Behavior of quaternary ammonium salt photobase generators on initiating free radical photo‐polymerization

Zhong, Rong; Yang, Jianwen; Zeng, Zhaohua; Chen, Yonglie

doi:10.1002/pi.1989

Cited by 8 publications

(5 citation statements)

References 22 publications

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“…Previous works proved that tetraphenylborate salts give aromatic fragments including phenyl radicals upon irradiation, and these phenyl radicals can be used for initiating free-radical photopolymerization. [52][53][54] Thus, the improved polymerization kinetics is not only due to the extra effect of the thiol-acrylate Michael addition reaction but also due to the extra radicals produced by the tetraphenylborate salts.…”

Section: Polymerization Kineticsmentioning

confidence: 99%

Thiol–epoxy/thiol–acrylate hybrid materials synthesized by photopolymerization

Sun

et al. 2013

J. Mater. Chem. C

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Thiol-epoxy/thiol-acrylate hybrid networks with systematic variations (100/0, 75/25, 50/50, 25/75, 0/100, w/w) were prepared by free-radical photoinitiator (ITX) and photo-base generator (TBD$HBPh 4 ) induced photopolymerization. The enhanced spectral sensitivity of TBD$HBPh 4 at long wavelengths (320-500 nm) with aid of ITX was capable of in situ generation of a strong base (TBD) to achieve the relatively fast and essentially quantitative thiol-epoxy click reaction. The ITX/TBD$HBPh 4 photoinitiating system, which generated both the free radicals and the strong base upon UV exposure, could induce thiol-epoxy/thiol-acrylate hybrid polymerizations. The kinetics investigated with real-time IR indicated that the thiol-acrylate reactions were faster and more efficient than the thiol-epoxy reactions (>95% conversion in a matter of seconds and minutes, respectively), and the thiol conversion increased with an increase in the epoxy concentration. The incorporation of the thiol-epoxy reaction offered several advantages: the polymerization shrinkage decreased with the increase in the thiolepoxy content due to the low shrinkage factor for the thiol-epoxy system (every mole of epoxy group polymerized produces 6.3 mL of shrinkage). The glass transition temperature of the thiol-epoxy/thiolacrylate hybrid networks progressively increased as a function of the thiol-epoxy content, also resulting in enhanced mechanical and physical properties. This work will be helpful to make optical and electronic devices with low shrinkage and stress, decreased residual monomers, and improved mechanical properties.

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Section: Polymerization Kineticsmentioning

confidence: 99%

Thiol–epoxy/thiol–acrylate hybrid materials synthesized by photopolymerization

Sun

et al. 2013

J. Mater. Chem. C

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“…We then dissolved the NLC‐B1 and NLC‐B2 mixture solutions in methanol solvent (concentration = 3.3 × 10 −6 mol L −1 ), treated it with UV light exposure, and measured the absorption values ( λ max ) over a 0–30 min interval with the use of a UV–Vis absorption spectrometer (VARIAN, Inc., Cary 100 Conc.) to obtain the CP of the LC mixture systems 70, 73–83…”

Section: Methodsmentioning

confidence: 99%

Electro‐optical characteristics in phase separated liquid crystal/photo‐curable acrylic monomer mixture system

Tsai

Lin

et al. 2011

Polymers for Advanced Techs

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One of the main objectives of the experiment was to achieve the vertical aligned (VA) effect. To accomplish this, we employed liquid crystal (LC)/photo-curable acrylic monomers mixture systems to prepare vertical alignment copolymer film (VACOF) for LC molecules with the photo-polymerization induce phase separation (PIPS) process.From previous experimental results, we successfully fabricated LC devices without the micro-protrusion structure. After the application of a saturated voltage, the LC molecules actually exhibited such interesting phenomena as uniaxial orientation, uniform single-domain display state, etc. In this study, to obtain VACOF with smooth surface, we similarly controlled appropriate experimental conditions such as UV light exposure intensity and curing temperature, and altered process parameters such as the cell thickness, chemical structure length of the main chain type biphenol acrylic monomer [to simulate the main chain function of the traditional vertical alignment type polyimide (PI)], etc.During the experiment, we discovered that regardless of the cell thickness, this photo-alignment system would yield the VACOF instead of the polymer disperse liquid crystal (PDLC) film morphology. Another notable finding was that the contrast ratio was heavily influenced by the length of the main chain type acrylic monomer structure for LC/ monomer mixture systems, with enhancement of up to $56%. Therefore, we further investigated the display effects, electro-optical properties, etc. for these two main chain type acrylic monomer systems with different lengths and cell thicknesses.

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“…to obtain the conversion percentage (CP) of the LC mixture system [168][169][170][171][172][173][174][175][176][177][178].…”

Section: Detailed Proceduresmentioning

confidence: 99%

Fabrication of pseudo-pi vertical alignment mode liquid crystal devices with ultra-violet polymerisation and investigations of their electro-optical characteristics

Ho¹,

Lee²

2010

Liquid Crystals

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In this study, we applied the non-contact photo-polymerisation method in fabricating pseudo-polyimide (PI) liquid crystal (LC) devices with vertical alignment copolymer films, in the hope of solving the problems associated with traditional rubbing alignment processes. We mixed different photo-polymerisation-type acrylic monomers and negative dielectric anisotropy LC at proper weight percentages, and induced phase separation behaviour between the photo-polymerisation-type acrylic monomers and the LC molecules in the LC mixture solution through ultraviolet light irradiation, thereby forming copolymer films with vertical alignment effects. We further conducted preliminary characterisation of the alignment mechanism, photo-polymerisation, etc., of the LC molecules and investigated their interactions with alkyl acrylic monomers with different carbon chain lengths (the analogue of alkyl side chains in traditionally used vertical alignment-type PI) and electro-optical properties such as the transmittance, contrast ratio, and response time.

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Behavior of quaternary ammonium salt photobase generators on initiating free radical photo‐polymerization

Cited by 8 publications

References 22 publications

Thiol–epoxy/thiol–acrylate hybrid materials synthesized by photopolymerization

Thiol–epoxy/thiol–acrylate hybrid materials synthesized by photopolymerization

Electro‐optical characteristics in phase separated liquid crystal/photo‐curable acrylic monomer mixture system

Fabrication of pseudo-pi vertical alignment mode liquid crystal devices with ultra-violet polymerisation and investigations of their electro-optical characteristics

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