Photochemical crosslinking of nylon-6,6 induced by 2-substituted anthraquinones

Allen, Norman S.; Hurley, John P.; Bannister, David; Follows, Gordon W.

doi:10.1016/0014-3057(92)90224-p

Cited by 19 publications

(10 citation statements)

References 3 publications

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“…Photo-excited anthraquinone dyes and textiles share a long history, and the modification of polymers in this fashion has led to both degradation and stabilization of the materials in various cases . For nylon-6,6, Allen and co-workers studied the particular mechanisms of crosslinking (Scheme ) using 1- and 2-substituted anthraquinone derivatives (AQX), discovering that the triplet anthraquinones can both abstract an H atom or oxidize the terminal amine or amide in the polymer backbone. , Both pathways lead to the generation of “macro-alkyl” radicals 45.1 or 45.2 which subsequently undergo cross-linking. Up to 60% cross-linking was observed for some anthraquinones, which were employed in 2 wt %.…”

Section: Benzophenones and Quinonesmentioning

confidence: 99%

Organic Photoredox Catalysis

2016

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In this review, we highlight the use of organic photoredox catalysts in a myriad of synthetic transformations with a range of applications. This overview is arranged by catalyst class where the photophysics and electrochemical characteristics of each is discussed to underscore the differences and advantages to each type of single electron redox agent. We highlight both net reductive and oxidative as well as redox neutral transformations that can be accomplished using purely organic photoredox-active catalysts. An overview of the basic photophysics and electron transfer theory is presented in order to provide a comprehensive guide for employing this class of catalysts in photoredox manifolds.

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Section: Benzophenones and Quinonesmentioning

confidence: 99%

Organic Photoredox Catalysis

2016

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“…This copolymer can be synthesized in high yields by following a straightforward procedure (Figure S1a, Supporting Information). We used this polymer because poly(methyl methacrylate) (PMMA) has attracted significant interest for laboratory-scale rapid prototyping due to its prominence in microfluidics and biochips mostly due to its outstanding optical clarity and good biocompatibility. , AOAQs have been used as dyes and UV photoinitiators since the 1990s . Recently, AOAQ moieties have been studied as a cross-linker for CHic systems as it shows fast photoreaction at low irradiation energy …”

Section: Resultsmentioning

confidence: 99%

Substrate-Independent Maskless Writing of Functionalized Microstructures Using CHic Chemistry and Digital Light Processing

Song

Kotz‐Helmer

Rapp

et al. 2022

ACS Appl. Mater. Interfaces

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Maskless photolithography based on digital light processing (DLP) is an attractive technique for the rapid, flexible, and cost-effective fabrication of complex structures with arbitrary surface profiles on the microscale. In this work, we introduce a new material system for structure formation by DLP that is based on photoreactive polymers for the local and light-induced C,H-insertion cross-linking (CHic). This approach allows a simple and versatile generation of microstructures with a broad spectrum of geometries and chemistries irrespective of the nature of the chosen substrates and thus allows direct writing of surface functionalization patterns with high spatial control. The CHicable prepolymer is first coated on a substrate to form a solvent-free (glassy) film, and then the DLP system patterns the light with arbitrary shape to induce local cross-linking of the prepolymer. Using this method, the desired structures with complex features with a lateral resolution of several microns and a topography of tens of nanometers could be fabricated within 30 s. Furthermore, the universal applicability of the CHic reaction enables the printing on a wide variety of substrates, which greatly broadens the using scenarios of this printing approach.

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“…The latter leads to a (formal) C–H insertion reaction and a covalent connection of the two polymer chains. When a sufficient number of chains become connected, a polymer network is formed. , …”

Section: Resultsmentioning

confidence: 99%

“…When a sufficient number of chains become connected, a polymer network is formed. 12,18 To follow the photocrosslinking process, UV−vis spectra were used to track the amount of photoreactive groups in the polymer. The UV−vis spectrum of PDMAA-co-5% AOAQ showed an absorption maximum at 257 nm and one at 329 nm (Figure 2a).…”

Section: Resultsmentioning

confidence: 99%

“…In a negative photoresist, a thin polymer film becomes insoluble in light-exposed areas, mostly through crosslinking. The most popular negative photoresists are epoxy-based polymers (e.g., SU-8) ,, and off-stoichiometry thiol-enes. , Typical negative photoresists can also contain photoreactive groups such as benzophenone, − thioxanthone, − anthraquinone, − benzoin ether, , and acylphosphine moieties. , Upon irradiation through a mask, a negative photoresist transits from compounds, such as oligomers or (low molecular weight) polymers, to crosslinked polymers which have an infinite molecular weight (i.e., spanning the whole irradiated area). Accordingly, the polymer becomes completely insoluble in all irradiated locations, whereas in the shaded areas under the mask, it remains uncrosslinked and is washed away in a following development step.…”

Section: Introductionmentioning

confidence: 99%

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Kinetics of Photocrosslinking and Surface Attachment of Thick Polymer Films

et al. 2021

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We describe the formation process of surface-attached polymer networks generated through photochemically induced C,H insertion crosslinking (CHic). To achieve surface attachment, light must be able to penetrate all the way to the interface between the film and the substrate to trigger the necessary reactions. Although light penetration is typically a nonissue for thin films below 1 μm, it may become difficult for thicker layers. In this contribution, we show that a critical light dose is needed to ensure full percolation. This critical dose can be derived from Lambert–Beer's law and percolation theory. Both experiments and calculations lead to a model, which is able to predict the percolation points of films as a function of light intensity and film thickness, even for very thick films. The only parameters that need to be determined for this model are the linear absorption coefficient of the polymer, its change with increasing irradiation time due to photobleaching, and the percolation point of a thin film.

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Photochemical crosslinking of nylon-6,6 induced by 2-substituted anthraquinones

Cited by 19 publications

References 3 publications

Organic Photoredox Catalysis

Organic Photoredox Catalysis

Substrate-Independent Maskless Writing of Functionalized Microstructures Using CHic Chemistry and Digital Light Processing

Kinetics of Photocrosslinking and Surface Attachment of Thick Polymer Films

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