Nanocomposite Hydrogels: A Unique Organic–Inorganic Network Structure with Extraordinary Mechanical, Optical, and Swelling/De-swelling Properties

Haraguchi, Kazutoshi; Takehisa, Toru

doi:10.1002/1521-4095(20020816)14:16<1120::aid-adma1120>3.0.co;2-9

Cited by 1,960 publications

(1,646 citation statements)

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“…Similar to bulk MMT/polymer hydrogels, clay nanoplatelets can be considered as large 'crosslinkers' , and a smaller number of crosslinks may be required to stabilize nanocomposite hydrogel structures compared with all-polymer hydrogels. 4 At the same time, unlike bulk hydrogels, MMT/PAA LbL films are prepared via sequential adsorption from MMT and PAA solutions on a solid; therefore, their structure and composition are governed by different (that is, adsorption) laws than those applicable to their bulk counterparts.…”

Section: Responsive Nanocomposite Assembliesmentioning

confidence: 99%

“…3 Reports on responsive hydrophilic nanocomposites are rare, and those few known to us advantageously use the complementary properties of temperature/pH-responsive polymers and clay nanosheets to yield environmentally controlled free-standing materials. 4 A promising way to leverage the favorable properties of hydrophilic-responsive nanocomposites on surfaces is to use the layer-by-layer (LbL) technique to construct 'smart' surface coatings. 5 To construct clay-containing LbL films, electrostatic interactions of positively charged polymers with negatively charged basal planes of silicate nanosheets, 6,7 neutral polymer/nanoplatelet hydrogen bonding 8 or a combination of the two have been explored.…”

Section: Introductionmentioning

confidence: 99%

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Small-molecule-hosting nanocomposite films with multiple bacteria-triggered responses

et al. 2014

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We report pH/bacteria-responsive nanocomposite coatings with multiple mechanisms of antibacterial protection that include the permanent retention of antimicrobials, bacteria-triggered release of antibiotics and bacteria-induced film swelling. A novel small-molecule-hosting film was constructed using layer-by-layer deposition of montmorillonite (MMT) clay nanoplatelets and polyacrylic acid (PAA) components, both of which carry a negative charge at neutral pH. The films were highly swollen in water, and they exhibited major changes in swelling as a function of pH. Under physiologic conditions (pH 7.5, 0.2 M NaCl), hydrogel-like MMT/PAA films took up and sequestered B45% of the dry film matrix mass of the antibiotic gentamicin, causing dramatic film deswelling. Gentamicin remained sequestrated within the films for months under physiologic conditions and therefore did not contribute to the development of antibiotic resistance. When challenged with bacteria (Staphylococcus aureus, Staphylococcus epidermidis or Escherichia coli), the coatings released PAA-bound gentamicin because of bacteria-induced acidification of the immediate environment, whereas gentamicin adsorbed to MMT nanoplatelets remained bound within the coating, affording sustained antibacterial protection. Moreover, an increase in film swelling after gentamicin release further hindered bacterial adhesion. These multiple bacteria-triggered responses, together with nontoxicity to tissue cells, make these coatings promising candidates for protecting biomaterial implants and devices against bacterial colonization. INTRODUCTIONPolymer nanocomposites uniquely combine the properties of inorganic and organic components that is central to the development of novel advanced materials. The naturally occurring smectite clays, which are chemically and thermally stable and biocompatible, are attractive nanocomposites. Exfoliated clay nanoplatelets strongly impact the mechanical, transport, optical, fire retardant and gas barrier properties of nanocomposite materials. 1,2 For many biomedical applications, however, hydrophilic rather than hydrophobic nanocomposites are of great interest, and responsive properties are essential. 3 Reports on responsive hydrophilic nanocomposites are rare, and those few known to us advantageously use the complementary properties of temperature/pH-responsive polymers and clay nanosheets to yield environmentally controlled free-standing materials. 4 A promising way to leverage the favorable properties of hydrophilic-responsive nanocomposites on surfaces is to use the layer-by-layer (LbL) technique to construct 'smart' surface coatings. 5 To construct clay-containing LbL films, electrostatic interactions of positively charged polymers with negatively charged basal planes of silicate nanosheets, 6,7 neutral polymer/nanoplatelet hydrogen bonding 8 or a combination of the two have been explored. 9

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Section: Responsive Nanocomposite Assembliesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Small-molecule-hosting nanocomposite films with multiple bacteria-triggered responses

et al. 2014

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“…66 NC gels can be simply prepared by mixing synthetic clay (Laponite) and PNIPA monomer in water and allowing them to polymerize with ammonium persulfate. 71,72 The mechanical properties can be easily chosen by the composition.…”

Section: High-performance Polymer Gelsmentioning

confidence: 99%

Small-angle neutron scattering on polymer gels: phase behavior, inhomogeneities and deformation mechanisms

Shibayama

2010

Polym J

202

139

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Recent developments in small-angle neutron scattering (SANS) investigations on polymer gels are reviewed by encompassing (i) volume phase transition and microphase separation, (ii) inhomogeneities in polymer gels, (iii) pressure dependence of hydrophobic interaction and (iv) structural characterization of super-tough gels. These developments owe much to the understanding of gel inhomogeneities and advances in the precision analyses of SANS, such as the contrast variation method coupled with singular value decomposition and the accurate evaluation of incoherent scattering intensity. As one of the fruitful outcomes, deformation mechanisms in various types of super-tough gels are elucidated.

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“…One of the most successful instances of incorporation of colloidal particles into gels is the so-called nanocomposite gel containing organic polymer/inorganic particle networks. 25,26 Nanocomposite gels prepared by polymerization of N-isopropyl acrylamide in the presence of inorganic clay particles showed several striking properties, including drawability up to 1400% of their original lengths and excellent mechanical properties (tensile strength 4300 kPa). The incorporation of cellulose or chitin nanowhiskers was expected to yield similarly effective reinforcement of gels.…”

Section: Introductionmentioning

confidence: 99%

Chitin-chitosan nanocomposite gels: reinforcement of chitosan hydrogels with rod-like chitin nanowhiskers

Araki

Yamanaka

Ohkawa

2012

Polym J

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Nanocomposite gels containing chitosan as a network polymer and chitin nanowhiskers as reinforcing fillers were prepared by cross-linking with the blocked isocyanate hexamethylene-1,6-di-(aminocarboxysulfonate) (HDS). Young's modulus and stress at break of the nanocomposite gels increased to maximum values of 169 and 135 kPa, respectively, with increase in whisker content up to 13.3%, whereas the degree of swelling decreased from 357 to 33.0.

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Nanocomposite Hydrogels: A Unique Organic–Inorganic Network Structure with Extraordinary Mechanical, Optical, and Swelling/De-swelling Properties

Cited by 1,960 publications

References 3 publications

Small-molecule-hosting nanocomposite films with multiple bacteria-triggered responses

Small-molecule-hosting nanocomposite films with multiple bacteria-triggered responses

Small-angle neutron scattering on polymer gels: phase behavior, inhomogeneities and deformation mechanisms

Chitin-chitosan nanocomposite gels: reinforcement of chitosan hydrogels with rod-like chitin nanowhiskers

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