Rehfeldt, Florian

[["dc.bibliographiccitation.firstpage","4294"],["dc.bibliographiccitation.issue","3"],["dc.bibliographiccitation.journal","ACS Sustainable Chemistry & Engineering"],["dc.bibliographiccitation.lastpage","4301"],["dc.bibliographiccitation.volume","6"],["dc.contributor.author","Huang, Heqin"],["dc.contributor.author","Wang, Xiaojie"],["dc.contributor.author","Rehfeldt, Florian"],["dc.contributor.author","Zhang, Kai"],["dc.date.accessioned","2020-05-18T10:10:36Z"],["dc.date.available","2020-05-18T10:10:36Z"],["dc.date.issued","2018"],["dc.description.abstract","Biological tissues are often highly and multiply heterogeneous in both structure and composition, but the integrity of multiheterogeneity in artificial materials is still a big challenge. Herein, dually heterogeneous hydrogels were constructed with two distinct strategies via dynamic bonds and supramolecular cross-links. The hydrogels showed discontinuous spatial ruptures, and the mechanical behaviors of hydrogels could be tuned. The primary heterogeneity resulted from a nonuniform distribution of dynamic and/or static cross-links. The presence of only primary heterogeneity within hydrogels led to uneven mechanical properties that were represented by discontinuous spatial ruptures during the stretching the hydrogel and therefore caused the necking deformation. Further introduction of the secondary heterogeneity by incorporating anisotropic cellulose nanocrystals (CNC) into the hydrogels allowed the adjustment of the necking phenomenon. Moreover, distinct CNC with diverse surface functionalities exhibited different effects: the “active” CNC with surface-attached dynamic bonds retarded the necking propagation, while the “neutral” CNC without further surface modification promoted the extension of necking points. Thus, the regulation of deformation and fracture mode of hydrogels was achieved by the synergy of dually heterogeneous structure."],["dc.identifier.doi","10.1021/acssuschemeng.7b04738"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/65514"],["dc.language.iso","en"],["dc.title","Dually Heterogeneous Hydrogels via Dynamic and Supramolecular Cross-Links Tuning Discontinuous Spatial Ruptures"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.artnumber","1600810"],["dc.bibliographiccitation.issue","12"],["dc.bibliographiccitation.journal","Macromolecular Rapid Communications"],["dc.bibliographiccitation.volume","38"],["dc.contributor.author","Huang, Heqin"],["dc.contributor.author","Wang, Y."],["dc.contributor.author","Wang, X."],["dc.contributor.author","Rehfeldt, Florian"],["dc.contributor.author","Zhang, Kai"],["dc.date.accessioned","2018-11-07T10:22:58Z"],["dc.date.accessioned","2020-05-18T08:18:54Z"],["dc.date.available","2018-11-07T10:22:58Z"],["dc.date.available","2020-05-18T08:18:54Z"],["dc.date.issued","2017"],["dc.description.abstract","A kind of novel heterogeneous composite hydrogel with dynamic nanocrosslinkers is designed, which is built via the preorganized host-guest interaction on the surface of cellulose nanocrystals. The reversible beta-cyclodextrin/adamantane conjunctions and their gradual dissociation on the nanocrystal-polymer interface guarantee the compressibility and stretchability of the composite hydrogels. While the sacrificed toughening mechanism can be rebuilt in the as-prepared hydrogels, it fails to be regenerated in the swollen hydrogels. This fact is originally due to the extreme mechanical contrast between rigid nanocrystals and the flexible polymer phase. This heterogeneity is largely amplified by the swelling process: poly-mer chains are prestretched between nanocrosslinkers and generate residual stress on the dynamic nanocrystalpoly-mer interface. Thus, this swelling-induced heterogeneity resists the reassociation of the sacrificed beta-cyclodextrin/adamantane complexes. Furthermore, the unstable nanocrystalpolymer interface induces the crack propagate along the nanocrosslinker surface, which remarkably retards the crack propagation during the stretch."],["dc.identifier.doi","10.1002/marc.201600810"],["dc.identifier.isi","000403816200001"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/42372"],["dc.language.iso","en"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","PUB_WoS_Import"],["dc.relation.eissn","1022-1336"],["dc.relation.issn","1521-3927"],["dc.title","Robust Heterogeneous Hydrogels with Dynamic Nanocrystal-Polymer Interface"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.artnumber","1970046"],["dc.bibliographiccitation.issue","19"],["dc.bibliographiccitation.journal","Macromolecular Rapid Communications"],["dc.bibliographiccitation.volume","40"],["dc.contributor.author","Huang, Heqin"],["dc.contributor.author","Chen, Yang"],["dc.contributor.author","Wang, Xiaojie"],["dc.contributor.author","Rehfeldt, Florian"],["dc.contributor.author","Zhang, Kai"],["dc.date.accessioned","2020-04-27T08:52:14Z"],["dc.date.available","2020-04-27T08:52:14Z"],["dc.date.issued","2019"],["dc.description.abstract","Front Cover: Manipulation of water transportation within hydrogels is challenging. In article number 1900317, Kai Zhang and co‐workers construct a novel nanocomposite hydrogel with a dually electrostatically crosslinked network that shows thermoresponsive water transportation. The dense microstructure within the hydrogels delays water transportation and is favorable in preserving water. Interestingly, the water absorption, distribution, and dehydration processes can be continuously controlled by tuning the surrounding temperature."],["dc.identifier.doi","10.1002/marc.201970046"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/64357"],["dc.language.iso","en"],["dc.relation.eissn","1521-3927"],["dc.relation.issn","1022-1336"],["dc.title","Thermoresponsive Water Transportation in Dually Electrostatically Crosslinked Nanocomposite Hydrogels"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","117655"],["dc.bibliographiccitation.journal","Carbohydrate Polymers"],["dc.bibliographiccitation.volume","258"],["dc.contributor.author","Pang, Bo"],["dc.contributor.author","Liu, Huan"],["dc.contributor.author","Rehfeldt, Florian"],["dc.contributor.author","Zhang, Kai"],["dc.date.accessioned","2021-06-01T10:49:28Z"],["dc.date.available","2021-06-01T10:49:28Z"],["dc.date.issued","2021"],["dc.identifier.doi","10.1016/j.carbpol.2021.117655"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/86302"],["dc.language.iso","en"],["dc.notes.intern","DOI-Import GROB-425"],["dc.relation.issn","0144-8617"],["dc.title","High internal phase Pickering emulsions stabilized by dialdehyde amylopectin/chitosan complex nanoparticles"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.artnumber","1800562"],["dc.bibliographiccitation.issue","6"],["dc.bibliographiccitation.journal","Macromolecular Chemistry and Physics"],["dc.bibliographiccitation.volume","220"],["dc.contributor.author","Wang, Xiaojie"],["dc.contributor.author","Huang, Heqin"],["dc.contributor.author","Liu, Huan"],["dc.contributor.author","Rehfeldt, Florian"],["dc.contributor.author","Wang, Xiaohui"],["dc.contributor.author","Zhang, Kai"],["dc.date.accessioned","2020-05-18T08:16:05Z"],["dc.date.available","2020-05-18T08:16:05Z"],["dc.date.issued","2019"],["dc.description.abstract","Multi‐responsive hydrogel actuators show promising applications for soft robotics, biomedical engineering, and artificial muscles, but the uncontrollable nature of their motions poses a barrier to practical applications. Herein, a novel type of bilayer hydrogel actuators (BHAs) is presented comprising of a poly(N‐isopropylacrylamide) (PNIPAm) and a poly (N‐hydroxyethyl acrylamide) (PHEAm) hydrogel layer with various compositions, which demonstrate thermal‐responsive and novel solvent‐responsive actuation under water or within solvents. These BHAs exhibit a wide range of regulable bidirectional motions due to the simultaneous co‐nonsolvency property of PNIPAm and the shrinking behavior of PHEAm in ethanol/water mixtures with various ethanol contents. By adjusting the compositions of ethanol/water mixtures, the bending directions and amplitudes of BHAs are precisely regulable and the curvatures of actuators are tunable between −0.34 and 0.3. Because of the temperature‐responsive character of PNIPAm, BHAs fulfilled thermal‐driven motions to lift items. By reinforcing PHEAm layers with cellulose nanocrystals (CNCs) or CNCs bearing methacylamide moieties on the surface, the weight‐lifting capability of BHAs is highly improved to 18 times the weight of their own polymer weights. This design concept with bilayer structures provides a new strategy for the construction of precisely regulable hydrogel actuators, which allows using solvents to exactly control their motions."],["dc.identifier.doi","10.1002/macp.201800562"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/65471"],["dc.language.iso","en"],["dc.title","Multi‐Responsive Bilayer Hydrogel Actuators with Programmable and Precisely Tunable Motions"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.artnumber","e1900317"],["dc.bibliographiccitation.issue","19"],["dc.bibliographiccitation.journal","Macromolecular Rapid Communications"],["dc.bibliographiccitation.volume","40"],["dc.contributor.author","Huang, Heqin"],["dc.contributor.author","Wang, Xiaojie"],["dc.contributor.author","Rehfeldt, Florian"],["dc.contributor.author","Zhang, Kai"],["dc.contributor.author","Yang, Yang"],["dc.date.accessioned","2020-05-18T08:17:56Z"],["dc.date.available","2020-05-18T08:17:56Z"],["dc.date.issued","2019"],["dc.description.abstract","Controlling water transportation within hydrogels makes hydrogels attractive for diverse applications, but it is still a very challenging task. Herein, a novel type of dually electrostatically crosslinked nanocomposite hydrogel showing thermoresponsive water absorption, distribution, and dehydration processes are developed. The nanocomposite hydrogels are stabilized via electrostatic interactions between negatively charged poly(acrylic acid) and positively charged layered double hydroxide (LDH) nanosheets as well as poly(3-acrylamidopropyltrimethylammonium chloride). Both LDH nanosheets as crosslinkers and the surrounding temperatures played pivotal roles in tuning the water transportation within these nanocomposite hydrogels. By changing the surrounding temperature from 60 to 4 °C, these hydrogels showed widely adjustable swelling times between 2 and 45 days, while the dehydration process lasted between 7 and 27 days. A swift temperature decrease, for example, from 60 to 25 °C, generated supersaturation within these nanocomposite hydrogels, which further retarded the water transportation and distribution in hydrogel networks. Benefiting from modified water transportation and rapidly alternating water uptake capability during temperature change, pre-loaded compounds can be used to track and visualize these processes within nanocomposite hydrogels. At the same time, the discharge of water and loaded compounds from the interior of hydrogels demonstrates a thermoresponsive sustained release process."],["dc.description.sponsorship","German Research Foundation http://dx.doi.org/10.13039/501100001659"],["dc.description.sponsorship","Fonds der Chemischen Industrie"],["dc.description.sponsorship","China Scholarship Council http://dx.doi.org/10.13039/501100004543"],["dc.description.sponsorship","Niedersächsische Ministerium für Wissenschaft und Kultur http://dx.doi.org/10.13039/100011937"],["dc.identifier.doi","10.1002/marc.201900317"],["dc.identifier.pmid","31433104"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/65485"],["dc.language.iso","en"],["dc.notes.intern","DeepGreen Import"],["dc.relation.eissn","1521-3927"],["dc.rights","This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited."],["dc.title","Thermoresponsive Water Transportation in Dually Electrostatically Crosslinked Nanocomposite Hydrogels"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","3867"],["dc.bibliographiccitation.issue","4"],["dc.bibliographiccitation.journal","ACS Nano"],["dc.bibliographiccitation.lastpage","3874"],["dc.bibliographiccitation.volume","13"],["dc.contributor.author","Huang, Heqin"],["dc.contributor.author","Wang, Xiaojie"],["dc.contributor.author","Yu, Jinchao"],["dc.contributor.author","Chen, Ye"],["dc.contributor.author","Ji, Hong"],["dc.contributor.author","Zhang, Yumei"],["dc.contributor.author","Rehfeldt, Florian"],["dc.contributor.author","Wang, Yonggui"],["dc.contributor.author","Zhang, Kai"],["dc.date.accessioned","2020-05-18T09:58:37Z"],["dc.date.available","2020-05-18T09:58:37Z"],["dc.date.issued","2019"],["dc.description.abstract","Liquid-solid transition is a widely used strategy to shape polymeric materials and encode their microstructures. However, it is still challenging to fully exploit liquid behaviors of material precursors. In particular, the dynamic and static liquid behaviors naturally conflict with each other, which makes it difficult to integrate their advantages in the same materials. Here, by utilizing a shear-thinning phenomenon in the dynamic hybrid hydrogels, we achieve a hydrodynamic alignment of cellulose nanocrystals (CNC) and preserve it in the relaxed hydrogel networks due to the much faster relaxation of polymer networks (within 500 s) than CNC after the unloading of external force. During the following drying process, the surface tension of hydrogels further enhances the orientation index of CNC up to 0.872 in confined geometry, and these anisotropic microstructures demonstrate highly tunable birefringence (up to 0.004 14). Due to the presence of the boundaries of dynamic hydrogels, diverse xerogels including fibers, films, and even complex three-dimensional structures with variable anisotropic microstructures can be fabricated without any external molds."],["dc.identifier.doi","10.1021/acsnano.9b00551"],["dc.identifier.pmid","30811180"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/65501"],["dc.language.iso","en"],["dc.relation.eissn","1936-086X"],["dc.title","Liquid-Behaviors-Assisted Fabrication of Multidimensional Birefringent Materials from Dynamic Hybrid Hydrogels"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","7371"],["dc.bibliographiccitation.issue","19"],["dc.bibliographiccitation.journal","ACS Sustainable Chemistry & Engineering"],["dc.bibliographiccitation.lastpage","7379"],["dc.bibliographiccitation.volume","8"],["dc.contributor.author","Pang, Bo"],["dc.contributor.author","Zhang, Hua"],["dc.contributor.author","Schilling, Martin Karl"],["dc.contributor.author","Liu, Huan"],["dc.contributor.author","Wang, Xiaojie"],["dc.contributor.author","Rehfeldt, Florian"],["dc.contributor.author","Zhang, Kai"],["dc.date.accessioned","2020-05-18T08:16:46Z"],["dc.date.available","2020-05-18T08:16:46Z"],["dc.date.issued","2020"],["dc.description.abstract","Developing green and sustainable micro/nanoparticles that can be used to stabilize high-internal-phase Pickering emulsions (HIPPEs) via simple methods is of great significance. Herein, polymeric nanoparticles, fabricated via a facile one-step interfacial Schiff base reaction between dialdehyde cellulose (DAC) and aniline, were successfully used to stabilize oil-in-water HIPPEs. The ratio between aldehyde groups in DAC and aniline demonstrated a great effect on the emulsifying performance of the resultant dialdehyde cellulose-aniline nanoparticles (DANPs). DANPs prepared with suitable high ratios of aldehyde groups to aniline (from 20:1 to 6:1) were able to stabilize oil-in-water HIPPEs with various oil types, such as toluene, hexadecane, styrene, and even viscous edible sunflower oil. In comparison, DANPs fabricated with the ratios of aldehyde groups in DAC to aniline of 4:1 and lower were unable to stabilize HIPPEs. In addition, HIPPEs stabilized by DANPs prepared with higher ratios of aldehyde groups to aniline have smaller droplets, higher storage modulus, and better thermal stability. In particular, DANP-stabilized HIPPEs had good stability at diverse environmental conditions, e.g., higher temperatures (of up to 80 °C) and higher electrolyte concentrations (of at least 50 mM NaCl). Although phase separation occurred to all DANP-stabilized HIPPEs after a freeze–thaw treatment, gel-like HIPPEs could be easily refabricated by handshaking, for at least five cycles of the freeze–thaw treatment. In addition, macroporous poly(melamine-formaldehyde) (PMF) foams were prepared using DANP-stabilized HIPPEs as a template. Therefore, this study further advances the design of stable HIPPEs using polysaccharide-based nanoparticles and the potential of HIPPEs in practical applications."],["dc.identifier.doi","10.1021/acssuschemeng.0c01116"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/65476"],["dc.language.iso","en"],["dc.title","High-Internal-Phase Pickering Emulsions Stabilized by Polymeric Dialdehyde Cellulose-Based Nanoparticles"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dspace.entity.type","Publication"]]