Posts Tagged ‘amine’

Dental Photoinitiators

Friday, March 8th, 2013
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Simply described, photoinitiators are chemicals that generate radicals upon exposure to light.  A more complete description would include all the complexities inherent with the chemical nature of photoinitiators including type, concentration and absorptivity.  All of these factors must be taken into consideration when optimizing a light-curable formulation.

With PL Industries, the new division of Esstech Inc., we can now provide the monomers, adhesion promoters, oligomers, photoinitiators and technical expertise to guide you in your material selection.  The following is an example of our photoinitiator products.

 

PL-CQ
Camphorquinone
Absorption Range:  400-550 nm, 470 nm peak

Description:  Type II, fine yellow powder, very common and effective for dental restoratives, heat aids in dissolution

PL-TPO
2,4,6-Trimethylbenzoyl-diphenylphosphine oxide
Absorption Range: 230-430 nm, 385 nm peak

Description:  Type I, off-white, crystalline powder, dissolves in most monomers, exhibits photo-bleaching properties

PL-PPD
1-Phenyl 1,2-propanedione (PPD)
Absorption Range:  300-480 nm, 393 nm peak

Description:  Type II, yellow liquid, believed to have a lower rate of polymerization that is not detrimental to overall conversion

PL-EDB
Ethyl-4-dimethylamino benzoate
(EDAB, EDMAB)

Description:  a tertiary amine synergist typically used in combination with type II photoinitiators such as PL-CQ

X-866-0000
Dihydroxyethyl-para-toluidine
(DHEPT)

Description:  solid, off-white amine co-initiator that is low in color, requires melting or crushing to simplify incorporation

X-867-0000
2-dimethylaminoethyl methacrylate
(DMAEMA, MADAME)

Description:  a clear, colorless liquid used as an amine synergist for type II photoinitiators, commonly used in 1:2 ratio with CQ

Contact Us to request samples and more information at techsupport@esstechinc.com .

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Camphorquinone Decomposition Rates Vary Among UDMA and BisGMA/TEGDMA Formulations

Thursday, March 18th, 2010
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Photobleaching of camphorquinone during polymerization of dimethacrylate-based resins

Silvana Asmusen, Gustavo Arenas, Wayne D. Cook, Claudia Vallo

Dental Materials, December 2009 (Vol. 25, Issue 12, Pages 1603-1611)

Abstract: Objective: The aim of this study was to compare the photobleaching rate of CQ in different dental resins. Methods: The photodecomposition rate of CQ/amine system in bis-GMA/TEGDMA, bis-EMA and UDMA polymerizing monomers was evaluated at different light intensities. The photobleaching of the CQ was studied by monitoring the decrease in light absorption as a function of continuous irradiation time. The absorption changes were assessed by recording the transmitted light that passed through samples of monomers containing CQ/amine. Results: Complete photobleaching of CQ was observed in all the monomer tested and the rate constant for the photobleaching was proportional to the radiation intensity. Hydrogen abstraction from amines by the excited CQ state via electron transfer and direct hydrogen abstraction from monomer structures were involved in the CQ photoreduction. CQ was photobleached in the absence of coinitiator in a dimethacrylate monomer containing a carbamate functional group (UDMA). This behavior was attributed to the presence of labile hydrogen atoms in the UDMA monomer. The CQ photobleaching rate constant in UDMA containing CQ/amine was similar to that in UDMA in the absence of amine. Moreover, the efficiency of CQ to photoinitiate the polymerization of UDMA in the absence of amine demonstrated that the radicals derived from the UDMA monomer via hydrogen abstraction are highly reactive toward double bonds.

Significance: CQ photoinitiates the polymerization of the UDMA monomer in the absence of amine and the efficiency of this process is comparable to that of traditional bis-GMA and bis-EMA monomers activated with CQ/amine.

Link:  http://www.demajournal.com/article/S0109-5641(09)00285-1/abstract


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