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Research in Medical & Engineering Sciences

Enhancing Radical-Mediated Photopylomerization Efficacy and Crosslink Depth: Kinetic Modeling of a Two-Monomer System

Submission: August 10, 2019;Published: August 27, 2019

DOI: 10.31031/RMES.2019.08.000682

ISSN: 2576-8816
Volume8 Issue2


The kinetics and rate equations are derived to analyze the enhanced cross-linking via a two-monomer system, in which the photoinitiator (PI) triplet excited state interacts with monomers, [A] and [B], to form reactive intermediates radicals, which could interact with oxygen, [A],[B], and bimolecular termination. Quasi-steady-state conditions are employed to solve for radicals which are used to find the temporal prpfiles of the monomer efficacy and cosslink depth, as a function of light intensity, exposure time, and concentrations of PI, [A] and [B]. Higher light intensity and radical coupling rate constant lead to faster depletion of PI and oxygen concentration; and faster transient rising efficacy, but a lower steadystate efficacy. Conversion efficacy is an increasing function of the ratio [B]/[A]. In contrast, efficacy is a decreasing function of the reaction rate ratio of oxygen and triplet state, resulted by the stronger oxygen inhibition. Efficacy may be improved by additive enhancer-monomer or extended lifetime of photosensitizer triplet-state or oxygen singlet, in consistent with the measured clinical data. Oxygen inhibition effect may be reduced by the presence of D2O, which extends the lifetime of singlet oxygen. Our analytic formulas provide useful guidance for the scaling laws for further clinical studies.

Keywords: Crosslinking; Photopolymerization; Conversion efficacy; Kinetic modeling; Oxygen inhibition

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