer characterization tools like electron and scanning-probe microscopies, such as in-situ subsurface probing and noninvasive chemical distinction. Thus far, OSRM imaging of condensed-state systems has relied almost exclusively on fluorophores designed for biological systems (i.e., largely aqueous environments). To translate the advantages of OSRM to polymer science, it is desirable to develop fluorescent probes—here, ultrasmall core–shell nanoparticles called aluminosilicate Cornell prime (aC’) dots—that orthogonally label polymer components in non-aqueous environments. We employ both active chemical and passive physical compatibilization strategies to promote selective aC’ dot targeting of specific polymer nanodomains in model block copolymer (BCP) thin films. This approach realizes nanoscale chemical distinction of different blocks simultaneously in one system using stochastic optical reconstruction microscopy (STORM). Self-assembled BCPs exhibit densely contiguous features on the order of 10s of nanometers, rendering probe specificity and performance all the more important. Multifunctional aC’ dots surmount this barrier by enhancing the photophysical properties of encapsulated organic dyes, increasing photon output while maintaining a low duty cycle. That is, tuning both the core and shell of our aC’ dots enables enhanced resolution in STORM while maintaining a high degree of chemical selectivity, even for self-assembly in different organic solvents. This research lays the groundwork for future studies elucidating compositional and behavioral relationships in polymer systems, using complementary insights from OSRM to strengthen the scientific community’s understanding of condensed-state systems. |
Thursday, March 17, 2022 12:18PM - 12:30PM |
T17.00003: Correlative nanomechanical mapping and super-resolution optical microscopy in PDMS/PMMA interpenetrating networks Tyler R Heyl, Anthony Silvaroli, Jeremy Beebe, Dongchan Ahn, Shane Mangold, Kenneth R Shull, Muzhou Wang Efforts in polymer compatibilization aim to overcome macrophase separation, which leads to poor mechanical properties in polymer blends. Interpenetrating polymer networks (IPNs) increase the compatibility of polymers by kinetically trapping the microstructure, resulting in stronger, tougher materials. A common assumption in IPNs is that complete phase separation occurs, but this assumption has not been rigorously tested. We investigate the molecular distribution of the opposing polymers within the microstructure by correlating peak force quantitative nanomechanical mapping (PF-QNM) with super-resolution optical microscopy (SROM) in PDMS/PMMA IPNs to directly relate mechanical modulus to PDMS fraction in each phase. Images from PF-QNM are generated by extracting the modulus from different locations on the sample. For SROM, a photoswitchable dye is labeled on the PDMS molecules, thus providing a measure of PDMS concentration throughout the sample. These two techniques are then spatially correlated, showing that incomplete phase separation occurs. PF-QNM/SROM correlative imaging is an effective tool for quantifying compatibility in multi-component polymer materials. |
Thursday, March 17, 2022 12:30PM - 12:42PM |
T17.00004: Tunable Optical Gratings and Mechanochromic surfaces by Wrinkling of Plasma-Oxidised PDMS Annabelle Tan, Luca Pellegrino, Joao T Cabral We report strain-modulated uni- and multi-axial phase gratings induced by wrinkling of plasma-oxidised polydimethylsiloxane (PDMS). While plasma exposure yields a glassy skin with high modulus contrast compared to bulk PDMS, it inherently results in a gradient conversion profile emanating from the top film interface. We examine and quantitatively model the consequences of this gradient layer on the optical properties of the resulting strain-tuneable phase gratings. We then develop and validate a surface reconstruction methodology based on the grating diffraction pattern, extending to the high deformation regimes and to 2D gratings. The surfaces display structural color and we demonstrate that sub-micron structures can efficiency discretise colors, with tuneable properties depending on strain, skin thickness and viewing angles. |
Thursday, March 17, 2022 12:42PM - 12:54PM |
T17.00005: Switchable Soft Photonic Bio-Adhesives Minkyu Kim, Daria Bukharina, Dhriti Nepal, Timothy J Bunning, Vladimir V Tsukruk Here, we present switchable soft photonic bio-adhesives with real-time colorimetric monitoring of reversible adhesion behavior by employing a responsive bio-photonic matrix with the dynamic hydrogen-bonding network. Synergetic materials sequencing creates a switchable structural color appearance directly correlated with both adhesion and mechanical strength in a highly reversible manner. The responsive soft photonic materials, having a strong physically hydrogen bonded chiral nematic structure, can dynamically change their adhesion and mechanical strength owed to a transition in cohesive and interfacial adhesion failure mechanism depending on the surrounding humidty. Concurrently, the dynamic hydrogen bonding feature enabled the reversible vivid color appearance shift from blue to red and transparent and vice versa, allowing tunable pitch distance of cholesteric organization. Such unique switchable strength-adhesion-iridescence triple-coupling phenomenon has never been reported before and is further applied as super-strong reversible bio-adhesives for synthetic/biological surfaces with quick remotely-provoked sticky/non-sticky transitions for biomedical and biosensing applications. |
Thursday, March 17, 2022 12:54PM - 1:06PM |
T17.00006: Bright, non-iridescent structural coloration from clay mineral nanosheet suspensions Jon Otto Fossum, Paulo Henrique O Michels Brito, Josef Breu, Volodymyr Dudko, Daniel R Wagner, Paul Markus, Georg Papastavrou, Leander Michels Structural colors originate by constructive interference following reflection and scattering of light from nanostructures with periodicity comparable to visible light wavelengths. Bright and non-iridescent structural colorations are highly desirable, but they were limited to a handful of materials that could hardly be called sustainable. Here we demonstrate that bright non-iridescence structural coloration easily and rapidly can be achieved from suspended two-dimensional nanosheets of a clay mineral. We show that brightness is enormously improved by using double clay nanosheets, thus optimizing the clay refractive index that otherwise hampers structural coloration from such systems. Intralayer distances, and thus the structural colors, can be precisely and reproducibly controlled by clay concentration and ionic strength independently, and non-iridescence is readily and effortlessly obtained in this system. Embedding such clay designed nanosheets in recyclable solid matrices could provide tunable vivid coloration and mechanical strength and stability at the same time, thus opening a new venue for the sustainable penetration of structural coloration to everyday life. |
Thursday, March 17, 2022 1:06PM - 1:18PM |
T17.00007: Origin of thickness-dependent circularly polarized luminescence in chiral polymer films Nikita V Tepliakov, Jessica Wade, Matthew J Fuchter, Johannes Lischner, Arash A Mostofi An initially achiral polymer, when blended with small chiral molecules, can adopt a chiral structure and become optically active. The resulting material exhibits circularly polarized luminescence (CPL), which has numerous applications in display technologies, optical quantum computing, and biosensing. A recent experimental study reported fabrication of a chiral polymer film with exceptionally large CPL [L. Wan et al. ACS Nano 13, 8099 (2019)]. Interestingly, this CPL can be made to invert handedness by merely changing the thickness of the film. Here, we present a comprehensive analytical theory that explains this unusual dependence of the polymer’s CPL on film thickness. The chiral structure of the polymer is modelled as helically twisted fibres, in which circularly polarized light is emitted by excitations propagating along the twisted polymer chains. We reveal that the thickness dependence of CPL stems from the interplay between the spatial dispersion of light and strong delocalization of excitons in the polymer. We further explore the possibility of maximising CPL through alignment of the polymer chains within the film. The results of our study will prove useful in designing chiral polymers with tunable chiroptical properties for photonic applications. |
Thursday, March 17, 2022 1:18PM - 1:30PM |
T17.00008: Launching a Tug-of-War between Bacteria and Bi-phase Droplets Hari Vijayamohanan, Hannah Feldstein, Jan F Totz, Alberto Concellón, Jie Li, Mathias Kolle, Timothy Swager The development of rapidly deployable, point of care sensors for detecting bacteria is necessitated by the ever- present and serious public health threat they continue to pose. However, the ability to discern between dead and live populations or quantifying their viability remains a non-trivial challenge to address. Here, we develop simple droplet based optical micro-transducers that can not only readily distinguish between live and dead bacteria but are also capable of gauging the metabolic levels of individual cells by tracking the time dependent force generated by a bacterium with sub piconewton resolution. We engineer the mesogen ordering in complex colloidal droplets comprising of immiscible liquid crystal (LC) and fluorocarbon phases, to create topological singularities for the selective localization of mannose functionalized polymer surfactants for conjugation with Escherichia coli cells. The asymmetry in density induced by the two-phase morphology induces a dynamic tug-of-war between the torque applied by the swimming bacteria and opposing gravitational forces. This dynamic interaction and the underlying mechanism are investigated through controlled experiments and modelling. These results provide a demonstration of tunable liquid systems that deliver robust optical responses via chemical coupling with biological organisms. They find utility in the development of both rapidly deployable pathogen sensing systems and biologically powered micro-actuator systems. |
Thursday, March 17, 2022 1:30PM - 1:42PM |
T17.00009: Electro-optics and material properties of oblique helicoidal cholesteric tested at oblique incidence of light Olena S Iadlovska, Kamal Thapa, Mateusz Mrukiewicz, Hari K Bisoyi, Daniel A Patterson, Ewan Cruickshank, Grant Strachan, John M Storey, Corrie T Imrie, Quan Li, Sergij V Shiyanovskii, Oleg D Lavrentovich Unique electro-optics of the oblique helicoidal cholesteric (ChOH) stem from its heliconical director structure with a pitch and a cone angle that are both dependent on the applied electric field [1]. The field preserves the single harmonic nature of the director modulation and tunes ChOH pitch in a broad spectral range as demonstrated previously for the normal incidence of light [2]. In this work, we explore electro-optics of the ChOH for an oblique incidence of light. Full pitch periodicity produces first order diffraction with wide bandwidth and total reflection at large angles of the oblique incidence. Diffraction at the half-pitch periodicity shows red and blue shifted spectra for the beams polarized in the plane of incidence and along the perpendicular direction, respectively. The cone angle, as well as other material properties such as off-field cholesteric pitch, a critical field of unwinding the ChOH structure, and dispersion of refractive indices are all measured by exploring the diffraction spectra. Unique material properties revealed by the diffraction from the ChOH are attractive for applications such as electrically tunable band-pass filters, mirrors, and beam-steering devices. The work is supported by NSF grant ECCS-1906104. |
Thursday, March 17, 2022 1:42PM - 1:54PM |
T17.00010: Directed self-assembly and post assembly modification of polymerizable blue-phase single crystals Kushal Bagchi, Tadej Emeršič, Juan De Pablo, Paul Nealey Blue-phases are soft and stimuli responsive photonic crystals that are attractive for a broad range of optoelectronic applications. Despite their attractive properties, polycrystallinity has limited the applicability of blue-phases. Previous studies have shown that chemical patterns consisting of alternating homeotropic and planar regions can be used to nucleate and grow ideal, single crystals of blue-phases. These studies however were restricted to a single model mixture (MLC-2142 and S-811) that exhibits blue-phases over a narrow temperature window of a few kelvin. Here we demonstrate that chemical patterns can be used to grow single crystals of a photopolymerizable blue-phase. By combining directed self-assembly and photopolymerization we create single crystalline blue-phase gels that are stable across a broad temperature window; most importantly the BPs states are retained at room temperature. We demonstrate that the blue-phase single crystalline gels can be reversibly switched between states that reflect light at different wavelength. We wash out the unpolymerized components of the gel with solvent and refill with new liquids thereby inducing shrinkage and swelling of the blue-phase unit cell. We discuss attempts to create a bi-continuous morphology by refilling and photopolymerizing styrene inside the blue-phase scaffold. |
Thursday, March 17, 2022 1:54PM - 2:06PM |
T17.00011: Concave Paraboloid Liquid Crystal Microlenses with Integrated Pancharatnam–Berry Phase Kelum Perera Aspheric lenses reduce aberration and provide sharper images with improved spot size compared to spherical lenses. Here, we demonstrate that applying shear flow can produce plano-concave liquid crystal lens arrays with paraboloid aspheric profiles. The focal length of individual lenses, with a 0.2mm aperture can be tuned by changing the chiral dopant concentrations. The focal length of these microles arrays are sensitive to the polarization state of the incoming light [1,2]. The microlenses are stabilized by photopolymerizing with 6 wt.% of reactive monomer added to the liquid crystal mixture. We discuss optical properties and the potential tunability of these polymer-stabilized lenses in magnetic and electric fields [3]. |
Thursday, March 17, 2022 2:06PM - 2:18PM |
T17.00012: Mesoscale Simulations of Liquid Crystalline Diblock Copolymers Austin Meng Side-chain liquid crystal (SCLC) diblock copolymers possess the characteristics of both block copolymers and liquid crystalline polymers, a combination that makes them useful for membrane separation applications and as responsive materials. Currently, there are a lack of coarse-grained molecular models that effectively capture block copolymer self-assembly and ordering of liquid crystals. We have developed a mesoscale model that we are using to study both isotropic-to-nematic and order-disorder phase transitions of SCLC diblock copolymers. We have studied the interference between the order to disorder transition of the block copolymer phases and the isotropic to nematic transition of the liquid crystal phases, finding that the nematic phase suppresses the formation of phases without at least one direction of symmetry. Additionally, we characterize how the chain conformations change as we move through the phase transitions, finding that the orientation of the chains relative to the nematic director changes as a function of the polymer composition. |
Thursday, March 17, 2022 2:18PM - 2:30PM |
T17.00013: Study of Nonlinear Optical Properties of Gold Nanoparticles Dispersed in Degenerate and Oriented Nematic Liquid Crystals Shengwei Wang, Changshuo Fu, Mohamed Amine Gharbi, Chandra Yelleswarapu Gold nanoparticles (AuNPs) come in various sizes and shapes. Their optical properties arise from surface plasmon resonance, collective excitation/oscillation of conduction electrons. The study of the nonlinear optical properties of these materials is essential for photonic and biomedical applications. On the other hand, liquid crystals have found useful applications in many fields because they can serve as a reconfigurable template to arrange and orient particles into ordered structures. They have been employed to guide nanoobjects into functional three-dimensional materials. In this work we studied the structural and nonlinear optical properties of 20 nm AuNPs that are dispersed in degenerate (non-oriented) and oriented nematic liquid crystals (NLCs) using polarizing microscopic technique and optical Z-scan technology, respectively. Polarizing microscopic images show AuNPs dispersing continuously in oriented NLCs while aggregating in degenerate NLCs. Nonlinearities are studied by curve fitting from Z-scan data to get nonlinear absorption coefficients and we considered three aspects: concentration of AuNPs, pulse laser frequency, and laser intensity. Our experiments demonstrated that AuNPs in oriented NLCs have stronger absorption, linear and nonlinear absorption coefficient of it is about twice larger than AuNPs in degenerate NLCs. Also, sample with low gold concentration, by weight percentage, shows the better nonlinearity. |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700