Architecture with photopolymerization

Neckers, Douglas C.

doi:10.1002/pen.760322007

Cited by 14 publications

(8 citation statements)

References 36 publications

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“…These polymerization reactions proceed rapidly at room temperature with a variety of radical-producing photoinitiator systems [13], with the formation of the polymer product temporally controlled by choice of wavelength, intensity and exposure time [14], and spatially controlled by using photomasks [9,15], optics [16,17], or local concentration gradients of initiators [18e21]. However, a critical issue precluding exploitation of the full potential of radical polymerization reactions is oxygen inhibition [20,22e25].…”

Section: Introductionmentioning

confidence: 99%

A quantitative analysis of peroxy-mediated cyclic regeneration of eosin under oxygen-rich photopolymerization conditions

Wong

Kaastrup

Aguirre‐Soto

et al. 2015

Polymer

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a b s t r a c tEosin, a photoreducible xanthene, reacts with tertiary amines and initiates the free radical photopolymerization of aqueous solutions of acrylate monomers. This reaction proceeds even in the presence of a large excess (~1000Â) of inhibiting oxygen via a mechanism that has not been established conclusively. This chemistry has proven useful in the area of biosensing, where the formation of a hydrogel on the time scale of seconds serves as a macroscopic, amplified signal that can be connected to molecular recognition events. In this work, we built a kinetic model to quantitatively explore a mechanism in which eosin is regenerated through the reaction of eosin-based radicals with peroxy-radicals formed from oxygen-inhibition reactions. To determine whether the predictions of this model are consistent with conversion profiles measured using real-time FTIR, we refrained from fitting rate constants or other unknown parameters associated with individual steps in the mechanism to the conversion profile. Rather, we considered physical upper bounds and performed sensitivity analyses spanning several orders of magnitude to predict the reactivity of the system. We explored the effects of the peroxymediated regeneration rate constant, k regen , and the initial eosin concentration on the irradiation time that is required to reach a C]C bond conversion of 0.2 (t 0.2 ). At this C]C bond conversion, the aqueous monomer solutions studied herein have become hydrogels. The predictions of the model capture several trends that we have observed experimentally. However, even when the rate constants associated with eosin regeneration via reaction with peroxy-species are set at the physical upper bounds, the values of t 0.2 predicted by the model are much larger than those that we observed experimentally. The results presented herein motivate and provide a framework for future work to more fully elucidate the mechanism of this interesting and useful photopolymerization reaction.

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Section: Introductionmentioning

confidence: 99%

A quantitative analysis of peroxy-mediated cyclic regeneration of eosin under oxygen-rich photopolymerization conditions

Wong

Kaastrup

Aguirre‐Soto

et al. 2015

Polymer

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“…These characteristics, including the ability to cure rapidly at ambient conditions 2,3 and with intimate control in both time and space when and where the polymerization occurs, [4][5][6] have enabled photopolymerizations to be implemented in a wide range of applications that are as diverse as dental materials, 2,7-10 contact and other lenses, [11][12][13] coatings, [14][15][16][17] photolithography, 4,18-20 microfluidic device fabrication, 4,5,[21][22][23][24] tissue engineering matrices, [25][26][27] and 3D prototyping. 28,29 Unfortunately, despite the vast potential for energy efficient, solvent-free reactions that are able to be performed rapidly at ambient conditions, the range of applica-tions where photopolymerizations are utilized is limited by a general lack of understanding of the polymerization process itself as well as a lack of solutions for persistent problems associated with volume shrinkage and stress, 9,[30][31][32][33] oxygen inhibition, 1,[34][35][36][37][38] and the presence of unreacted, potentially extractable monomer. 34,[39][40][41] For the last 15 years, our group has sought to develop enhanced understanding, including both experimental and modeling approaches, of these reactions while simultaneously utilizing that understanding to address the problems that limit the implementation of photopolymerizations.…”

Section: Introductionmentioning

confidence: 99%

Toward an enhanced understanding and implementation of photopolymerization reactions

2008

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in Wiley InterScience (www.interscience.wiley.com).Photopolymerization reactions proceed rapidly at ambient conditions and are able to exhibit both temporal and spatial control, nevertheless their full potential has been limited by a lack of understanding of the polymerization kinetics and polymer network evolution as well as a lack of custom, functional monomers, and polymerization mechanisms. For the last 15 years, our group has sought to address these limitations by reaction engineering at both the fundamental and applied levels with a focus on increasing the understanding, potential, and implementation of photopolymerization reactions. In particular, we have modeled and experimentally validated the complex spatially dependent polymerization kinetics and network heterogeneity, and we have implemented these systems for applications improvement or development in lithography, microdevice fabrication, biomaterials, biodetection, dental materials, and surface coatings.An illustration of typical photopolymerization kinetic behavior is presented in Figure 2a, where the polymerization rate is plotted as a function of the double bond conversion for two different photoinitiation rates. Two polymerization regimes are clearly identifiable in each curve and are typical Here, the chain length dependence is most prominent at the early stages of the reaction, during autoacceleration and is largely absent at the higher conversions where reaction diffusion controlled termination dominates the termination reaction process. Figure adapted from ref. 80.

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“…In addition, the polymerization of monomers with low ceiling temperatures (e.g., α‐methylstyrene) or polymerization in the presence of temperature‐sensitive situations (e.g., in biomedical and dental applications) are made possible. Photopolymerization has been used in a wide range of applications including dentistry, contact and other lenses, coatings, photolithography, tissue engineering matrices, and 3D prototyping . However, there are problems related to volume shrinkage and stress, oxygen inhibition, and the presence of unreacted monomer which can limit the utilization of this method .…”

Section: Introductionmentioning

confidence: 99%