Please use this identifier to cite or link to this item:
Title: Polymeric aerogels
Authors: Longo, Simona
Guerra, Gaetano
Guerra, Gaetano
Proto, Antonio
Daniel, Christophe
Di Renzo, Francesco
Reverchon, Ernesto
Keywords: Crystalline phase
Issue Date: 7-Mar-2014
Publisher: Universita degli studi di Salerno
Abstract: Aerogels are a unique class of materials characterized by a highly porous network, being attractive for many applications such as thermal and acoustic insulation, capacitors or catalysis. In more recent years, polymeric aerogels based on thermoplastic uncrosslinked polymers, where the knots of the three-dimensional networks are physical, not formed by covalent chemical bonds but by small crystallites, have been obtained. These physically cross-linked aerogels are generally prepared by supercritical CO2 extraction of thermoreversible organogels. Besides aerogels, another class of porous materials, which has received attention in the last decade by the scientific community, is constituted by semicrystalline thermoplastic polymers whose crystalline phase is nanoporous, i.e. presents a density lower than the corresponding amorphous phase. In this thesis monolithic aerogels, where the crystallites that constitute the physical knots exhibit a nanoporous-crystalline form have been prepared for polymer that exhibit a nanoporous crystalline phase e.g. syndiotactic polystyrene (s-PS) and poly(2,6-dimethyl-1,4-phenylene)oxide (PPO).[2c] Physically cross-linked aerogels have also been prepared for poly(2,6-diphenyl-1,4-phenylene oxide) (PPPO), that does not exhibit a nanoporous crystalline phase, but a highly absorbent amorphous phase.[2d] Moreover the preparation of aerogels of polyethylene, is described. The fast kinetics and high sorption capacity of VOCs by aerogels, as well as their good handling characteristics, make these new materials particularly suitable as a sorption medium to remove selectively traces of pollutants from water and air. Furthermore nanocomposites aerogels, with large amounts of both intercalated and exfoliated organically modified montmorillonite (OMMT) and including the nanoporous-crystalline δ form of s-PS, were prepared. Also for high OMMT content, the aerogel preparation procedures occur without re-aggregation of the exfoliated clay, which is instead observed for other kinds of polymer processing. Analogous aerogels were prepared with graphene oxide (GO) leading to complete GO exfoliation as well as its substantial reduction. The most important result is that the aerogel preparation allows the inclusion of also large amount of nanofillers, without aggregation, at least up to a content of 20 wt%. This allows to improve mechanical and electrical properties of the nanoporous-crystalline aerogels of s-PS. Composite aerogels exhibiting large nanofiller content, can be also used as masterbatches for polymer composites. [edited by author]
Description: 2012 - 2013
Appears in Collections:Chimica

Files in This Item:
File Description SizeFormat 
tesi_S_Longo.pdftesi di dottorato3,86 MBAdobe PDFView/Open
tesi_presentazione_ppt_S_Longo.pdftesi di dottorato - presentazione tesi in PowerPoint 9,1 MBAdobe PDFView/Open
abstract_in_inglese_S_Longo.pdfabstract in inglese a cura dell'autore304,94 kBAdobe PDFView/Open

Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.