Synthesis, Characterization, and Application of Liquid Crystal Polymers

A special issue of Polymers (ISSN 2073-4360). This special issue belongs to the section "Polymer Physics and Theory".

Deadline for manuscript submissions: 31 August 2024 | Viewed by 2166

Special Issue Editors


E-Mail Website
Guest Editor
Department of Chemical Technology and Materials Science, Rzeszow University of Technology, 35-959 Rzeszów, Poland
Interests: liquid crystals; epoxy resins; thermal analysis; thermosets; composites; smart polymers

E-Mail Website
Guest Editor
Department of Chemical Technology and Materials Science, Rzeszow University of Technology, 35-959 Rzeszów, Poland
Interests: Materials Science

Special Issue Information

Dear Colleagues,

Modern materials science is focused on the development of task-oriented structures with sophisticated and specific properties. Undoubtedly, this group of materials includes liquid-crystalline polymers (LCPs) and composites.

LCP systems combine the features of liquid crystal (LC) compounds, i.e., anisotropy of optical, dielectric, magnetic, and other properties, with those typical of polymers. Generally, LCPs are characterized by high impact strength, a high modulus of elasticity along the direction of molecular orientation, relatively low viscosity of precursors, melts, or solutions, high chemical and fire resistance, low solubility and solvent resistance, a high glass transition/melting temperature, and a low coefficient of thermal expansion. Their areas of application include, among others, coatings, the production of information storage systems, advanced optics and electro-optics, optical filters and polarizers, holographic imaging, and stationary phases for gas chromatography. ​

This Special Issue aims to present new ideas related to (i) the synthesis of new LCPs and composites, (ii) the characteristics of the specific properties of the obtained systems and methods of manipulating these properties, and (iii) potential applications. 

Dr. Maciej Kisiel
Dr. Beata Mossety-Leszczak
Guest Editors

Manuscript Submission Information

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Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Polymers is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2700 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • liquid crystallinity
  • liquid-crystalline polymers
  • oriented/organized polymers
  • mesogenic groups
  • self-reinforcement
  • smart materials
  • ordering
  • coatings

Published Papers (2 papers)

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Research

15 pages, 14023 KiB  
Article
Modification of the Dielectric and Thermal Properties of Organic Frameworks Based on Nonterminal Epoxy Liquid Crystal with Silicon Dioxide and Titanium Dioxide
by Lidia Okrasa, Magdalena Włodarska, Maciej Kisiel and Beata Mossety-Leszczak
Polymers 2024, 16(10), 1320; https://doi.org/10.3390/polym16101320 - 8 May 2024
Viewed by 581
Abstract
A nonterminal liquid crystal epoxy monomer is used to create an epoxy–amine network with a typical diamine 4,4′diaminodiphenylmethane. The plain matrix is compared to matrices modified with inorganic fillers: TiO2 or SiO2. Conditions of the curing reaction and glass transition [...] Read more.
A nonterminal liquid crystal epoxy monomer is used to create an epoxy–amine network with a typical diamine 4,4′diaminodiphenylmethane. The plain matrix is compared to matrices modified with inorganic fillers: TiO2 or SiO2. Conditions of the curing reaction and glass transition temperatures in the cured products are determined through differential scanning calorimetry and broadband dielectric spectroscopy. The curing process is also followed through optical and electrical observations. The dielectric response of all investigated networks reveals a segmental α-process related to structural reorientation (connected to the glass transition). In all products, a similar process associated with molecular motions of polar groups also appears. The matrix modified with TiO2 exhibits two secondary relaxation processes (β and γ). Similar processes were observed in the pure monomer. An advantage of the network with the TiO2 filler is a shorter time or lower temperature required for optimal curing conditions. The physical properties of cured matrices depend on the presence of a nematic phase in the monomer and nonterminal functional groups in the aliphatic chains. In effect, such cured matrices can have more flexibility and internal order than classical resins. Additional modifiers used in this work shift the glass transition above room temperature and influence the fragility index in both cases. Full article
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15 pages, 6433 KiB  
Article
The Effect of Nonterminal Liquid Crystalline Epoxy Resin Structure and Curing Agents on the Glass Transition of Polymer Networks
by Maciej Kisiel and Beata Mossety-Leszczak
Polymers 2024, 16(6), 857; https://doi.org/10.3390/polym16060857 - 21 Mar 2024
Cited by 1 | Viewed by 1178
Abstract
Modern science and technology demand a low glass transition temperature, yet one tailored to specific thermoset needs and specific to individual hardener applications. Two novel, nonterminal liquid crystalline epoxy resins (LCER) were synthesised, with their structures characterized via nuclear magnetic resonance (NMR), mass [...] Read more.
Modern science and technology demand a low glass transition temperature, yet one tailored to specific thermoset needs and specific to individual hardener applications. Two novel, nonterminal liquid crystalline epoxy resins (LCER) were synthesised, with their structures characterized via nuclear magnetic resonance (NMR), mass spectrometry (MS), and elemental analysis. Their liquid crystalline nature and thermal properties were determined using polarized optical microscopy (POM), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). A set of seven aromatic amines serving as curing agents was used to perform curing in fourteen different systems in order to assess the glass transition temperature (Tg) of the obtained polymer networks using DSC. The liquid crystalline elastomers were obtained with vitrification occurring in a low temperature range (−10–40 °C), with a more predictable outcome for amines with two aromatic rings in the structure than with one. Moreover, the resin with a core consisting of four aromatic rings produces networks with higher Tg than the three-aromatic resin. The use of nonterminal LCER allowed the lowering of the glass transition temperature of the polymers to more than 70 °C compared to a terminal analogue. This brings new possibilities of designing highly elastic yet cured polymers with potential for use in smart applications due to the LC nature of the resin. Full article
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