Avoiding Cracks in Nanoparticle Films

Prosser, Jacob H.; Brugarolas, Teresa; Lee, Steven; Nolte, Adam J.; Lee, Daeyeon

doi:10.1021/nl302555k

Cited by 135 publications

(108 citation statements)

References 43 publications

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“…It should be mentioned that nanoparticle fi lms are stable against disassembly in the same dispersion medium from which they were deposited. [ 37 ] Detailed studies on the mechanical stability of colloidal assemblies propose that particles are likely to be held together by bridges of water hydrogen bonded to the surface, which act as a cement for the structure. [ 38 ] …”

Section: Microstructural Characteristicsmentioning

confidence: 99%

Selective UV Reflecting Mirrors Based on Nanoparticle Multilayers

Smirnov

Calvo

Míguez

2013

Adv Funct Materials

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A new type of nanostructured selective ultraviolet (UV) reflecting mirror is presented. Periodic porous multilayers with photonic crystal properties are built by spin‐coating‐assisted layer‐by‐layer deposition of colloidal suspensions of nanoparticles of ZrO2 and SiO2 (electronic band gap at λ < 220 nm). These optical filters are designed to block well‐defined wavelength ranges of the UVA, UVB, and UVC regions of the electromagnetic spectrum while preserving transparency in the visible. The shielding against those spectral regions arises exclusively from optical interference phenomena and depends only on the number of stacked layers and the refractive index contrast between them. In addition, it is shown that the accessible pore network of the as‐deposited multilayer allows preparing thin, flexible, self‐standing, transferable, and adaptable selective UV filters by polymer infiltration, without significantly losing reflectance intensity, i.e., preserving the dielectric contrast. These films offer a degree of protection comparable to that of traditional ones, without any foreseeable unwanted secondary effects, such as photodegradation, increase of local temperature or, as is the case for organic absorbers, generation of free radicals, all of which are caused by light absorption.

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Section: Microstructural Characteristicsmentioning

confidence: 99%

Selective UV Reflecting Mirrors Based on Nanoparticle Multilayers

Smirnov

Calvo

Míguez

2013

Adv Funct Materials

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“…Several attempts have been made towards curbing these instabilities, which include usage of soft particles, 10 coating hard particles with soft shells, 17 addition of polymeric plasticizers, 18 or emulsions and sequential deposition of multiple layers. 19 The methods proposed so far have primarily focused on altering the suspension composition or mechanical properties of the gel, 20 the drying modes, 21−23 as well as the drying kinetics. 24 External perturbations in the form of applied low-voltage electric field during drying of laponite gels have shown promising results.…”

Section: Introductionmentioning

confidence: 99%

Effect of Surface Wettability on Crack Dynamics and Morphology of Colloidal Films

et al. 2015

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The effect of surface wettability on the dynamics of crack formation and their characteristics are examined during the drying of aqueous colloidal droplets (1 μL volume) containing nanoparticles (53 nm mean particle diameter, 1 w/w %). Thin colloidal films, formed during drying, rupture as a result of the evaporation-induced capillary pressure and exhibit microscopic cracks. The crack initiation and propagation velocity as well as the number of cracks are experimentally evaluated for substrates of varying wettability and correlated to their wetting nature. Atomic force and scanning electron microscopy are used to examine the region in the proximity of the crack including the particle arrangements near the fracture zone. The altered substrate-particle Derjaguin-Landau-Verwey-Overbeek (DLVO) interactions, as a consequence of the changed wettability, are theoretically evaluated and found to be consistent with the experimental observations. The resistance of the film to cracking is found to depend significantly on the substrate surface energy and quantified by the critical stress intensity factor, evaluated by analyzing images obtained from confocal microscopy. The results indicate the possibility of controlling crack dynamics and morphology by tuning the substrate wettability.

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“…[6][7][8] However, great care must be taken to engineer these surfaces to prevent crack formation, which ultimately leads to device failure. [ 9 ] The desire to prevent crack formation [10][11][12][13] has led to a relatively limited focus on the potential benefi ts of cracks, [ 14,15 ] especially as a useful materials design tool. This proposal-that cracks could facilitate materials design-has at its core the great variety of cracking phenomena that have been observed in granular, [ 16,17 ] polymeric, [ 18,19 ] crystalline, [ 14,20 ] and glassy materials [21][22][23] but have so far not been harnessed towards the controlled functionalization of surfaces.…”

Section: Doi: 101002/adma201306335mentioning

confidence: 99%