Large Scale Structures in Nanocomposite Hydrogels

Loizou, Elena; Butler, Paul; Porcar, Lionel; Kesselman, Ella; Talmon, Yeshayahu; Dundigalla, and Avinash; Schmidt, Gudrun

doi:10.1021/ma047411a

Cited by 97 publications

(132 citation statements)

References 20 publications

(49 reference statements)

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“…24 In solution the adsorbed PEO polymer is strongly attached to the clay and the excess polymer that is not adsorbed is stabilizing the polymer-clay network. 28,29,51 The predominant orientation of CNA platelets in solution is with the flow and with the surface normal along the velocity direction. 52 The orientation of CNA platelets in the dried film is expected to be in the film plane (Fig.…”

Section: Resultsmentioning

confidence: 99%

“…In solution the clay particles can only adsorb a maximum amount of polymer until all the clay surfaces are covered. 51 The polymer and the clay build a network-like structure that is interpenetrated by a sub-network of interconnecting pores containing excess polymer and water. 51 Since the polymer adsorbed clay is completely exfoliated in solution (no peaks in diffraction patterns from solution) this solution-structure must collapse, reorder and re-intercalate into blob-like chains during the film formation process.…”

Section: Resultsmentioning

confidence: 99%

“…Our preliminary results from solutions also showed that the platelets within a polymer-clay network are interconnected over the edge more than over the face. 51 We hypothesize that when the network is stretched, and the solvent evaporates simultaneously, the network collapses, the clay platelets reintercalate and the edge to edge connection in solution may Fig. 4 (a) AFM images from the x-y plane sections of multilayered films for CNA60%-PEO40% and (b) LRD60%-PEO40%, both phase images.…”

Section: Resultsmentioning

confidence: 99%

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Supramolecular structures in nanocomposite multilayered films

Stefanescu

Dundigalla

Ferreiro

et al. 2006

Phys. Chem. Chem. Phys.

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We investigate the multilayered structures of poly(ethylene)oxide/montmorillonite nanocomposite films made from solution. The shear orientation of a polymer-clay network in solution combined with simultaneous solvent evaporation leads to supramolecular multilayer formation in the film. The resulting films have highly ordered structures with sheet-like multilayers on the micrometer length scale. The polymer covered clay platelets were found to orient in interconnected blob-like chains and layers on the nanometer length scale. Inside the blobs, scattering experiments indicate the polymer covered and stacked clay platelets oriented in the plane of the film. The polymer is found to be partially crystalline although this is not visible by optical microscopy. Atomic force microscopy suggests that the excess polymer, which is not directly adsorbed to the clay, is wrapped around the stacked platelets building blobs and the polymer also interconnects the polymer-clay layers. Overall our results suggest the re-intercalation of clay platelets in films made from exfoliated polymer-clay solutions as well as the supramolecular order and hierarchical structuring on the nanometer, via micrometer to the centimeter length scale.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Supramolecular structures in nanocomposite multilayered films

Stefanescu

Dundigalla

Ferreiro

et al. 2006

Phys. Chem. Chem. Phys.

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“…In addition, the results have a good compliance with the measured dynamic modulus of human lateral condyle [51]. Under shear stress, the polymer chains reversibly adsorb and desorb onto the charged silicate surfaces while adopting trains and loops conformations [52,53]; hence, the viscous modulus of the hydrogel composite is enhanced compared to the pristine PEG hydrogels.…”

Section: Mechanical Properties Of Hydrogelsmentioning

confidence: 62%

Injectable polyethylene glycol-laponite composite hydrogels as articular cartilage scaffolds with superior mechanical and rheological properties

Nojoomi

Tamjid

Simchi

et al. 2016

International Journal of Polymeric Materials and Polymeric Biom

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TitleInjectable polyethylene glycol-laponite composite hydrogels as articular cartilage scaffolds with superior mechanical and rheological properties ABSTRACTIn this study, injectable PEG-based hydrogels containing Laponite particles with mechanical and structural properties close to the natural articular cartilage are introduced. The nanocomposites are fabricated by imide ring opening reactions utilizing synthesized copolymers containing PEG blocks and nanoclay through a two-step thermal poly-(amic acid) process. Butane diamine is used as nucleophilic reagent and hydrogels with interconnected pores with sizes in the range of 100-250 µm are prepared. Improved viscoelastic properties compared with the conventional PEG hydrogels are shown. Evaluation of cell viability utilizing human mesenchymal stem cells determines cytocompatibility of the nanocomposite hydrogels. GRAPHICAL ABSTRACT ARTICLE HISTORY

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“…Recent cryo-TEM studies revealed the polymer-clay gels contain structures on multiple length-scales. Direct-imaging cryo-TEM of dilute pure clay solutions showed individual clay platelets, about 1 nm thick [42]. In the polymer-clay gel, characterized by FF, a fine texture of a network-like structure made of interconnected strings, ∼4 nm thick, was observed.…”

Section: Cryo-tem Investigations Of Lmog Gelsmentioning

confidence: 96%

Large Scale Structures in Nanocomposite Hydrogels

Cited by 97 publications

References 20 publications

Supramolecular structures in nanocomposite multilayered films

Supramolecular structures in nanocomposite multilayered films

Injectable polyethylene glycol-laponite composite hydrogels as articular cartilage scaffolds with superior mechanical and rheological properties

Direct-Imaging and Freeze-Fracture Cryo-Transmission Electron Microscopy of Molecular Gels

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