UV-induced photolysis of polyurethanes

Petit, Charlotte; Bachmann, Julian; Michalek, Lukas; Catel, Yohann; Blasco, Eva; Blinco, James P.; Unterreiner, Andreas‐Neil; Barner‐Kowollik, Christopher

doi:10.1039/d1cc00124h

Cited by 21 publications

(17 citation statements)

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“…In addition to the exploration of Norrish-type reactions for photoinitiation, the photorelease of preformed polymer blocks and networks via Norrish pathways was also mapped. In two separate studies, , o -nitrobenzyl moieties were explored as potential photolytic units that could be incorporated into polymers to facilitate on-demand degradation. When the o -nitrobenzyl was modified by substituting two alcohol groups (Figure , R8 ) and an action plot was recorded, it was surprisingly found that the peak reactivity was only red-shifted by 10 nm relative to the absorption maximum (λ max = 350 nm) associated with the NO bond.…”

Section: Discussionmentioning

confidence: 99%

“…Molar extinction spectra (solid curves, left axis) and adjusted action plot yields (symbols, right axis) of various photochemical release reactions for photodegradation. For ease of comparison, percentage yields were adapted from the literature ,, and normalized by the number of photoreactive units in solution and the number of photons delivered to the sample to give adjusted % yields. The inset highlights the low-intensity absorption region.…”

Section: Discussionmentioning

confidence: 99%

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Action Plots in Action: In-Depth Insights into Photochemical Reactivity

et al. 2021

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Predicting wavelength-dependent photochemical reactivity is challenging. Herein, we revive the well-established tool of measuring action spectra and adapt the technique to map wavelength-resolved covalent bond formation and cleavage in what we term “photochemical action plots”. Underpinned by tunable lasers, which allow excitation of molecules with near-perfect wavelength precision, the photoinduced reactivity of several reaction classes have been mapped in detail. These include photoinduced cycloadditions and bond formation based on photochemically generated o-quinodimethanes and 1,3-dipoles such as nitrile imines as well as radical photoinitiator cleavage. Organized by reaction class, these data demonstrate that UV/vis spectra fail to act as a predictor for photochemical reactivity at a given wavelength in most of the examined reactions, with the photochemical reactivity being strongly red shifted in comparison to the absorption spectrum. We provide an encompassing perspective of the power of photochemical action plots for bond-forming reactions and their emerging applications in the design of wavelength-selective photoresists and photoresponsive soft-matter materials.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Action Plots in Action: In-Depth Insights into Photochemical Reactivity

et al. 2021

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“…In an exemplary manner, photosensitive o ‐nitrobenzyl moieties were introduced into a polyurethane (in which, the strong urethane linkage and often high degree of crosslinking make them a challenge to degrade without damaging the environment) as structural units. [ 15 ] Those respective light‐responsive units have enabled the polymer to be broken down upon exposure to UV light. Accordingly, this specific approach is postulated to aid the development of polyurethane‐based degradable packaging and adhesives.…”

Section: Green Chemistrymentioning

confidence: 99%

Getting the Terms Right: Green, Sustainable, or Circular Chemistry?

Mutlu

Barner

2022

Macro Chemistry & Physics

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Green chemistry, sustainable chemistry, and circular chemistry are important concepts for the modern lifestyle, current research directions, and worldwide industries. These three concepts are closely related and interconnected but cannot be used synonymously. In addition, they are addressing two different economic models, i.e., linear economy and circular economy. The current contribution focuses on the importance of these decisive chemistries for the development of a sustainable future and their role in the realm of circular economy and the planetary boundaries framework-especially for the planetary boundary of "novel entities." Researchers active in the field of polymer chemistry play an important role as plastic pollution and resource in addition to environmental depletion, caused by the still increasing production of polymers and plastics, become more and more pronounced. It is also reported that multi-and interdisciplinary approaches are needed to develop solutions for a sustainable future.

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“…In 2011, our group introduced, for the first time, a new class of photodegradable polymers based on poly(ketals/acetals), exhibiting main-chain scission at incredibly low irradiation doses (10 mJ cm −2 ) compared to other polymeric materials [ 7 , 8 ]. More recently, Kowollik and co-workers reported the synthesis of main-chain photodegradable polyurethanes by introducing ONB moieties along the backbone of a polyurethane chain, and studied the degradation profiles of these materials both in solution and on thin films using a nanosecond pulsed laser at 340 nm [ 9 ].…”

Section: Introductionmentioning

confidence: 99%

Photo- and Acid-Degradable Polyacylhydrazone–Doxorubicin Conjugates

2021

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Light-mediated polymer degradation has attracted considerable attention in various applications, including photo-patterning, tissue engineering and photo-triggered drug delivery. In this study, we report the synthesis and characterization of a new, linear, main-chain photo- and acid-degradable copolymer based on acylhydrazone linkages. The polymer was synthesized via a step-growth copolymerization of adipic acid dihydrazide with a bifunctional poly(ethylene glycol) bearing benzaldehyde end-groups, under mild acidic conditions, to afford a hydrophilic PEG-alt-adipic acid (PEG-alt-AA) alternating copolymer. The synthesized polymer was characterized by size exclusion chromatography, proton nuclear magnetic resonance and attenuated total reflection-Fourier transform infrared spectroscopies. The main-chain photo- and acid-induced degradation of the copolymer in dimethylsulfoxide and water, respectively, was verified by UV-vis spectroscopy at light intensities as low as 0.1 mW cm−2 at λ = 254 nm. Next, a model anticancer drug, doxorubicin (DOX), was chemically linked to the polymer chain end(s) via acylhydrazone bond(s), resulting in amphiphilic PEG-alt-adipic acid-DOX (PEG-alt-AA-DOX) polymer–drug conjugates. The conjugates were self-assembled in water to form spherical nanoparticles, as evidenced by scanning and transmission electron microscopies. The irradiation of the self-assembled PEG-alt-AA-DOX conjugates with UV light and the decrease of the solution pH resulted in the disruption of the assemblies due to the photolysis and acidolysis of the acylhydrazone bonds, and the release of the therapeutic cargo.

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UV-induced photolysis of polyurethanes

Abstract: Waste production associated with the use of non-degradable materials in packaging is a growing cause of environmental concern, with the polyurethane (PU) class being notorious for their lack of degradability....

Cited by 21 publications

References 29 publications

Action Plots in Action: In-Depth Insights into Photochemical Reactivity

Action Plots in Action: In-Depth Insights into Photochemical Reactivity

Getting the Terms Right: Green, Sustainable, or Circular Chemistry?

Photo- and Acid-Degradable Polyacylhydrazone–Doxorubicin Conjugates

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