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Computational and Experimental Study of the Effect of PEG in the Preparation of Damascenone-Imprinted Xerogels.
MedLine Citation:
PMID:  23320513     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
Macromolecules such as polyethylene glycol (PEG) have been frequently used in the preparation of xerogels mainly with the purpose of tuning the meso or macroporosity. However, PEG has never been applied in the context of the preparation of molecularly imprinted xerogels for small molecules. Thus we decided to conduct a computational and experimental study of the incorporation of PEG into formerly studied sol-gel mixtures for the preparation of damascenone imprinted xerogels. Computationally, two types of pre-gelification models were studied, one representing the initial mixture (SI3/SIPA:5:3 models) and the other representing the same mixtures after a considerable solvent loss (SI3/SIPA:40:1 models). The latter ones were particularly prolific in providing clear effects of the PEG. In SI3:40:1 model (containing SI3 units - Si3O3(OH)6 - mimicking the final xerogels backbone) a prohibitive instead of a promoting effect of PEG on the template-SI3 association was observed. PEG was found to interpose the SI3 aggregates, turning them smaller and more disperse. In agreement with that, much higher porosity and surface area were found for the corresponding xerogel prepared with PEG, while no appreciable improvement of the imprinting efficiency could be observed. In SIPA:40:1 model (containing both SI3 and SIPA units; SIPA - Si3O3(OH)5C3H6NHC6H5, representing the introduction of the organic functional group into the xerogel network) the interactions related to the network structuring were not significantly affected. This was due to the fact that the SIPA units themselves had a dispersive effect on the silica network, the PEG molecules were "pushed" into the aqueous/methanolic continuum and their presence was somewhat redundant. Accordingly, both prepared SIPA-xerogels (with PEG or not) exhibited higher porosity comparing to SI3-xerogels. Although the simulation results were not conclusive about the effect of PEG on the template-functional group association, experimentally it was clear that the imprinting effect was not improved with PEG.
Authors:
Manuel Azenha; Borys Krzysztof Szefczyk; Dianne Loureiro; Porkodi Kathirvel; Antonio Fernando Silva; M Natalia Dias Soeiro Cordeiro
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2013-1-16
Journal Detail:
Title:  Langmuir : the ACS journal of surfaces and colloids     Volume:  -     ISSN:  1520-5827     ISO Abbreviation:  Langmuir     Publication Date:  2013 Jan 
Date Detail:
Created Date:  2013-1-16     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9882736     Medline TA:  Langmuir     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
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