Thermal and optical behavior of poly(ethylene-b-ethylene oxide) block copolymer dispersed liquid crystals blends

Carrasco‐Hernandez, Sheyla; Gutierrez, Junkal; Cano, Laida; Tercjak, Agnieszka

doi:10.1016/j.eurpolymj.2015.11.019

Cited by 8 publications

(2 citation statements)

References 38 publications

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“…This fact can be explained, on the one hand, by taking into account that as it is known from previous work , EBBA liquid crystal is more miscible with PE blocks than with PEO blocks, consequently EBBA liquid crystal was positioned in the PE block domains. On the other hand, the EBBA nematic liquid crystal chemical structure could have also an influence on the self‐assembly process, since, as pointed out before, it affects the electrospinning processing conditions.…”

Section: Resultsmentioning

confidence: 86%

Optimization of the electrospinning processing‐window to fabricate nanostructured PE‐b‐PEO and hybrid PE‐b‐PEO/EBBA fibers

Carrasco‐Hernandez

Gutierrez

Peponi

et al. 2017

Polymer Engineering & Sci

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An electrospinning technique is used to obtain poly(ethylene-b-ethylene oxide) block copolymer (PE-b-PEO) fibers. Optimization of the electrospinning processing-window is carried out by varying the concentration of the block copolymer solution and playing with three different electrospinning parameters, applied voltage, solvent and block copolymer solution flow rate. The influence of the concentration of the block copolymer solution over the length and diameter of the fibers is mainly studied and results indicate that the optimum conditions to fabricate PE-b-PEO block copolymer fibers are concentrations between 45 and 47 wt% of PE-b-PEO block copolymer and chloroform/DMF mixture ratio of 4:1 and 5:1. Moreover, low solvent and block copolymer solution flow rates led to the longest and widest fibers. Hybrid fibers are also fabricated modifying PE-b-PEO block copolymer fibers with low molecular weight N-(4-ethoxybenzylidene)24butylaniline (EBBA) nematic liquid crystal using coaxial electrospinning technique. The morphology of the fabricated fibers is investigated from micro to nanoscale. Atomic force microscopy (AFM) results show selforganization of investigated PE-b-PEO and hybrid PE-b-PEO/EBBA fibers on the nanometric scale, which make them interesting from the point of view of novel applications as template materials.

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Section: Resultsmentioning

confidence: 86%

Optimization of the electrospinning processing‐window to fabricate nanostructured PE‐b‐PEO and hybrid PE‐b‐PEO/EBBA fibers

Carrasco‐Hernandez

Gutierrez

Peponi

et al. 2017

Polymer Engineering & Sci

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“…The quintessence of monitoring the kinetics of thermally initiated processes is to establish a mathematical relationship between the process rate, extent of conversion, and the temperature . Kinetic and thermal analysis of polymers can be investigated via any of the following thermal analysis techniques: dynamic mechanical analysis, infrared spectroscopy, differential scanning calorimetry (DSC), dilatometry, and thermogravimetric analysis (TGA) . The most utilized amongst the aforementioned techniques are the DSC and TGA .…”

Section: Introductionmentioning

confidence: 99%

Thermogravimetric characterization of ex situ polymethacrylate (EDMA‐co‐GMA) monoliths

Acquah

Moy

Anwar³

et al. 2017

Can J Chem Eng

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The thermo-molecular mechanisms associated with free radical synthesis of polymethacrylate monoliths offer an effective pathway to tune their pore characteristics. In this work, thermogravimetric analyses were used for ex situ characterization of polymethacrylate monoliths synthesised from ethylene glycol dimethacrylate (EDMA) and glycidyl methacrylate (GMA). Apparent activation energies of the polymeric monoliths were determined by using Ozawa-Flynn-Wall (OFW) and Kissinger-Akahira-Sunose (KAS) isoconversional methods. The number of degradation stages for the polymers were observed to be as follows: homopolymeric GMA and EDMA (2 degradation stages each) and polymeric EDMA-co-GMA monoliths (3 degradation stages). The relationship between apparent activation energy and extent of conversion showed that the degradation of monoliths is based on a complex multi-step reaction rather than a single reaction model. Kinetic parameters showed that an increase in the composition of EDMA and GMA above 20 % significantly enhances the thermal stability of polymeric EDMA-co-GMA monoliths under elevated non-isothermal conditions. E40/G60 and E60/G40 monoliths were identified as the most thermally stable monoliths from the kinetic analyses.

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Thermophysical and Structural Properties of Polymer/Liquid Crystal Systems Using Polysiloxanes

Gogibus

Bouberka

Bedjaoui

et al. 2016

Encyclopedia of Analytical Chemistry

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This article deals with polymer dispersed liquid crystals (PDLCs) using polysiloxanes and low‐molecular‐weight liquid crystals (LCs). These composite materials exhibit generally a film texture consisting of nearly spherical microdomains filled with LC molecules and dispersed in a solid polymer matrix. These compounds are interesting because they raise a number of still unresolved fundamental questions, they lead to applications in the market of display devices and switchable windows and potential applications are foreseen in telecommunications. Applications of these systems are based essentially on their electrooptical responses when they are activated with an electric field. In the common situation of normal mode conditions, PDLC films are initially opaque but they become transparent to incident light when an electric field is applied. Understanding the electrooptical responses requires a detailed investigation of thermophysical properties and morphology to quantify the miscibility parameters and identify textures under various conditions of temperature and composition. This is the first step toward establishing correlations with the electrooptical properties and in particular understanding the variation of light transmission through the film before (off‐state) and after application of the field (on‐state).This work gives a detailed description of thermophysical and morphology properties in polymer/LC systems made of linear monodisperse polysiloxanes and nematic LCs. Two different polysiloxanes were used: poly(dimethylsiloxane) or PDMS and poly(methylphenylsiloxane) or PMPS with different molecular weights. Likewise, two model LCs were employed: the eutectic mixture of cyanoparaphenylenes E7 and the single component 4‐cyano‐4′‐n‐pentyl‐biphenyl or 5CB. A variety of experimental tools are employed to reach a good view on the film morphology, evaluate the thermophysical parameters, construct the phase diagrams, and understand the structural properties. The experimental data are rationalized in terms of a theoretical formalism adopted to the specific conditions of our systems.

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Thermal and optical behavior of poly(ethylene-b-ethylene oxide) block copolymer dispersed liquid crystals blends

Cited by 8 publications

References 38 publications

Optimization of the electrospinning processing‐window to fabricate nanostructured PE‐b‐PEO and hybrid PE‐b‐PEO/EBBA fibers

Optimization of the electrospinning processing‐window to fabricate nanostructured PE‐b‐PEO and hybrid PE‐b‐PEO/EBBA fibers

Thermogravimetric characterization of ex situ polymethacrylate (EDMA‐co‐GMA) monoliths

Thermophysical and Structural Properties of Polymer/Liquid Crystal Systems Using Polysiloxanes

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