Spontaneous delamination of affordable natural vermiculite as a high barrier filler for biodegradable food packaging

Dudko, Volodymyr; Timmins, Renee L.; Khoruzhenko, Olena; Röhrl, Maximilian; Greve, Christopher; Rosenfeldt, Sabine; Tammelin, Tekla; Agarwal, Seema; Herzig, Eva M.; Breu, Josef

doi:10.1039/d2ma00734g

Cited by 5 publications

(9 citation statements)

References 68 publications

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“…27 Compared to hydrophobic composites of poly(lactic acid) (PLA) and an organically modified vermiculite (OP: 7.2 cm 3 μm m −2 day −1 bar −1 at 23 °C and 65% rh) or even a hydrophobic 1D crystalline nanocomposite from copolymerization of an organic modifier with a water-insoluble monomer (OP: 0.8 cm 3 μm m −2 day −1 bar −1 at 23 °C and 65% rh) both all-clay coatings perform better. 18,37 In contrast to the results of the OTR, the WVTR measurements of Na-Hec films showed a significant breakdown of the water vapor barrier with increasing rh. For Na- Hec films at 23 °C and 65% rh a WVTR of 3.90 g m −2 day −1 was measured, while at 38 °C and 90% rh WVTR increased to 12.31 g m −2 day −1 .…”

Section: ■ Results and Discussioncontrasting

confidence: 67%

“…), a Na-Hec* processed by slot-die coating, a doctor bladed and copolymerized 1D crystalline nanocomposite of Hec (BisGDA-Hec), and the spray-coated Na-Hec and Gua-Hec. Adapted from refs and with permission from the Royal Society of Chemistry.…”

Section: Resultsmentioning

confidence: 99%

“…6 With regard to the WVP the Na-Hec is outperformed by hydrophobic PLA vermiculite composites (WVP: 423.5 g μm m −2 day −1 atm −1 at 23 °C and 75% rh) while the Gua-Hec is still superior and can compete with 1D crystalline nanocomposites of organically modified hectorite that was copolymerized with a hydrophobic monomer (WVP: 95.5 g μm m −2 day −1 atm −1 at 23 °C and 90% rh). 18,37 For some packaging applications, appealing optical properties are required. While SiO x coatings are statistically isotropic and therefore transparent, an all-clay film consisting of individual micrometer-sized nanosheets might be affected by scattering.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

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Spraying Transparent Nanoglass Coatings for Food Packaging

Schuchardt,

Röhrl,

Federer

et al. 2023

ACS Appl. Nano Mater.

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When coating suspensions of large aspect ratio clay monolayers upon drying, the individual nanosheets self-assemble into thin nanoglass coatings due to the large overlapping areas between restacked clay nanosheets. By exchanging the films with flat-lying, hydrophobic organocations, swelling at higher relative humidity is suppressed, and the interlayer space collapses to less than 3 Å, a value smaller than the kinetic diameter of oxygen. Consequently, diffusion along the interlayer space is impeded, resulting in very good gas barriers. The guanidinium-exchanged all-clay coating was found to have transmission rates for oxygen as low as 0.32 cm3 μm m–2 day–1 atm–1 and for water vapor as low as 3.74 g m–2 day–1, both values determined at harsh conditions (38 °C and 90% relative humidity). The barrier is rather insensitive to swelling with water vapor, and the performance of the waterborne coatings is competitive, in both barrier performance and transparency with vapor-deposited coatings rendering them an alternative for challenging food packaging applications.

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Section: ■ Results and Discussioncontrasting

confidence: 67%

Section: Resultsmentioning

confidence: 99%

Section: ■ Results and Discussionmentioning

confidence: 99%

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Spraying Transparent Nanoglass Coatings for Food Packaging

Schuchardt,

Röhrl,

Federer

et al. 2023

ACS Appl. Nano Mater.

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“…Recently we have shown that selected organocations allow for spontaneous dela-mination, allowing the extension of Bragg type barrier films to more hydrophobic matrices. 18,19 Please note that crystalline films of polycationic polymers with polyanionic clay nanosheets are not directly accessible via mixing them in solution as heterocoagulation will be triggered leading to a disordered precipitate.…”

Section: Introductionmentioning

confidence: 99%

Fabrication of Bragg stack films of clay nanosheets and polycations via co-polymerization of intercalated monomers and functional interlayer cations

Schuchardt

Rosenfeldt

Kalo³

et al. 2023

Nanoscale

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“…As the bonding in layered materials is highly anisotropic, the dissolution is restricted to the stacking direction of the charged layers and therefore has been labeled “1-dimensional (1D) dissolution” in a recent review . Among other, antimony phosphate, 2:1 type clay minerals, − ilerite, or lepidocrocite type titanates , and layered perovskites are members of this spontaneously delaminating group of layered materials.…”

Section: Introductionmentioning

confidence: 99%

Gentle, Spontaneous Delamination of Layered Titanate Yielding New Types of Lithium Titanate Nanosheets

Cha,

Weiß,

Thanner

et al. 2023

Chem. Mater.

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Lepidocrocite-type layered titanate (K 0.8 Ti 1.73 Li 0.27 O 4 ) typically is delaminated in a two-step process, where first K + is exchanged for protons (H 1.07 Ti 1.73 O 4 •H 2 O) followed by deprotonation of the solid acid by tetraalkylammonium hydroxide upon which delamination sets in producing titanate nanosheets. Unfortunately, the harsh acidic conditions during proton exchange concomitantly leach all structural lithium and the obtained nanosheets (Ti 0.87 O 2 0.52− ) suffer from substantial structural defects. Here, we propose a one-step delamination of the pristine K-titanate, where the K + is directly exchanged by a bulky, hydrophilic organocation (N-methyl-D-glucammonium, Meg + ) that spontaneously delaminates in deionized water into titanate nanosheets without any significant loss of structural lithium. The new procedure not only saves one conversion step but also preserves the structural lithium, and moreover, the delamination itself seems to be gentler as indicated by larger aspect ratios of the resulting nanosheets obtained. Starting with the same pristine K-titanate, the established two-step delamination applying tetrabutylammonium hydroxide gave a d 50 diameter of 3 μm, while direct delamination applying Meg + yielded a substantially higher d 50 diameter of 19 μm. The Meg + delamination thus yields lithium titanate nanosheets of high aspect ratio of ≈20,000 in a high yield of ≈99% establishing the suggested procedure to be a highly attractive alternative to the established protocol, while giving access to hitherto unknown types of titanate nanosheets, in which pristine structural lithium ions are preserved.

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Spontaneous delamination of affordable natural vermiculite as a high barrier filler for biodegradable food packaging

Abstract: Expensive biodegradable packaging as a preventative measure against continued accumulation of plastic waste in our environment is often in conflict with the need for high performing packaging materials that prevent...

Cited by 5 publications

References 68 publications

Spraying Transparent Nanoglass Coatings for Food Packaging

Spraying Transparent Nanoglass Coatings for Food Packaging

Fabrication of Bragg stack films of clay nanosheets and polycations via co-polymerization of intercalated monomers and functional interlayer cations

Gentle, Spontaneous Delamination of Layered Titanate Yielding New Types of Lithium Titanate Nanosheets

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