Kurt Dietliker

Polymerizable Oxime Esters: An Efficient Photoinitiator with Low Migration Ability for 3D Printing to Fabricate Luminescent Devices

ChemPhotoChem, Jul 28, 2020

Supporting information for this article is given via a link at the end of the document.

Download

Photoinitiators for<scp>UV</scp>Inkjet Applications

Water-soluble Photoinitiators: Present and Future

The Royal Society of Chemistry eBooks, Aug 16, 2018

While photopolymerization of water-based formulations is a well-established technology, especiall... more While photopolymerization of water-based formulations is a well-established technology, especially for coating applications, and water-soluble photoinitiators have been known for a long time, they did not find widespread use in industrial applications. Preferentially liquid commercial oil-soluble photoinitiators, possibly in combination with a dispersant aid, can in fact successfully be used in most water-borne UV-curable coatings and inks. Research on new developments aimed at water-soluble photoinitiators was thus mostly restricted to academia. However, in recent years new technologies, such as UV-LED inkjet printing for packaging applications, or the increasingly important additive manufacturing processes in tissue engineering and other biomedical applications, which are based on photolithography of aqueous formulations, created a new need for fully water-soluble photoinitiators that in addition meet requirements such as absorbance in the near-UV–visible, low migration or favorable cytotoxic properties. These requirements, which also created a significant market need, have stimulated significant activity in this field in recent years, not only in academia, but also in industrial, application-focused research. Besides optimization of known concepts aimed at providing water-soluble photoinitiators, several novel approaches have thus been proposed and evaluated, and the introduction of water-soluble photoinitiators as commercial products is close to realization. This chapter gives an overview of recent developments with new water-soluble photoinitiators, but also includes some novel applications of known compounds in aqueous formulations.

Photoinitiators

Wiley-VCH Verlag GmbH & Co. KGaA eBooks, Oct 23, 2017

Industrial applications of photochemistry: automotive coatings and beyond

The Royal Society of Chemistry eBooks, Nov 10, 2010

Photochemistry is an essential tool in both the manufacturing and the use of modern cars. Radiati... more Photochemistry is an essential tool in both the manufacturing and the use of modern cars. Radiation curing is used as a very efficient, economically and ecologically attractive technology for the coating and bonding of many of the parts used in a car, and avoiding degradation of the coating due to photoinduced processes during the foreseen service time is a key issue. Ecological heat management and the OLED technology used for lightening and signage are further examples of useful exploitation of light-induced effects. This paper reviews new photochemistry-related developments such as radiation curing of automotive coatings on the three-dimensional car body, and gives an outlook on future developments.

Mono- and diacylphosphine

Sulfonates d'oximes contenant des groupes réactifs

Alpha-amino acetophenones as new photoinitiators

Compounds of formula I, II, III and IIIa wherein Ar 1 is a radical AROMATICO unsubstituted or sub... more Compounds of formula I, II, III and IIIa wherein Ar 1 is a radical AROMATICO unsubstituted or substituted and at least one of the radicals R1 and R2 are an alkenyl group, cycloalkenyl or arylmethyl, ARE photoinitiators for the polymerization of unsaturated compounds. They are suitable especially for pigmented systems FOTOENURECIMIENTO.

Chapter 13. Water-soluble Photoinitiators: Present and Future

Polymer Chemistry Series, 2018

While photopolymerization of water-based formulations is a well-established technology, especiall... more While photopolymerization of water-based formulations is a well-established technology, especially for coating applications, and water-soluble photoinitiators have been known for a long time, they did not find widespread use in industrial applications. Preferentially liquid commercial oil-soluble photoinitiators, possibly in combination with a dispersant aid, can in fact successfully be used in most water-borne UV-curable coatings and inks. Research on new developments aimed at water-soluble photoinitiators was thus mostly restricted to academia. However, in recent years new technologies, such as UV-LED inkjet printing for packaging applications, or the increasingly important additive manufacturing processes in tissue engineering and other biomedical applications, which are based on photolithography of aqueous formulations, created a new need for fully water-soluble photoinitiators that in addition meet requirements such as absorbance in the near-UV–visible, low migration or favorable cytotoxic properties. These requirements, which also created a significant market need, have stimulated significant activity in this field in recent years, not only in academia, but also in industrial, application-focused research. Besides optimization of known concepts aimed at providing water-soluble photoinitiators, several novel approaches have thus been proposed and evaluated, and the introduction of water-soluble photoinitiators as commercial products is close to realization. This chapter gives an overview of recent developments with new water-soluble photoinitiators, but also includes some novel applications of known compounds in aqueous formulations.

Stimuli-responsive thiol-epoxy networks with photo-switchable bulk and surface properties

RSC Advances, 2018

In the present work, the versatile nature of o-nitrobenzyl chemistry is used to alter bulk and su... more In the present work, the versatile nature of o-nitrobenzyl chemistry is used to alter bulk and surface properties of thiol-epoxy networks. By introducing an irreversibly photocleavable chromophore into the click network, material properties such as wettability, solubility and crosslink density are switched locally by light of a defined wavelength. The synthesis of photo-responsive thiol-epoxy networks follows a photobase-catalyzed nucleophilic ring opening of epoxy monomers with photolabile o-nitrobenzyl ester (o-NBE) groups across multi-functional thiols. To ensure temporal control of the curing reaction, a photolatent base is employed releasing a strong amidine-type base upon light exposure, which acts as an efficient catalyst for the thiol epoxy addition reaction. The spectral sensitivity of the photolatent base is extended to the visible light region by adding a selected photosensitizer to the resin formulation. Thus, in the case of photoactivation of the crosslinking reaction the photorelease of the base does not interfere with the absorbance of the o-NBE groups. Once the network has been formed, the susceptibility of the o-NBE groups towards photocleavage reactions is used for a well-defined network degradation upon UV exposure. Sol-gel analysis evidences the formation of soluble species, which is exploited to inscribe positive tone micropatterns by photolithography. Along with the localized tuning of network structure, the irreversible photoreaction is exploited to change the surface wettability of thiolepoxy networks. The contact angle of water significantly decreases upon UV exposure due to the photoinduced formation of hydrophilic cleavage products enabling the inscription of domains with different surface wettability by photolithography.

Download

ChemInform Abstract: PHOTOREACTIONS. 44. PHOTOCHEMISTRY OF 4-SUBSTITUTED 5-METHYL-3-PHENYLISOXAZOLES

Chemischer Informationsdienst, Dec 14, 1976

In der umfangreichen Arbeit werden Mechanismus und m ögliche Zwischenstufen, insbesondere Benzoni... more In der umfangreichen Arbeit werden Mechanismus und m ögliche Zwischenstufen, insbesondere Benzonitril-methylide, der Photoumlagerung von Isoxazolen wie (I) und (V) untersucht. Die Produkte von (II)-(IV) bzw. (VI) werden isoliert und meist spekroskopisch identifiziert. Teilweise konnten auch Azirine wie (VIII) bei der Photolyse als Zwischenprodukte identifiziert werden. Im Falle stereospezifischer Einsatzprodukte wie (Vd) oder (VII) erfolgt zus ätzlich E-/Z-Isomerisierung. Die Darstellung der Ausgangsverbindungen, eilweise auch die unabh ängige Synthese der Photoprodukte, ist ausf ührlich beschrieben.

Download

Photochemisch induzierte Reaktionen von 3-Amino-2H-azirinen

Helvetica Chimica Acta, Feb 2, 1983

Photochemically Induced Reactions of 3‐Amino‐2H‐azirinesIrradiation of 3‐(N‐methylanilino)‐2H‐azi... more Photochemically Induced Reactions of 3‐Amino‐2H‐azirinesIrradiation of 3‐(N‐methylanilino)‐2H‐azirines with a mercury low pressure lamp induces the cleavage of the C(2), C(3)‐ring bond thus affording nitrilio‐methanide dipols, substituted by an amino group at C(1). Depending on the substitution pattern at C(3), these intermediates can be trapped by dipolarophiles to yield five‐membered heterocycles with high regioselectivity, or they undergo a 1,4‐H‐shift forming 2‐azabutadiene derivatives. Further, the dipol is protonated at C(1) even by weak CH–acids.

Fabrication and Functionalization of 3D Printed Polydimethylsiloxane‐Based Microfluidic Devices Obtained through Digital Light Processing

Advanced materials and technologies, Jul 29, 2020

This work reports the preparation and 3D printing of a custom‐made photopolymer based on acrylate... more This work reports the preparation and 3D printing of a custom‐made photopolymer based on acrylate‐polydimethylsiloxane (PDMS), for the fabrication of complex‐shaped 3D printed microfluidic chips. By selecting and combining the proper materials during the preparation of the resins along with the freedom of design of light‐based 3D printers, 3D microfluidic PDMS‐like chips are obtained with excellent optical features, high chemical stability, and good mechanical properties. Furthermore, taking advantage of unreacted functional groups exposed on the sample's surface after the 3D printing step, the surface properties of the devices are easily and selectively modified during the postcuring step through UV‐induced grafting polymerization techniques, giving an added value to the printed devices in terms of surface treatment compared to conventional methods. The 3D printing of the PDMS‐based resins developed here may potentially transforms the fabrication methodology of PDMS microfluidic devices by decreasing manufacturing costs and time, allowing the production of complex‐shaped and truly 3D microdevices.

Photochemie von in 4-Stellung substituierten 5-Methyl-3-phenyl-isoxazolen.44. Mitteilung über Photoreaktionen

Helvetica Chimica Acta, 1976

ABSTRACT Photochemistry of 4-substituted 5-Methyl-3-phenyl-isoxazoles.4-Trideuterioacetyl-5-methy... more ABSTRACT Photochemistry of 4-substituted 5-Methyl-3-phenyl-isoxazoles.4-Trideuterioacetyl-5-methyl-3-phenyl-isoxazole ([CD3CO]-27), upon irradiation with 254 nm light, was converted into a 1:1 mixture of oxazoles [CD3CO]-35 and [CD3]-35 (Scheme 13). This isomerization is accompagnied by a slower transformation of ([CD3CO]-27) into [CD3]-27.Irradiation of the isoxazole derivatives 28, 29, 30 and (E)-31 yielded only oxazoles 36, 37, 38 and (E), (Z)-39; no 4-acetyl-5-alkoxy-2-phenyl-oxazole, 2-acetyl-3-methyl-5-phenyl-pyrrole or 2-acetyl-4-methoxycarbonyl-3-methyl-5-phenyl-pyrrole, respectively, were formed (Scheme 9 and 10). Similarly (E)-32 gave a mixture of (E), (Z)-40 only (Scheme 11). Upon shorter irradiation, the intermediate 2H-azirines (E), (Z)-41 could be isolated (Scheme 11). Photochemical (E)/(Z)-isomerization of the 2-(trifluoro-ethoxycarbonyl)-1-methyl-vinyl side chain in all the compounds 32, 40 and 41 is fast.At 230° the isoxazoles (E)- and (Z)-32 are converted into oxazoles (E), (Z)-40. The same compounds are also obtained by thermal isomerization of the 2H-azirines (E), (Z)-41.The most probable mechanism for the photochemical transformations of the isoxazoles, as exemplified in the case of the isoxazole 27, is shown in Scheme 13. A benzonitrile-methylide intermediate is postulated for the photochemical conversion of the 2H-azirines into oxazoles. 2H-Azirines are also intermediates in the thermal isoxazole-oxazole rearrangement. It is however not yet clear, if the thermal 2H-azirine-oxazole transformation involves the same transient species as the photochemical reaction.A mechanism for the photochemical isomerization of the 2H-azirine 11 to the oxazole 15 is proposed (Scheme 3).

Light-based 3D printing of functional polydimethylsiloxane- based microfluidic chips

Biomedical science and engineering, Sep 29, 2021

The objective of the work is to fabricate and functionalize 3D printed PDMS-based microfluidic ch... more

Download

Streamlined concept towards spatially resolved photoactivation of dynamic transesterification in vitrimeric polymers by applying thermally stable photolatent bases

Polymer Chemistry, 2022

Photolatent base catalysts exhibiting ideal structural properties for the straightforward manufac... more

Bisacylphosphane and their use as photoinitiators, methods for production of acylphosphanen

ChemInform Abstract: PHOTOREACTIONS. 44. PHOTOCHEMISTRY OF 4‐SUBSTITUTED 5‐METHYL‐3‐PHENYLISOXAZOLES

Chemischer Informationsdienst, 1976

In der umfangreichen Arbeit werden Mechanismus und mögliche Zwischenstufen, insbesondere Benzonit... more

Download

NEW PRODUCT DEVELOPMENT Key to Success of Pigment Producers

Jct Coatingstech, 2007

Uvlight curing is one of the most economical and environmentally compatible curing technologies k... more Uvlight curing is one of the most economical and environmentally compatible curing technologies known. It has successfully enabled numerous industrial applications over recent decades. However, there still remain challenges that prevent penetration into broader areas of interest. For example, there are intrinsic limitations associated with radical photopolymerization, e.g., oxygen inhibition, insufficient curing of shadow areas, poor curing of thick or highly pigmented coatings, lack of adhesion on certain substrates, etc. Recent developments using photolatent additives have specifically targeted these deficiencies and thus support the expansion of the scope of UV curing technology in industrial applications. In addition, novel photo-induced effects have been developed, which open up new application areas that have been unexploited to date.

Oximsufonate and their use as latent sulfonsaüre

Uploads

Papers by Kurt Dietliker

Log In