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869 results on '"Klok, Harm-Anton"'

3. Synthesis of Amino Acid‐Based Aromatic Poly(Ester Urea)s Using 4‐Hydroxycinnamic Acid‐Derived Diols.

Author

Tekleab, Ghezae and Klok, Harm‐Anton

Subjects
*MONOMERS, *NATURAL resources, *POLYMERS, *CHEMICAL structure, *THERMAL properties, *GLYCOLS, *LIGNIN structure
Abstract

Amino acid‐based poly(ester urea)s are an attractive class of polymers that are of interest for a variety of biomedical applications. Generally, amino acid‐based poly(ester urea)s are prepared by polymerization of diamines, which are obtained from the corresponding amino acids and aliphatic diols. This article presents an alternative synthetic strategy that uses diamine monomers obtained from aromatic, 4‐hydroxycinnamic acid‐derived diols. A library of structurally related diamine monomers has been prepared by coupling l‐leucine to 4‐hydroxycinnamic acid‐based diols that incorporate alkyl spacers of different lengths. The exploration of 4‐hydroxycinnamic acid as a building block is interesting as it can be obtained from various biological resources, such as for example lignin, and thus provides an opportunity to take advantage of (under‐utilized) bio‐based renewables for the design of new polymer materials. These diamine monomers can be copolymerized in a solvent‐free, one‐pot, two‐step process using dimethyl carbonate as an environmentally sustainable reagent to afford amino acid‐based aromatic poly(ester urea) homo‐ and copolymers with thermal properties that can be tuned by varying the chemical structure of the diamine monomer, or via copolymerization of two different monomers. [ABSTRACT FROM AUTHOR]

Published
2024
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5. Future Directions at the Frontier of Polymer Science and Biology

Author

Lecommandoux, Sébastien, Klok, Harm-Anton, Zhong, Zhiyuan, and Deming, Timothy J

Subjects
Biocompatible Materials, Biopolymers, Congresses as Topic, Nanostructures, Nanotechnology, Chemical Sciences, Biological Sciences, Engineering, Polymers
Published
2019

6. Polymers at the Interface with Biology

Author

Deming, Timothy J, Klok, Harm-Anton, Armes, Steven P, Becker, Matthew L, Champion, Julie A, Chen, Eugene Y-X, Heilshorn, Sarah C, van Hest, Jan CM, Irvine, Darrell J, Johnson, Jeremiah A, Kiessling, Laura L, Maynard, Heather D, de la Cruz, Monica Olvera, Sullivan, Millicent O, Tirrell, Matthew V, Anseth, Kristi S, Lecommandoux, Sebastien, Percec, Simona, Zhong, Zhiyuan, and Albertsson, Ann-Christine

Subjects
Biocompatible Materials, Bioengineering, Nanoparticles, Chemical Sciences, Biological Sciences, Engineering, Polymers
Published
2018

13. Swelling and Degrafting of Poly(3-sulfopropyl methacrylate) Brushes

Author

Sant, Sabrina, Kaur, Kuljeet, and Klok, Harm-Anton

Abstract

Upon exposure to a good solvent, polymer brushes prepared via surface-initiated polymerization can undergo degrafting via cleavage of bonds that anchor the polymer tethers to the underlying substrate. As polymer brushes are often used in a solvent swollen state, this has implications for the longevity of these polymer coatings. Improving the fundamental understanding of this process is thus also of practical importance. It is believed that degrafting is the consequence of tension amplification at the bonds that anchor the polymer grafts, which is driven by swelling of the polymer brush film. Taking advantage of the sensitivity of the swelling behavior of poly(3-sulfopropyl methacrylate) (PSPMA) brushes toward changes in ionic strength, this study has investigated the degrafting behavior of these brushes in aqueous media at different LiCl and NaCl concentrations. The aim of these experiments was to investigate whether the rate constant of the degrafting process was correlated with the swelling ratio of the PSPMA brushes. The experiments show that in aqueous LiCl solutions, the initial rate constant of the degrafting process is correlated with the swelling ratio of the PSPMA brush. This observation represents a first example of the correlation between these two parameters for hydrophilic polymer brushes in aqueous media and supports the idea that degrafting is a mechanochemical process driven by a swelling-induced tension at the polymer–substrate interface.

Published
2024
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16. Pyroelectric Polyelectrolyte Brushes

Author

Wang, Jian, primary, Hu, Fei, additional, Sant, Sabrina, additional, Chu, Kanghyun, additional, Riemer, Lukas, additional, Damjanovic, Dragan, additional, Kilbey, S. Michael, additional, and Klok, Harm‐Anton, additional

Published
2023
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24. Chemical Approaches for the Preparation of Bacteria - Nano/Microparticle Hybrid Systems

Author

Bader, Lisa Patricia Elisabeth, Klok, Harm-Anton, Bader, Lisa Patricia Elisabeth, and Klok, Harm-Anton

Abstract

Bacteria represent a class of living cells that are very attractive carriers for the transport and delivery of nano- and microsized particles. The use of cell-based carriers, such as for example bacteria, may allow to precisely direct nano- or microsized cargo to a desired site, which would greatly enhance the selectivity of drug delivery and allow to mitigate side effects. One key step towards the use of such nano-/microparticle - bacteria hybrids is the immobilization of the cargo on the bacterial cell surface. To fabricate bacteria - nano-/microparticle biohybrid microsystems, a wide range of chemical approaches are available that can be used to immobilize the particle payload on the bacterial cell surface. This article presents an overview of the various covalent and noncovalent chemistries that are available for the preparation of bacteria - nano-/microparticle hybrids. For each of the different chemical approaches, an overview will be presented that lists the bacterial strains that have been modified, the type and size of nanoparticles that have been immobilized, as well as the methods that have been used to characterize the nanoparticle-modified bacteria.

Published
2023
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41. Lignin: A Sustainable Antiviral Coating Material

Author

Boarino, Alice, primary, Wang, Heyun, additional, Olgiati, Francesca, additional, Artusio, Fiora, additional, Özkan, Melis, additional, Bertella, Stefania, additional, Razza, Nicolò, additional, Cagno, Valeria, additional, Luterbacher, Jeremy S., additional, Klok, Harm-Anton, additional, and Stellacci, Francesco, additional

Published
2022
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48. Biodegradation of water-soluble and water-dispersible polymers for agricultural, consumer, and industrial applications-Challenges and opportunities for sustainable materials solutions

Author

Vandermeulen, Guido W. M., Boarino, Alice, Klok, Harm-Anton, Vandermeulen, Guido W. M., Boarino, Alice, and Klok, Harm-Anton

Abstract

The development of more sustainable material solutions is one of the key challenges today. New materials are subject to an overall risk assessment of which their impact on the environment is an important aspect. The biodegradability of a material may support a positive risk assessment. Water-soluble and water-dispersible polymers are widely used in daily life in a very broad range of applications. In anticipation of a further tightening of regulatory requirements and as a consequence of the introduction of sustainability targets in industry, in the next decade or so, industry targets to replace the currently used and predominantly non-biodegradable high value water-soluble and water-dispersible polymers by biodegradable alternatives, wherever sustainably possible. This review provides an overview of the currently used water-soluble and water-dispersible polymers in detergent formulations for home care, in water treatment and in crop protection. These polymers have been engineered to near perfect performance at minimum costs. We address the challenges faced when introducing biodegradable alternatives in existing product value chains, and we highlight opportunities to further improve and fine-tune the biodegradation of these materials. This overview is intended to contribute to the development of novel biodegradable water-soluble and water-dispersible polymers, both at academia and industry.

Published
2022
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