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Title: | Influence of Structure-Directing Additives on the Properties of Poly(methylsilsesquioxane) Aerogel-Like Materials | Authors: | Ochoa, Marta Lamy-Mendes, Alyne Maia, Ana Portugal, António Durães, Luisa |
Keywords: | silica aerogel-like materials; ambient pressure drying; structure-directing additives; glycerol; poly(ethylene glycol) | Issue Date: | 28-Jan-2019 | Publisher: | MDPI | Project: | This work was developed under the project “AerTPS—Aerogel Thermal Protection Systems” by the Consortium “Active Space Technologies/Faculdade de Ciências e Tecnologia da Universidade de Coimbra/Instituto Pedro Nunes (AST/FCTUC/IPN)”, funded by QREN, under the Operational Programme for Competitiveness Factors granted by the European Regional Development Fund. Alyne Lamy-Mendes acknowledges CNPq (Brazil) for the funding of the PhD fellowship project 234184/2014-0/GDE, under the programme “Ciência sem Fronteiras”. The authors also acknowledge the support of the CIEPQPF research unit (Coimbra), funded by FEDER funds through the Operational Programme for Competitiveness Factors—COMPETE and National Funds, through FCT—Foundation for Science and Technology, under the projects POCI-01-0145-FEDER-006910 and UID/EQU/00102/2013 | Serial title, monograph or event: | Gels | Volume: | 5 | Issue: | 1 | Abstract: | The effect of glycerol (GLY) and poly(ethylene glycol) (PEG) additives on the properties of silica aerogel-like monoliths obtained from methyltrimethoxysilane (MTMS) precursor was assessed. The tested molar ratios of additive/precursor were from 0 to 0.1 and the lowest bulk densities were obtained with a ratio of 0.025. When a washing step was performed in the sample containing the optimum PEG ratio, the bulk density could be reduced even further. The analysis of the material's microstructure allowed us to conclude that GLY, if added in an optimum amount, originates a narrower pore size distribution with a higher volume of mesopores and specific surface area. The PEG additive played a binder effect, leading to the filling of micropores and the appearance of large pores (macropores), which caused a reduction in the specific surface area. The reduction of the bulk density and the microstructural changes in the aerogels induced by adding a small amount of these additives confirm the possibility of fine control of properties of these lightweight materials. The achieved high porosity (97%) and low thermal conductivity (~35 mW·m-1·K-1) makes them suitable to be used as thermal insulators. | URI: | https://hdl.handle.net/10316/107002 | ISSN: | 2310-2861 | DOI: | 10.3390/gels5010006 | Rights: | openAccess |
Appears in Collections: | I&D CIEPQPF - Artigos em Revistas Internacionais |
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