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Professor Georg Mehl

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Georg Mehl

Professor of Organic and Materials Chemistry


A Compact Full 2π Flexoelectro‐Optic Liquid Crystal Phase Modulator (2020)
Journal Article
Wang, X., Fells, J. A. J., Shi, Y., Ali, T., Welch, C., Mehl, G. H., …Elston, S. J. (in press). A Compact Full 2π Flexoelectro‐Optic Liquid Crystal Phase Modulator. Advanced Materials Technologies, https://doi.org/10.1002/admt.202000589

Wavefront shaping, which is often achieved using liquid crystal (LC) spatial light modulators, is particularly important for a wide range of applications including laser microfabrication and micromanipulation, microscopy, and quantum optics. In this... Read More about A Compact Full 2π Flexoelectro‐Optic Liquid Crystal Phase Modulator.

Chirality enhancement in macro-chiral liquid crystal nanoparticles (2020)
Journal Article
Yu, H., Welch, C., Qu, W., Schubert, C. J., Liu, F., Siligardi, G., & Mehl, G. H. (2020). Chirality enhancement in macro-chiral liquid crystal nanoparticles. Materials Horizons, 7(11), 3021-3027. https://doi.org/10.1039/d0mh01274b

The amplification of molecular chirality by metal nanoparticles (NPs) is an important and rapidly evolving field in nanomaterial research with wide applications in smart materials, catalysis, and solvent-solute interactions. Here we present the resul... Read More about Chirality enhancement in macro-chiral liquid crystal nanoparticles.

Millisecond Optical Phase Modulation Using Multipass Configurations with Liquid-Crystal Devices (2020)
Journal Article
Jin, Y., Elston, S. J., Fells, J. A., Booth, M. J., Welch, C., Mehl, G. H., & Morris, S. M. (2020). Millisecond Optical Phase Modulation Using Multipass Configurations with Liquid-Crystal Devices. Physical Review Applied, 14(2), https://doi.org/10.1103/physrevapplied.14.024007

We present two configurations for analog 0 to 2π optical phase modulation using liquid crystals (LCs), each of which achieve switching times that are 1 ms or less. One configuration is based on the switching behavior of a so-called nematic pi cell, a... Read More about Millisecond Optical Phase Modulation Using Multipass Configurations with Liquid-Crystal Devices.

Self-Assembly and Temperature-Driven Chirality Inversion of Cholesteryl-Based Block Copolymers (2020)
Journal Article
Krishnasamy, V., Qu, W., Chen, C., Huo, H., Ramanagul, K., Gothandapani, V., …Liu, F. (2020). Self-Assembly and Temperature-Driven Chirality Inversion of Cholesteryl-Based Block Copolymers. Macromolecules, 53(11), 4193-4203. https://doi.org/10.1021/acs.macromol.9b02264

Block copolymers (BCPs), comprising a poly(methyl methacrylate) (PMMA) block and a poly(cholesteryloxyhexyl methacrylate) (PChMA) block, were synthesized via reversible addition–fragmentation chain transfer polymerization. The self-assembly of the li... Read More about Self-Assembly and Temperature-Driven Chirality Inversion of Cholesteryl-Based Block Copolymers.

Transmissive flexoelectro-optic liquid crystal optical phase modulator with 2π modulation (2020)
Journal Article
Wang, X., Fells, J. A. J., Ali, T., Lin, J., Welch, C., Mehl, G. H., …Elston, S. J. (2020). Transmissive flexoelectro-optic liquid crystal optical phase modulator with 2π modulation. AIP Advances, 10(5), https://doi.org/10.1063/5.0009630

In this paper, we demonstrate analog phase modulation in a transmissive configuration using the flexoelectro-optic effect in short-pitch chiral nematic liquid crystal (LC) devices. Two different modes are considered, both of which are shown to genera... Read More about Transmissive flexoelectro-optic liquid crystal optical phase modulator with 2π modulation.

Temperature dependence of bend elastic constant in oblique helicoidal cholesterics (2020)
Journal Article
Iadlovska, O. S., Babakhanova, G., Mehl, G. H., Welch, C., Cruickshank, E., Strachan, G. J., …Shiyanovskii, S. V. (2020). Temperature dependence of bend elastic constant in oblique helicoidal cholesterics. Physical Review Research, 2(1), https://doi.org/10.1103/physrevresearch.2.013248

Elastic moduli of liquid crystals, known as Frank constants, are of quintessential importance for understanding fundamental properties of these materials and for the design of their applications. Although there are many methods to measure the Frank... Read More about Temperature dependence of bend elastic constant in oblique helicoidal cholesterics.

Probing molecular ordering in the nematic phases of para-linked bimesogen dimers through NMR studies of flexible prochiral solutes (2020)
Journal Article
Heist, L. M., Samulski, E. T., Welch, C., Ahmed, Z., Mehl, G. H., Vanakaras, A. G., & Photinos, D. J. (in press). Probing molecular ordering in the nematic phases of para-linked bimesogen dimers through NMR studies of flexible prochiral solutes. Liquid crystals, 1-16. https://doi.org/10.1080/02678292.2019.1711214

The quadrupolar splittings of perdeuteriated n-decane dissolved in nematic phases formed by mesogenic dimers of the CBnCB series, for n = 7,9,10,11, are measured throughout the entire temperature range of these phases. These results are reported toge... Read More about Probing molecular ordering in the nematic phases of para-linked bimesogen dimers through NMR studies of flexible prochiral solutes.

Macroscopic chirality of twist-bend nematic phase in bent dimers confirmed by circular dichroism (2019)
Journal Article
Stevenson, W. D., Zeng, X., Welch, C., Thakur, A. K., Ungar, G., & Mehl, G. H. (2020). Macroscopic chirality of twist-bend nematic phase in bent dimers confirmed by circular dichroism. Journal of materials chemistry. C, 8, 1041-1047. https://doi.org/10.1039/c9tc05061b

Many achiral bent molecules and some polymers with such repeat units exhibit a liquid crystal phase transition between a conventional nematic (N), and a second nematic (Nx) with periodically modulated orientation. Theory predicts several possible str... Read More about Macroscopic chirality of twist-bend nematic phase in bent dimers confirmed by circular dichroism.

A cholesteric liquid crystal device having stable uniform lying helix structure (2019)
Journal Article
Yip, W., Welch, C., Mehl, G. H., & Wilkinson, T. D. (2020). A cholesteric liquid crystal device having stable uniform lying helix structure. Journal of Molecular Liquids, 299, https://doi.org/10.1016/j.molliq.2019.112141

A cholesteric liquid crystal device having the uniform lying helix (ULH) structure shows stable and reversible characteristics and it has been demonstrated for the analogue modulation in 10 micro-second response time at room temperature. The device c... Read More about A cholesteric liquid crystal device having stable uniform lying helix structure.

Soft modes of the dielectric response in the twist-bend nematic phase and identification of the transition to nematic splay bend phase in the CBC7CB dimer (2019)
Journal Article
Merkel, K., Kocot, A., Mehl, G. H., & Welch, C. (2019). Soft modes of the dielectric response in the twist-bend nematic phase and identification of the transition to nematic splay bend phase in the CBC7CB dimer. Physical chemistry chemical physics : PCCP, https://doi.org/10.1039/c9cp04952e

The dielectric spectra of the twist–bend nematic phase (NTB) of (the bent-shaped) achiral liquid-crystal dimer 1”-,7”-bis(4-cyanobiphenyl-4’-yl) heptane (CB7CB) are studied for the determination of the different relaxation modes. Two molecular proces... Read More about Soft modes of the dielectric response in the twist-bend nematic phase and identification of the transition to nematic splay bend phase in the CBC7CB dimer.