The influence of N-vinyl-2-pyrrolidinone in polymerization of holographic polymer dispersed liquid crystals (HPDLCs)

White, Timothy J.; Liechty, William B.; Natarajan, Lalgudi V.; Tondiglia, Vincent P.; Bunning, Timothy J.; Guymon, C. Allan

doi:10.1016/j.polymer.2006.01.030

Cited by 47 publications

(34 citation statements)

References 37 publications

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“…Addition of a small molecular weight monomer NVP has been shown to accelerate the gelation of acrylate‐based hydrogels . NVP has also been shown to react preferentially with acrylate double bonds and improves acrylate conversion . The crosslinking of NVP together with PEGDA also yields a co‐polymer network that contains additional poly(NVP) kinetic chains, which impact network structure and mechanical properties.…”

Section: Resultsmentioning

confidence: 99%

Degradable thiol-acrylate hydrogels as tunable matrices for three-dimensional hepatic culture

Hao

Lin

2013

J. Biomed. Mater. Res.

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A degradable poly(ethylene glycol)-diacrylate (PEGDA) hydrogel system was developed using simple macromer formulations and visible light initiated thiol-acrylate photopolymerization. In addition to PEGDA, other components in this gelation system include eosin-Y as a photo-sensitizer, bi-functional thiol (dithiothreitol, DTT) as a dual-purpose co-initiator and cross-linker, and N-vinylpyrrolidone (NVP) as a co-monomer. Gelation was achieved through a mixed-mode step-chain growth polymerization mechanism under bright visible light exposure. Increasing photo-sensitizer or NVP concentrations accelerated photo-crosslinking and increased final gel stiffness. Increasing bi-functional thiol content in the prepolymer solution only increased gel stiffness to some degree. As the concentration of thiol surpassed certain range, thiol-mediated chain-transfer events caused thiol-acrylate gels to form with lower degree of cross-linking. Pendant peptide, such as integrin ligand RGDS, was more effectively immobilized in the network via a thiol-acrylate reaction (using thiol-bearing peptide Ac-CRGDS. Underline indicates cross-linkable motif) than through homo-polymerization of acrylated peptide (e.g., acryl-RGDS). The incorporation of pendant peptide comes with the expense of a lower degree of gel cross-linking, which was rectified by increasing co-monomer NVP content. Without the use of any readily degradable macromer, these visible light initiated mixed-mode cross-linked hydrogels degraded hydrolytically due to the formation of thiol-ether-ester bonds following thiol-acrylate reactions. An exponential growth relationship was identified between the hydrolytic degradation rate and bifunctional thiol content in the prepolymer solution. Finally, we evaluated the cytocompatibility of these mixed-mode cross-linked degradable hydrogels using in situ encapsulation of hepatocellular carcinoma Huh7 cells. Encapsulated Huh7 cells remained alive and proliferated as time to form cell clusters. The addition of NVP at a higher concentration (0.3%) did not affect Huh7 cell viability but resulted in reduction of cell metabolic activity, which was accompanied by an elevated urea secretion from the encapsulated cells.

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Section: Resultsmentioning

confidence: 99%

Degradable thiol-acrylate hydrogels as tunable matrices for three-dimensional hepatic culture

Hao

Lin

2013

J. Biomed. Mater. Res.

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“…NVP enhances diffraction efficiency by decreasing liquid crystal droplet size. White et al performed an exhaustive study about how NVP influences pre-polymer mixture based on DPHPA for holographic purposes [7].…”

Section: Recording Materialsmentioning

confidence: 99%

A dynamic beam splitter using polymer dispersed liquid crystal materials

et al. 2012

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We build a dynamic beam splitter with a holographic optical element (HOE). The laser light goes through the HOE and a fraction of intensity diffracted and transmitted could be tuned by an electric signal. We use holographic polymer dispersed liquid crystals materials. It is made by holographic recording in which the liquid crystal molecules diffuse to dark zones in the diffraction grating and they can be oriented by means of an electric field. The orientation of the liquid crystal produces a refraction index variation which changes the diffraction efficiency and therefore the grating has a dynamic behavior.

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“…White et al reported that the addition of N-vinyl pyrrolidinone delayed LC phase separation and increased the overall polymerisation rate, resulting in reduced LC domain size. [13] Schulte et al considered that, when fluorinated monomer was used in PDLC preparation, phase separation of LCs would be enhanced, and more LC nematic fraction and better EO performance would be obtained. [14] Kim et al investigated the effects of doping a polymer matrix with graphene on the diffusion and grating formation rates, and confirmed that the graphene can broaden the width of LC layer.…”

Section: Introductionmentioning

confidence: 99%

Effect of macro-RAFT agent on the morphology of polymer dispersed liquid crystals

Shao

Zhang

et al. 2014

Liquid Crystals

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In this study, macro-(RAFT) reversible additional fragmental chain transfer agent prepared by reversible additional fragmental chain transfer polymerisation has been incorporated into polymer dispersed liquid crystals (PDLCs). The effects of concentration, molecular weight and glass transition temperature of macro-RAFT agent were studied in terms of morphology, polymerisation kinetics, molecular weight of polymer matrix and electrooptical properties of the films. It was found that the key factor influencing morphology was the mobility of macro-RAFT agent chain rather than polymerisation rate and molecular weight of polymer matrix. Furthermore, the decrease in the mobility of macro-RAFT agent chain caused less liquid crystal nematic fraction, smaller liquid crystal domain size and greater driving voltage.

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The influence of N-vinyl-2-pyrrolidinone in polymerization of holographic polymer dispersed liquid crystals (HPDLCs)

Cited by 47 publications

References 37 publications

Degradable thiol-acrylate hydrogels as tunable matrices for three-dimensional hepatic culture

Degradable thiol-acrylate hydrogels as tunable matrices for three-dimensional hepatic culture

A dynamic beam splitter using polymer dispersed liquid crystal materials

Effect of macro-RAFT agent on the morphology of polymer dispersed liquid crystals

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