1
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Siloxane-based side-chain liquid crystal elastomers containing allyl 4-((4-decyloxy)benzoyl)oxy)benzoate as a monomer. Polym Bull (Berl) 2022. [DOI: 10.1007/s00289-022-04507-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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2
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Effect of gold and graphene oxide nanoparticles on the thermo- and photo-actuation of monodomain liquid crystal elastomers. POLYMER 2020. [DOI: 10.1016/j.polymer.2020.122837] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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3
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Mohana K, Umadevi S. Side-chain polysiloxane liquid crystalline elastomers from non-mesogenic components. NEW J CHEM 2019. [DOI: 10.1039/c9nj03482j] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Synthesis and characterisation of two new azo-based polysiloxane liquid crystalline elastomers containing non-mesogenic monomers and different cross-linkers are described.
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Affiliation(s)
- K. Mohana
- Department of Industrial Chemistry
- School of Chemical Sciences
- Alagappa University
- Karaikudi-630 003
- India
| | - S. Umadevi
- Department of Industrial Chemistry
- School of Chemical Sciences
- Alagappa University
- Karaikudi-630 003
- India
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4
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Mechanical Manipulation of Diffractive Properties of Optical Holographic Gratings from Liquid Crystalline Elastomers. APPLIED SCIENCES-BASEL 2018. [DOI: 10.3390/app8081330] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
An appealing property of optical diffractive structures from elastomeric materials is a possibility to regulate their optical patterns and consequently also their diffractive features with mechanical straining. We investigated the effect of strain on diffraction characteristics of holographic gratings recorded in a monodomain side-chain liquid crystalline elastomer. The strain was imposed either parallel or perpendicular to the initial alignment direction of the material. At temperatures far below the nematic–paranematic phase transition, straining along the initial alignment affects mainly the diffraction pattern, while the diffraction efficiency remains almost constant. In contrast, at temperatures close to the nematic–paranematic phase transition, the diffraction efficiency is also significantly affected. Straining in the direction perpendicular to the initial alignment strongly and diversely influences both the diffraction pattern and the diffraction efficiency. The difference between the two cases is attributed to shear–stripe domains, which form only during straining perpendicular to the initial alignment and cause optical diffraction that competes with the diffraction from the holographic grating structure.
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5
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Cresta V, Romano G, Kolpak A, Zalar B, Domenici V. Nanostructured Composites Based on Liquid-Crystalline Elastomers. Polymers (Basel) 2018; 10:E773. [PMID: 30960698 PMCID: PMC6403803 DOI: 10.3390/polym10070773] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Revised: 07/09/2018] [Accepted: 07/10/2018] [Indexed: 12/17/2022] Open
Abstract
Liquid-crystalline elastomers (LCEs) are the object of many research investigations due to their reversible and controllable shape deformations, and their high potential for use in the field of soft robots and artificial muscles. This review focuses on recent studies about polymer composites based on LCEs and nanomaterials having different chemistry and morphology, with the aim of instilling new physical properties into LCEs. The synthesis, physico-chemical characterization, actuation properties, and applications of LCE-based composites reported in the literature are reviewed. Several cases are discussed: (1) the addition of various carbon nanomaterials to LCEs, from carbon black to carbon nanotubes, to the recent attempts to include graphene layers to enhance the thermo-mechanic properties of LCEs; (2) the use of various types of nanoparticles, such as ferroelectric ceramics, gold nanoparticles, conductive molybdenum-oxide nanowires, and magnetic iron-oxide nanoparticles, to induce electro-actuation, magnetic-actuation, or photo-actuation into the LCE-based composites; (3) the deposition on LCE surfaces of thin layers of conductive materials (i.e., conductive polymers and gold nanolayers) to produce bending actuation by applying on/off voltage cycles or surface-wrinkling phenomena in view of tunable optical applications. Some future perspectives of this field of soft materials conclude the review.
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Affiliation(s)
- Vanessa Cresta
- Dipartimento di Chimica e Chimica Industriale, Università di Pisa, via Moruzzi 13, 56124 Pisa, Italy.
| | - Giuseppe Romano
- Department of Mechanical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139-4307, USA.
| | - Alexej Kolpak
- Department of Mechanical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139-4307, USA.
| | - Boštjan Zalar
- Department of Condensed Matter Physics, Jozef Stefan Institute, Jamova Cesta 39, SI 1000 Ljubljana, Slovenia.
| | - Valentina Domenici
- Dipartimento di Chimica e Chimica Industriale, Università di Pisa, via Moruzzi 13, 56124 Pisa, Italy.
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6
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Milavec J, Domenici V, Zupančič B, Rešetič A, Bubnov A, Zalar B. Deuteron NMR resolved mesogen vs. crosslinker molecular order and reorientational exchange in liquid single crystal elastomers. Phys Chem Chem Phys 2016; 18:4071-7. [DOI: 10.1039/c5cp06207a] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
2H NMR spectroscopy can resolve differences in orientational order and reorientational dynamics between crosslinker and mesogen molecules in liquid single crystal elastomers.
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Affiliation(s)
- J. Milavec
- Department of Condensed Matter Physics
- J. Stefan Institute
- SI-1000 Ljubljana
- Slovenia
- Jožef Stefan International Postgraduate School
| | - V. Domenici
- Dipartimento di Chimica e Chimica Industriale
- Universitá degli studi di Pisa
- 56124 Pisa
- Italy
| | - B. Zupančič
- Department of Condensed Matter Physics
- J. Stefan Institute
- SI-1000 Ljubljana
- Slovenia
| | - A. Rešetič
- Department of Condensed Matter Physics
- J. Stefan Institute
- SI-1000 Ljubljana
- Slovenia
- Jožef Stefan International Postgraduate School
| | - A. Bubnov
- Institute of Physics
- Academy of Sciences of the Czech Republic
- Czech Republic
| | - B. Zalar
- Department of Condensed Matter Physics
- J. Stefan Institute
- SI-1000 Ljubljana
- Slovenia
- Jožef Stefan International Postgraduate School
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7
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Samui AB, Pandey S, Mishra SP. Main chain photoresponsive liquid crystalline polymer synthesized through hydrosilylation. RSC Adv 2015. [DOI: 10.1039/c5ra14818a] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Siloxane based dihydride was reacted with diallyl siloxane for designing a fast photoresponsive LC polymer system having LC phase around room temperature. The nematic LC system with fast trans–cis isomerization behaviour was observed.
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Affiliation(s)
- Asit B. Samui
- Defence Institute of Advanced Technology
- Pune-411025
- India
| | - Someshwarnath Pandey
- Polymer Science and Technology Centre
- Naval Materials Research Laboratory
- Ambernath-421506
- India
| | - Sarada P. Mishra
- Polymer Science and Technology Centre
- Naval Materials Research Laboratory
- Ambernath-421506
- India
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8
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Domenici V, Milavec J, Zupančič B, Bubnov A, Hamplova V, Zalar B. Brief overview on 2H NMR studies of polysiloxane-based side-chain nematic elastomers. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2014; 52:649-655. [PMID: 24919664 DOI: 10.1002/mrc.4092] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2014] [Revised: 05/16/2014] [Accepted: 05/17/2014] [Indexed: 06/03/2023]
Abstract
This is a brief overview on recent studies on liquid crystalline elastomers (LCEs) based on polysiloxane chain, in the form of monodomain films, selectively (2)H-labeled in different parts of the LCE samples, i.e. on the crosslinker or mesogenic units. (2)H NMR spectroscopic techniques were used to measure the temperature dependence of the quadrupolar splittings, line widths and relaxation times, T(1) and T(2). From these data, several information about the orientational order parameter, S, of various LCE fragments, thermodynamic features of the isotropic-nematic transition and main motional processes could be generalized for this type of elastomers.
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Affiliation(s)
- Valentina Domenici
- Dipartimento di Chimica e Chimica Industriale, Università di Pisa, via Risorgimento 35, 56126, Pisa, Italy
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Cifelli M, Domenici V, Veracini CA. Recent advancements in understanding thermotropic liquid crystal structure and dynamics by means of NMR spectroscopy. Curr Opin Colloid Interface Sci 2013. [DOI: 10.1016/j.cocis.2013.03.003] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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10
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11
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Gregorc M, Li H, Domenici V, Ambrožič G, Čopič M, Drevenšek-Olenik I. Optical properties of light-sensitive liquid-crystal elastomers in the vicinity of the nematic-paranematic phase transition. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2013; 87:022507. [PMID: 23496535 DOI: 10.1103/physreve.87.022507] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2012] [Indexed: 06/01/2023]
Abstract
We investigate light-induced patterning of a monodomain side-chain liquid crystal elastomer (SC-LCE) doped with light-sensitive azobenzene moiety in the temperature region close to the nematic-paranematic phase transition. We show that a strongly nonlinear relationship between the concentration of the cis isomers of the azomesogens and the refractive index modification of the material, which is characteristic for the phase transition region, results in nonmonotonous time dependence of the diffraction efficiency of a probe beam. From this effect we determine the sensitivity of the nematic transition temperature on the molar fraction of the cis isomers. The relation between the cis isomer molar fraction and nematic order also provides a possibility for recording hidden holograms, which can be made visible by cooling the sample from the paranematic to the nematic phase.
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Affiliation(s)
- Marko Gregorc
- Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, SI 1001 Ljubljana, Slovenia
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12
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Marini A, Zupančič B, Domenici V, Mennucci B, Zalar B, Veracini CA. A Photosensitive Liquid Crystal Studied by14N NMR,2H NMR, and DFT Calculations. Chemphyschem 2012; 13:3958-65. [DOI: 10.1002/cphc.201200546] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2012] [Revised: 08/28/2012] [Indexed: 11/11/2022]
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13
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Domenici V. 2H NMR studies of liquid crystal elastomers: macroscopic vs. molecular properties. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2012; 63:1-32. [PMID: 22546343 DOI: 10.1016/j.pnmrs.2011.07.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2011] [Accepted: 07/27/2011] [Indexed: 05/31/2023]
Affiliation(s)
- Valentina Domenici
- Dipartimento di Chimica e Chimica Industriale, Università di Pisa, via Risorgimento 35, 56126 Pisa, Italy.
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14
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Kinetics of Holographic Recording and Spontaneous Erasure Processes in Light-Sensitive Liquid Crystal Elastomers. MATERIALS 2012; 5:741-753. [PMID: 28817006 PMCID: PMC5458966 DOI: 10.3390/ma5050741] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/20/2012] [Revised: 03/16/2012] [Accepted: 03/22/2012] [Indexed: 12/03/2022]
Abstract
The optical mechanism for imprinting one-dimensional grating structures into thin films of a light-sensitive monodomain liquid crystal elastomer is investigated by analyzing the time dependence of optical diffraction properties. The recording kinetics shows an irregular oscillatory behavior, which is most expressed at small grating spacings and at temperatures close to the nematic-isotropic phase transition. The oscillations are attributed to the opto-mechanical response of the film, i.e., to contraction of the film during the recording process. At temperatures far below the nematic-isotropic phase transition, the spontaneous erasure kinetics exhibits exponential relaxation with relaxation time following the Arrhenius activation law. However, at temperatures close to the nematic-isotropic phase transition, the erasure process shows an interesting nonmonotonic behavior that we attribute to the non-linear relation between the concentration of the photo-transformed chemical groups and the nematic order parameter.
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15
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Cantatore V, Granucci G, Persico M. Stochastic model for photoinduced anisotropy. J Comput Chem 2012; 33:1015-22. [PMID: 22331839 DOI: 10.1002/jcc.22931] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2011] [Revised: 11/27/2011] [Accepted: 12/16/2011] [Indexed: 11/07/2022]
Abstract
We present a stochastic model for the kinetics of photoinduced anisotropy in a sample of molecular chromophores that may undergo photoisomerization. It is assumed that the chromophores do not interact among them, but are embedded in a medium that slows down the rotational diffusion. The model makes use of data about the photoinduced reorientation of the single chromophore, its photoisomerization and its rotational diffusion, that are made available by molecular dynamics simulations. For the first time such molecular scale processes are computationally connected to the development of anisotropy in a large sample and on a long time scale. A test on azobenzene shows the potentiality of the method and the interplay between photoinduced anisotropy and photoisomerization.
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Affiliation(s)
- Valentina Cantatore
- Dipartimento diChimica e Chimica Industriale, Università di Pisa, v.Risorgimento 35, I-56126 Pisa, Italy
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16
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Van Leuven P, Cantatore V, Persico M. Photo-orientation of axial molecules. Phys Chem Chem Phys 2012; 14:1957-64. [DOI: 10.1039/c2cp23128j] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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17
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Cusati T, Granucci G, Martínez-Núñez E, Martini F, Persico M, Vázquez S. Semiempirical Hamiltonian for simulation of azobenzene photochemistry. J Phys Chem A 2011; 116:98-110. [PMID: 22107348 DOI: 10.1021/jp208574q] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We present a semiempirical Hamiltonian that provides an accurate description of the first singlet and triplet potential energy surfaces of azobenzene for use in direct simulations of the excited-state dynamics. The parameterization made use of spectroscopic and thermochemical data and the best ab initio results available to date. Two-dimensional potential energy surfaces based on constrained geometry optimizations are presented for the states that are most relevant for the photochemistry of azobenzene, namely, S(0), S(1), and S(2). In order to run simulations of the photodynamics of azobenzene in hydrocarbons or hydroxylic solvents, we determined the interactions of methane and methanol with the azo group by ab initio calculations and fitted the interactions with a QM/MM interaction Hamiltonian.
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Affiliation(s)
- Teresa Cusati
- Dipartimento di Chimica e Chimica Industriale, Università di Pisa, v. Risorgimento 35, I-56126 Pisa, Italy
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18
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Gregorc M, Zalar B, Domenici V, Ambrožič G, Drevenšek-Olenik I, Fally M, Čopič M. Depth profile of optically recorded patterns in light-sensitive liquid-crystal elastomers. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2011; 84:031707. [PMID: 22060390 DOI: 10.1103/physreve.84.031707] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2011] [Indexed: 05/31/2023]
Abstract
We investigated nonlinear absorption and photobleaching processes in a liquid-crystal elastomer doped with light-sensitive azobenzene moiety. A conventional one-dimensional holographic grating was recorded in the material with the use of two crossed UV laser beams and the angular dependence of the diffraction efficiency in the vicinity of the Bragg peak was analyzed. These measurements gave information on the depth to which trans to cis isomerization had progressed into the sample as a function of the UV irradiation time. Using a numerical model that takes into account the propagation of writing beams and rate equations for the local concentration of the absorbing trans conformer, we computed the expected spatial distribution of the trans and cis conformers and the shape of the corresponding Bragg diffraction peak for different irradiation doses. Due to residual absorption of the cis conformers the depth of the recording progresses logarithmically with time and is limited by the thermal relaxation from the cis to trans conformation.
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Affiliation(s)
- Marko Gregorc
- J. Stefan Institute, Jamova 39, SI 1001 Ljubljana, Slovenia
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Bubnov A, Domenici V, Hamplová V, Kašpar M, Zalar B. First liquid single crystal elastomer containing lactic acid derivative as chiral co-monomer: Synthesis and properties. POLYMER 2011. [DOI: 10.1016/j.polymer.2011.07.046] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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20
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Chen X, Lu X, Cui K, Cui W, Wu J, Lu Q. Precipitation supramolecular complex for photoinduced anisotropic material with dual mesogenic units. POLYMER 2011. [DOI: 10.1016/j.polymer.2011.02.023] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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21
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Cusati T, Granucci G, Persico M. Photodynamics and Time-Resolved Fluorescence of Azobenzene in Solution: A Mixed Quantum-Classical Simulation. J Am Chem Soc 2011; 133:5109-23. [DOI: 10.1021/ja1113529] [Citation(s) in RCA: 126] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Teresa Cusati
- Dipartimento di Chimica e Chimica Industriale, Università di Pisa, v. Risorgimento 35, I-56126 Pisa, Italy
| | - Giovanni Granucci
- Dipartimento di Chimica e Chimica Industriale, Università di Pisa, v. Risorgimento 35, I-56126 Pisa, Italy
| | - Maurizio Persico
- Dipartimento di Chimica e Chimica Industriale, Università di Pisa, v. Risorgimento 35, I-56126 Pisa, Italy
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Lebar A, Cordoyiannis G, Kutnjak Z, Zalar B. The Isotropic-to-Nematic Conversion in Liquid Crystalline Elastomers. LIQUID CRYSTAL ELASTOMERS: MATERIALS AND APPLICATIONS 2010. [DOI: 10.1007/12_2010_103] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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