Supramolecular Stimuli‐Responsive Microgels Crosslinked by Tannic Acid

López, Catalina Molano; Pich, Andrij

doi:10.1002/marc.201700808

Cited by 40 publications

(46 citation statements)

References 39 publications

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“…TA is a widely available natural occurring polyphenol that is employed in the food and medicine industries because of its antioxidant and astringent properties. − The high acidity of the phenolic hydroxyl group makes it a particularly good hydrogen donor and this feature has been exploited as a noncovalent cross-linker of natural and synthetic polymers. − Here, we demonstrate that TA can be used to enhance the stiffness of films cast from waterborne polymers. First, we detail the synthesis of a series of latexes containing H-bond accepting monomers.…”

Section: Introductionmentioning

confidence: 79%

Hydrogen Bond-Directed Formation of Stiff Polymer Films Using Naturally Occurring Polyphenols

2019

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Although coatings cast from waterborne polymer dispersions are significantly more environmentally friendly than their solvent-based counterparts, their relatively poor mechanical properties limit their use. In this work, mechanically reinforced polymer films from waterborne dispersions are presented in which the stiffness is provided by the hydrogen bond-directed formation of a honeycomb microstructure. Blends of an acrylic copolymer latex containing a hydrogen bond accepting pyrrolidone group and tannic acid, a naturally occurring H-bond donating polyphenol, lead to a cellular structure with physically crosslinked tannic acid forming the cell walls and the acrylic polymer occupying the space inside the cell walls. It is demonstrated that the formation of the honeycomb microstructure was promoted by H-bond interactions and led to materials with greater mechanical performance. Furthermore, we show that the high strength of the phenol−amide interaction allows these mechanical properties to be retained even after extensive exposure to water. This approach opens the way to replacement of solventborne polymers in many applications that require hard polymer films.

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Section: Introductionmentioning

confidence: 79%

Hydrogen Bond-Directed Formation of Stiff Polymer Films Using Naturally Occurring Polyphenols

2019

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“…[ 1 ] They are widely used for applications in, e.g., drug delivery, cell encapsulation, or separation and purification technologies. [ 2 , 3 , 4 , 5 ] Poly( N ‐isopropylacrylamide) (PNIPAAm) and poly( N ‐vinylcaprolactam) (PVCL) are the two most popular temperature‐responsive polymers used for μgel preparation. [ 5 ] While the use of PNIPAAm is limited in biomedical applications due to its toxicity, [ 6 ] PVCL μgels have been shown to be biocompatible retaining the advantageous temperature‐responsive properties of PNIPAAm.…”

Section: Introductionmentioning

confidence: 99%

“…[ 9 , 10 , 11 ] The number, spatial distribution, and chemical identity of the crosslinkers connecting the functional main chains control these parameters. While PNIPAAm μgels can be obtained by self‐crosslinking during dispersion polymerization, [ 12 ] it is necessary to use covalent crosslinkers [ 13 , 14 ] or supramolecular motifs [ 3 ] for the construction of PVCL μgels.…”

Section: Introductionmentioning

confidence: 99%

Mechanically Resistant Poly(N‐vinylcaprolactam) Microgels with Sacrificial Supramolecular Catechin Hydrogen Bonds

et al. 2022

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Microgels (μgels) swiftly undergo structural and functional degradation when they are exposed to shear forces, which potentially limit their applicability in, e.g., biomedicine and engineering. Here, poly( N ‐vinylcaprolactam) μgels that resist mechanical disruption through supramolecular hydrogen bonds provided by (+)‐catechin hydrate (+C) are synthesized. When +C is added to the microgel structure, an increased resistance against shear force exerted by ultrasonication is observed compared to μgels crosslinked by covalent bonds. While covalently crosslinked μgels degrade already after a few seconds, it is found that μgels having both supramolecular interchain interactions and covalent crosslinks show the highest mechanical durability. By the incorporation of optical force probes, it is found that the covalent bonds of the μgels are not stressed beyond their scission threshold and mechanical energy is dissipated by the force‐induced reversible dissociation of the sacrificial +C bonds for at least 20 min of ultrasonication. Additionally, +C renders the μgels pH‐sensitive and introduces multiresponsivity. The μgels are extensively characterized using Fourier‐transform infrared, Raman and quantitative nuclear magnetic resonance spectroscopy, dynamic light scattering, and cryogenic transmission electron microscopy. These results may serve as blueprint for the preparation of many mechanically durable μgels.

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“…By virtue of these features, natural polyphenols can serve as versatile platforms for material engineering and surface functionalization ( Xu L. Q. et al, 2018 ). In particular, they can be efficiently utilized to link linear polymers together to build crosslinked polymeric materials ( Niu et al, 2020 ), especially high-strength hydrogels ( Xu R. et al, 2018 ; Fan et al, 2018 ; López and Pich, 2018 ; Jiménez et al, 2019 ), and can be recognized as a class of ideal natural and green crosslinkers. However, polyphenols haven’t been utilized as crosslinkers for the construction of elastomers, especially silicone elastomers.…”

Section: Introductionmentioning

confidence: 99%

Tannic Acid as a Natural Crosslinker for Catalyst-Free Silicone Elastomers From Hydrogen Bonding to Covalent Bonding

et al. 2021

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The construction of silicone elastomers crosslinked by a natural crosslinker under a catalyst-free method is highly desirable. Herein we present catalyst-free silicone elastomers (SEs) by simply introducing tannic acid (TA) as a natural crosslinker when using poly (aminopropylmethylsiloxane-co-dimethylsiloxane) (PAPMS) as the base polymer. The crosslinked bonding of these SEs can be easily changed from hydrogen bonding to covalent bonding by altering the curing reaction from room temperature to heating condition. The formability and mechanical properties of the SEs can be tuned by altering various factors, including processing technique, the amount of TA and aminopropyl-terminated polydimethylsiloxane, the molecular weight and -NH2 content of PAPMS, and the amount of reinforcing filler. The hydrogen bonding was proved by the reversible crosslinking of the elastomers, which can be gradually dissolved in tetrahydrofuran and re-formed after removing the solvent. The covalent bonding was proved by a model reaction of catechol and n-decylamine and occurred through a combination of hydroxylamine reaction and Michael addition reaction. These elastomers exhibit good thermal stability and excellent hydrophobic property and can bond iron sheets to hold the weight of 500 g, indicating their promising as adhesives. These results reveal that TA as a natural product is a suitable “green” crosslinker for the construction of catalyst-free silicone elastomers by a simple crosslinking strategy. Under this strategy, TA and more natural polyphenols could be certainly utilized as crosslinkers to fabricate more organic elastomers by selecting amine-containing polymers and further explore their extensive applications in adhesives, sealants, insulators, sensors, and so forth.

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Supramolecular Stimuli‐Responsive Microgels Crosslinked by Tannic Acid

Cited by 40 publications

References 39 publications

Hydrogen Bond-Directed Formation of Stiff Polymer Films Using Naturally Occurring Polyphenols

Hydrogen Bond-Directed Formation of Stiff Polymer Films Using Naturally Occurring Polyphenols

Mechanically Resistant Poly(N‐vinylcaprolactam) Microgels with Sacrificial Supramolecular Catechin Hydrogen Bonds

Tannic Acid as a Natural Crosslinker for Catalyst-Free Silicone Elastomers From Hydrogen Bonding to Covalent Bonding

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