Optimization of holographic polymer dispersed liquid crystal for ternary monomers

Cho, Y H; Kim, B K; Park, K S

doi:10.1002/(sici)1097-0126(199911)48:11<1085::aid-pi235>3.0.co;2-o

Cited by 7 publications

(3 citation statements)

References 18 publications

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“…However, the reaction rate is too slow during the reaction time for P r of 5 × 10 –5 (Figure d), hence no satisfactory phase separation can be achieved. In sum, a moderate reaction probability is optimum for the phase separation performance of holographic polymer nanocomposite in good agreement with experimental reports. , …”

Section: Resultsmentioning

confidence: 99%

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Computational Insight into Phase Separation of a Thiol-Ene Photopolymer with Liquid Crystals for Holography by Dissipative Particle Dynamics Simulation

Wei

Chen

Li³

et al. 2023

Macromolecules

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Holographic polymer nanocomposites comprising liquid crystals (LCs) are produced through periodic photopolymerization-induced phase separation upon laser interference. A high degree of phase separation normally favors the holographic function which is, however, difficult to predict. Herein, we demonstrate the first example of providing computational insights into the phase separation by dissipative particle dynamics simulation. Phase separation to produce alternating polymer-rich and LC-rich regions occurs in the way that LC molecules transfer from bright to dark regions upon laser interference when the thiol-ene click reaction takes place in the bright regions. Results show that the relative segregation degree (SDr) increases with LC content when it is lower than 40 wt %, which can be correlated with the transferred amount of LC molecules from bright to dark regions. The low SDr of the system with 40 wt % LC may be ascribed to the inhibitory LC transfer by polymerization compared with the case prior to reaction. In terms of the effects of reaction probability, either too high or too low reaction probability is not favorable for phase separation due to insufficient LC transfer. Despite that no nematic LC phase is found after phase separation, this work provides initial computation insights into the mass transfer behaviors during photopolymerization-induced phase separation, which help in the development of effective strategies to improve the phase separation and performance of holographic polymer nanocomposites.

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Section: Resultsmentioning

confidence: 99%

“…In sum, a moderate reaction probability is optimum for the phase separation performance of holographic polymer nanocomposite in good agreement with experimental reports. 73,78…”

Section: Influences Of Reaction Probabilitymentioning

confidence: 99%

Computational Insight into Phase Separation of a Thiol-Ene Photopolymer with Liquid Crystals for Holography by Dissipative Particle Dynamics Simulation

Wei

Chen

Li³

et al. 2023

Macromolecules

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“…The periodic light intensity gradient resulting from holographic illumination induces mass transport of monomer into the illuminated regions and LC into the dark regions. As a consequence, polymer‐ and LC‐rich lamellas are formed with the refractive index being periodically modulated 6–10. The formation and performance of HPDLCs have been reviewed elsewhere in much greater detail 11…”

Section: Introductionmentioning

confidence: 99%

Holographic polymer‐dispersed liquid crystals using vinyloxytrimethylsilane

Jeong

Woo

Cho

et al. 2008

Polymer International

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BACKGROUND: To reduce the driving voltage of transmission holographic polymer-dispersed liquid crystals (HPDLCs), the polymer interface was modified by incorporating various amounts of vinyloxytrimethylsilane (VOTMS) monomer to the conventional grating formulation based on polyurethane acrylate (PUA). RESULTS: With the addition of increasing amounts of VOTMS, the contact angle of the film and the droplet size of the liquid crystal (LC) monotonically increased, implying that the VOTMS segments of the polymer are preferentially exposed to the interfaces and provide greater immiscibility with LC molecules. The operating voltage monotonically decreased with increasing VOTMS content with a minimum switching voltage of about 15 V with a response time of about 10 ms. However, in the presence of VOTMS, the droplets coalesced and caused random scattering, thus lowering the off-state diffraction efficiency below that of virgin PUA. CONCLUSION: It was found that VOTMS was essential to drive the film. The VOTMS segments of the polymer are preferentially exposed to the polymer/LC interfaces and decrease the surface anchoring strength and also influence the orientation of LC droplets. Also, lower molecular weight bifunctional polypropylene glycol generally gave greater diffraction efficiency, confirming that grating formation is favoured with higher crosslink density due to the greater polymer/LC phase separation.

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