研究目的
Investigating the effects of solvents on the microstructural features of poly(methylhydrosiloxane)/divinylbenzene aerogels.
研究成果
Pore formation in PMHS/DVB polymer aerogels is strongly influenced by solvent solubility and swelling properties, with 'good' solvents (cyclohexane, THF) leading to higher shrinkage, smaller pore sizes, and lower specific surface areas, while 'bad' solvents (acetone, n-hexane) result in more open microstructures. This hypothesis requires additional validation through future experiments.
研究不足
The measurements carry a substantial error margin, and common pore-formation concepts do not fully explain the observed data. Further experiments with solvent mixtures and light scattering are needed for validation.
1：Experimental Design and Method Selection:
The study involves synthesizing PMHS/DVB aerogels via hydrosilylation reaction in highly diluted conditions, using different solvents (n-hexane, cyclohexane, tetrahydrofuran, acetone) to explore their impact on pore formation. The rationale is based on solubility and swelling concepts.
2：Sample Selection and Data Sources:
Samples are prepared with a fixed mass ratio of PMHS to DVB (1:2) in
3：5 g of solvent, using chemicals purchased from suppliers without further purification. List of Experimental Equipment and Materials:
Equipment includes a magnetic stirrer, pressure reactor (Parr acid digestion vessel model 4749), home-made CO2-reactor, N2 physisorption instrument (Micromeritics ASAP 2010), FE-SEM (Zeiss supra 60), and caliper for measurements. Materials include PMHS, DVB, solvents (cyclohexane, acetone, THF, n-hexane), Pt catalyst, and liquid CO
4：Experimental Procedures and Operational Workflow:
Mix PMHS and DVB in solvent, homogenize with stirrer, add Pt catalyst, transfer to pressure reactor, heat at 150°C for 6 h, cool, wash wet gel with solvent, perform solvent exchange with liquid CO2 (10 exchanges at 10°C), supercritical dry at 45°C and 100-110 bar. Characterize with porosimetry and microscopy.
5：Data Analysis Methods:
Specific surface area calculated using BET method, pore volume and average pore size derived from N2 adsorption isotherms, microstructural analysis via FE-SEM images.
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FE-SEM
supra 60
Zeiss
Used for microstructural characterization of aerogel samples.
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Poly(methylhydrosiloxane)
MW~1900, CAS: 63148-57-2
Alfa Aesar
Precursor polymer for aerogel synthesis, bearing Si-H groups for hydrosilylation reaction.
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Divinylbenzene
Technical grade, 80%, CAS: 1321-74-0
Alfa Aesar
Cross-linking agent with C=C groups for hydrosilylation reaction.
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Platinum divinylmethylsiloxane complex
~2% in xylene, CAS: 68478-92-2
Sigma Aldrich
Catalyst for the hydrosilylation reaction.
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Pressure reactor
4749
Parr
Used for heating the reaction mixture at 150°C for cross-linking.
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N2 physisorption instrument
ASAP 2010
Micromeritics
Used for porosity characterization via nitrogen adsorption at -196°C.
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Caliper
Used for measuring linear dimensions of samples to calculate shrinkage and density.
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