Polydicyclopentadiene based aerogel: a new insulation material
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Lightweight polydicyclopentadiene (pDCPD) based aerogels were developed via a simple sol-gel processing and supercritical drying method. The uniform pDCPD wet gels were first prepared at room temperature and atmospheric pressure through ring opening metathesis polymerization (ROMP) incorporating homogeneous ruthenium catalyst complexes (Grubbs catalyst). Gelation kinetics were significantly affected by both catalyst content and target density (i.e., solid content), while gel solvents also played important role in determining the appearance and uniformity of wet gel and aerogel products. A supercritical carbon dioxide (CO2) drying method was used to extract solvent from wet pDCPD gels to afford nanoporous aerogel solid. A variety of pDCPD based aerogels were synthesized by varying target density, catalyst content, and solvent and were compared with their xerogel analogs (obtained by ambient pressure solvent removal) for linear shrinkage and thermal conductivity value (1 atm air, 38 °C mean temperature). Target density played a key role in determining porosity and thermal conductivity of the resultant pDCPD aerogel. Differential scanning calorimetery (DSC) demonstrated that the materials as produced were not fully-crosslinked. The pDCPD based aerogel monoliths demonstrated high porosities, low thermal conductivity values, and inherent hydrophobicity. These aerogel materials are very promising candidates for many thermal and acoustic insulation applications including cryogenic insulation.
KeywordsPolydicyclopentadiene (pDCPD) Aerogels Ring opening metathesis polymerization (ROMP) Supercritical drying Nanoporous Insulation
This work was conducted by the financial support of the United States Defense Advanced Research Projects Agency (DARPA), SBIR Contract No. W31P4Q-05-C-0231. The authors are grateful to Mr. Max Mesham, Ms. Geeta Bhakhari, and Mr. Nathan Bhobho for their helps in preparing samples and also, to Ms. Sara Rosenberg, Dr. Shannon White, and Dr. Jeffrey Boehme for their valuable helps. The authors would like to thank Dr. Karen Wood in DARPA for her continuous supports for this work. The authors are also grateful to Dow Corning Analytical Lab for SEM measurement.
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