Thermal Characterization of Polymer-Dispersed Liquid Crystals by Differential Scanning Calorimetry

Russell, Graham M.; Paterson, Brodie; Imrie, Corrie T.; Heeks, S. K.

doi:10.1021/cm00059a029

Cited by 34 publications

(17 citation statements)

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“…The liquid crystal texture within a dispersed droplet is randomly orientated relative to other droplets giving the PDLC film an opaque appearance due to the strong scattering of light that occurs. When an electric field is applied, the directors of each droplet align parallel to the applied field, and if the refractive index of the liquid crystal is matched to that of the polymer, then the film becomes optically transparent [13][14][15].…”

Section: Introductionmentioning

confidence: 99%

“…Complete phase separation does not always occur between the two components. A small fraction of mesogen remains in the polymer matrix, while prepolymer or partially cured polymer is present in small amounts in the liquid crystal droplets [15,16]. Incomplete phase separation has several significant effects on the properties of the PDLC.…”

Section: Introductionmentioning

confidence: 99%

“…Incomplete phase separation has several significant effects on the properties of the PDLC. Low-molecular-weight liquid crystals will generally act as a plasticizer in a polymer matrix and hence reduce the glass transition temperature of the matrix [15,17]. The liquid crystal can cause a change in the refractive index of the polymer matrix, which in turn would lead to less clarity in the transparent state when an electric field is applied [15].…”

Section: Introductionmentioning

confidence: 99%

“…A prepolymer or partially cured polymer present in the liquid crystal droplets leads to a reduction in the clearing temperature. For phase separation that was induced using UV light, the presence of an initiator in the liquid crystal droplets would have a similar effect [15]. The morphology of liquid crystal droplets is affected by many variables, the principle factors being liquid crystal and polymer composition, cure temperature, and the rate of curing.…”

Section: Introductionmentioning

confidence: 99%

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Thermal and Optical Characterization of Polymer-Dispersed Liquid Crystals

Shanks

Staszczyk

2012

International Journal of Polymer Science

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Liquid crystals are compounds that display order in the liquid state above the melting temperature and below the mesogenic isotropic temperature. Polymer-dispersed liquid crystals (PDLCs) are composite materials in which liquid crystalline material is dispersed within a polymer matrix to form micron-sized droplets. The aim was to prepare several cholesteryl esters or alkoxybenzoic acid PDLCs and characterise thermal and optical properties. Differential scanning calorimetry and polarized optical microscopy were employed. The matrix polymer was a one-component UV-curable epoxy-acrylate resin. PDLCs were formed through entropy controlled phase separation resulting from UV-initiated crosslinking. The liquid crystals, both as mesogenic moieties and as dispersed droplets, exhibited various textures according to their molecular order and orientation. These textures formed in constrained regions separated by phase boundaries that occurred at temperatures characteristic of each liquid crystal used. The PDLC phase transitions occurred at temperatures lower than those exhibited by the mesogenic components in the neat state.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Thermal and Optical Characterization of Polymer-Dispersed Liquid Crystals

Shanks

Staszczyk

2012

International Journal of Polymer Science

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“…Note that the values of A determined from the data shown in Table 3 were slightly higher than the value reported in the literature [25]. However, these values are much higher than the typical values ranging from 10 to 20 measured for a thermally cured system [18,19].…”

Section: Resultsmentioning

confidence: 51%

Thermoplastic polymer‐dispersed liquid crystals prepared from solvent‐induced phase separation with predictions using solubility parameters

Chen

Shanks

2007

Liquid Crystals

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The optical effects of liquid crystals can be realized when the mesogens are dispersed in a supporting and stabilizing polymer phase. Thermoplastics were chosen for their structural reversibility and ease of fabrication of polymer-dispersed liquid crystals (PDLCs) from solution via solvent-induced phase separation (SIPS). The component match and tuning in PDLCs was achieved in a common solvent through predictions of solubility parameters. The PDLCs were first prepared using SIPS and were then exposed to thermal treatments on a hot stage polarizing microscope or in a differential scanning calorimeter. At elevated temperatures the polymer and mesogen may become miscible, while upon cooling thermally induced phase separation (TIPS) should occur, preferably above the isotropic-nematic transition temperature. The nematic phase existed within disperse phase droplets that were stabilized and supported by the matrix polymer. The temperature range of the nematic phase was extended in the PDLC configuration. The droplet size was important for liquid crystalline optical behaviour. Polymer-mesogen interactions, identified through solubility parameters, were important in ensuring sufficient but not coarse phase separation.

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Thiol–enes: Chemistry of the past with promise for the future

Hoyle

Lee

Roper

2004

J. Polym. Sci. A Polym. Chem.

1,356

1,472

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ABSTRACT:The photopolymerization of mixtures of multifunctional thiols and enes is an efficient method for the rapid production of films and thermoset plastics with unprecedented physical and mechanical properties. One of the major obstacles in traditional freeradical photopolymerization is essentially eliminated in thiol-ene polymerizations because the polymerization occurs in air almost as rapidly as in an inert atmosphere. Virtually any type of ene will participate in a free-radical polymerization process with a multifunctional thiol. Hence, it is possible to tailor materials with virtually any combination of properties required for a particular application.

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Thermal Characterization of Polymer-Dispersed Liquid Crystals by Differential Scanning Calorimetry

Cited by 34 publications

References 1 publication

Thermal and Optical Characterization of Polymer-Dispersed Liquid Crystals

Thermal and Optical Characterization of Polymer-Dispersed Liquid Crystals

Thermoplastic polymer‐dispersed liquid crystals prepared from solvent‐induced phase separation with predictions using solubility parameters

Thiol–enes: Chemistry of the past with promise for the future

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