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Nematic - like alignment in SWNT thin films from aqueous colloidal suspensions / Budhadipta Dan in Industrial & engineering chemistry research, Vol. 51 N° 30 (Août 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 30 (Août 2012) . - pp. 10232-10237 Titre : Nematic - like alignment in SWNT thin films from aqueous colloidal suspensions Type de document : texte imprimé Auteurs : Budhadipta Dan, Auteur ; Anson W. K. Ma, Auteur ; Erik H. Haroz, Auteur Année de publication : 2012 Article en page(s) : pp. 10232-10237 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Colloidal  suspension  Thin  film Résumé : We present a modification of the vacuum filtration technique for fabricating transparent conductive SWNT thin films with local nematic-like orientational ordering. Dilute SWNT surfactant dispersions are filtered through a vacuum filtration setup in a slow and controlled fashion. The slow filtration creates a region of high SWNT concentration dose to the filter membrane. While slowly moving through this region, SWNTs interact and align with each other, resulting in the formation of thin films with local nematic ordering. Scanning electron microscopy and image analysis revealed a local scalar order parameter (S2D) of 0.7―0.8 for slow filtration, three times higher than those produced from "fast filtration" (S2D ≈ 0.24). Orientational ordering is demonstrated with different stabilizing surfactants, as well as with dispersions enriched in metallic SWNTs, produced by density-gradient ultracentrifugation. Simple estimates of relative convective versus diffusive transport highlight the main differences between slow versus fast filtration and the resulting SWNT concentration profiles. Comparisons with previous studies on three stages of liquid-crystal phase transition provide insight into the spontaneous ordering process, indicating the lack of a "healing stage", which results in a microstructure consisting of staggered domains in our SWNT films. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=26201440 [article] Nematic - like alignment in SWNT thin films from aqueous colloidal suspensions [texte imprimé] / Budhadipta Dan, Auteur ; Anson W. K. Ma, Auteur ; Erik H. Haroz, Auteur . - 2012 . - pp. 10232-10237. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 30 (Août 2012) . - pp. 10232-10237 Mots-clés : Colloidal  suspension  Thin  film Résumé : We present a modification of the vacuum filtration technique for fabricating transparent conductive SWNT thin films with local nematic-like orientational ordering. Dilute SWNT surfactant dispersions are filtered through a vacuum filtration setup in a slow and controlled fashion. The slow filtration creates a region of high SWNT concentration dose to the filter membrane. While slowly moving through this region, SWNTs interact and align with each other, resulting in the formation of thin films with local nematic ordering. Scanning electron microscopy and image analysis revealed a local scalar order parameter (S2D) of 0.7―0.8 for slow filtration, three times higher than those produced from "fast filtration" (S2D ≈ 0.24). Orientational ordering is demonstrated with different stabilizing surfactants, as well as with dispersions enriched in metallic SWNTs, produced by density-gradient ultracentrifugation. Simple estimates of relative convective versus diffusive transport highlight the main differences between slow versus fast filtration and the resulting SWNT concentration profiles. Comparisons with previous studies on three stages of liquid-crystal phase transition provide insight into the spontaneous ordering process, indicating the lack of a "healing stage", which results in a microstructure consisting of staggered domains in our SWNT films. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=26201440