The Aero-Sol-Gel Reactor used for synthesis of nano-structured ceramic powders. For PDF Format Paper Down Load:
Chem. of Mat. Paper
JNPR Paper(in press).pdf
For PDF Format Paper Down Load: 10/98 Langmuir Paper on SAXS for Pyrolytic Silica and Titania
Foresight Conference Abstract on Applications of Nanopowders in Elastomer Reinforcement
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Fractals/Nano-Structured Materials: Current Funding Sources, Cabosil Division, Cabot Corporation (100K/year), Armstrong World Industries (20K)
Students: Jingyu Hyeon Lee, PhD CandidateF1: Growth Kinetics and Structure Study of Polymers in a Zirconium Alkoxide System A Singhal, L. M. Toth, M. Harris, M. Hu, G. Beaucage, K. D. Keefer, J. S. Lin, J. L. Look submitted J. Non-Crystalline Solids 1997.
F2: Growth and Structure of Zirconium Hydrous Polymers in Aqueous Solutions, A. Singhal, L. M. Toth, G. Beaucage, J. S. Lin, J. Peterson, submitted to Journal of Colloidal and Interface Science 1997
F3: Aero-Sol-Gel Synthesis of Nanostructured Silica Powders, J. Hyeon-Lee, G. Beaucage, S. E. Pratsinis, Submitted to Chemistry of Materials, 1997.
F4: Processing and Microstructure of Polydimethylsiloxane (PDMS) Modified Silica Xerogels, Guo, L., Beaucage, G, Submitted J. Non-Crystalline Solids 1997
F5: Kinetics of Morphological Development in Elastomer Modified Silica Xerogels, G. Beaucage, L. Guo, J Hyeon-Lee, Rubber Chemistry and Technology submitted 1997
F6: Small Angle X-ray Scattering Investigation of Zeolite-Penetrated Poly (Ethyl Acrylate) Composites, Z. Pu, J. E. Mark, G. Beaucage, S Maaref, H. L. Frisch, J. Polym. Sci., Polym. Phys. Ed., (1996) 34 2657-60.
F7: Morphological Development in PDMS/TEOS Hybrid Materials, J. Hyeon-Lee, L. Guo, G. Beaucage, M. A. Macip-Boulis, A. J. M. Yang, J. Polym. Sci., Polym. Phys. Ed. 34, 3073, (1996).
F8: Pseuto IPN's and IPN's of Zeolite 13 X, H. L. Frisch, Y. Xue, S. Maaref, G Beaucage, Z Pu, J. E. Mark, submitted Macromolecules 1997.
F9: Crystal Structures of Monodisperse Colloidal Silica in Poly (Methyl acrylate) Films, J M Jethmalani, W. T. Ford, G Beaucage, accepted Langmuir, 1997.
F10: Morphology of Poyethylene/Carbon Black Composites, G. Beaucage, S Rane, K. B. Schwartz, M Wartenberg, D. W. Schaefer, G. D. Wignall, G. Long, D Fischer. Submitted Macromolecules 1997
F11: The in-situ generation of silica reinforcement in modified polydimethylsiloxane elastomers, Prabakar, S.; Bates, S. E.; Black, E. P.; Ulibarri, T. A.; Schaefer, D. W.; Beaucage, G.; Assink, R. A., Mater. Res. Soc. Symp. Proc. (1996), 435(Better Ceramics through Chemistry VII: Organic/Inorganic Hybrid Materials), 469-474
F12: Interpenetrating and pseudo-interpenetrating polymer networks of poly(ethyl acrylate) and zeolite 13X, Frisch, H. L.; Maaref, S.; Xue, Y.; Beaucage, G.; Pu, Z.; Mark, J. E., J. Polym. Sci., Part A: Polym. Chem. (1996), 34(4), 673-77.
F13: Structural analysis of silica aerogels, Hua, D. W.; Anderson, J.; Di Gregorio, J.; Smith, D. M.; Beaucage, G., J. Non-Cryst. Solids (1995), 186, 142-8
F14: Multiple size scale structures in silica/siloxane composites studied by small-angle scattering, Beaucage, G.; Schaefer, D. W.; Ulibarri, T.; Black, E., Polym. Mater. Sci. Eng. (1993), 70, 268-9
F15: Multiple size scale structures in silica-siloxane composites studied by small-angle scattering, Beaucage, G.; Ulibarri, T. A.; Black, E. P.; Schaefer, D. W., ACS Symp. Ser. (1995), 585(Hybrid Organic--Inorganic Composites), 97-111.
F16: Sol-gel derived silica/siloxane composite materials: The effect of loading level and catalyst activity on silica domain formation, Black, E. P.; Ulibarri, T. A.; Beaucage, G.; Schaefer, D. W.; Assink, R. A.; Bergstrom, D. F.; Giwa-Agbomeirele, P. A.; Burns, G. T., Polym. Mater. Sci. Eng. (1993), 70, 382-3
F17: Sol-gel-derived silica-siloxane composite materials. Effect of reaction conditions in polymer-rich systems, Black, E. P.; Ulibarri, T. A.; Beaucage, G.; Schaefer, D. W.; Assink, Roger A.; Bergstrom, D. F.; Giwa-Agbomeirele, P. A.; Burns, G. T., ACS Symp. Ser. (1995), 585(Hybrid Organic--Inorganic Composites), 237-46
F18: Pore morphology study of silica aerogels, Hua, D.W.; Anderson, J.; Hereid, S.; Smith, D.M.; Beaucage, G., Mater. Res. Soc. Symp. Proc. (1994), 346(Better Ceramics through Chemistry VI), 985-90
F19: Characterization of Porosity in Ceramic Materials by Small-angle Scattering: Vycor Glass and Silica Aerogel, D. W. Schaefer, G. Beaucage, R. K. Brow, B. J. Olivier, T. Rieker, L. Hrubesh, J. S. Lin, in "Modern Aspects of Small-Angle Scattering", H. Brumberger Editor. pp. 299-305, 1995 Kluwer Academic Publishers, Neatherlands.
F20: Origin of Porosity in Resorcinol-Formaldehyde Aerogels, D. W. Schaefer, R. Pekala, G. Beaucage, J. Non-Cryst. Solids 186 (1995) 142-148.
F21: General Routes to Porous Metal Oxides via Inorganic and Organic Templates, C. Roger, M. J. Hampden-Smith, D. W. Schaefer, J. Sol-Gel Sci. Technol. (1994), B, 67-72.
F22: Structure and Topology of Silica Aerogels During Densification, D. W. Schaefer, B. J. Olivier, C. Ashley, G. Beaucage, D. A. Fischer, J. Non-Cryst. Solids (1994), 172-174 (Pt. 1), 647-55.
F23: A SANS Study of Insitu Filled Polydimethylsiloxane, D. W. Schaefer, T. A. Ulibarri, G. Beaucage, "Sub-Micron Multi-Phase Materials, Ed. R. H. Baney et al., Vol. 274 of Materials Research Society Symposium Proceedings, Materials Research Society, Pittsburgh, PA, p. 85-90 (1992).
F24: Molecular weight dependence of domain structure in silica-siloxane molecular composites, T. A. Ulibarri, D. W. Schaefer, G. Beaucage, B. J. Olivier, R. Assink, Mater. Res. Soc. Symp. Proc. (1992), 274 (Submicron Multiphase Materials) 91-95.
F25: Structure of Combustion Aerosols, D. W. Schaefer, B. J. Olivier, G. Beaucage, A. J. Hurd, J. J. Ivie, C. R. Herd, J. Aerosol Sci., 22, Suppl. 1, S447-50 (1991)
F26: Structure of Arylene-Bridged Polysilsesquioxane Xerogels and Aerogels, Loy, D. A., Schaefer, D. W., Beaucage, G., Shea, K. J., J. Non-Crystalline Solids, 1995.
1) Sandia Efforts: Our work in nano-structured materials began with a post-doc at Sandia National Laboratories under Dale Schaefer, partly associated with John Curro and Al Hurd at Sandia and Doug Smith at UNM. Work at Sandia began with the polymer blends effort described above, but quickly branched into nano-structured, semi-crystalline polymer foams discussed below (PAN and IPS foams), amorphous polymer foams (RF system with the Livermore group), sol-gel ceramic based systems (Hurd's group at Sandia and Smith's group at UNM) as well as in situ based PDMS rubber/silica systems (with Dow Corning). A wide range of expertise existed at Sandia to deal with such morphologies, J. Brinker, J. Martin, A. Hurd, K. Keefer, D. W. Schaefer, D. Loy among others. Mass-fractal systems can be easily distinguished in log-log plots of scattering data by a weak power-law decay in intensity over decades of size which is limited at the large-scale (low-angles) by the overall radius of gyration of the structure, and at a small-scale (high angles) by the substructural radius of gyration. Scattering can be used to directly determine the mass-fractal dimension, the composition and these two main structural sizes, the smaller of which can be used to calculate the specific surface area of the material. Surface scattering from primary particles at high-q can also be used to determine the specific surface area using Porod's Law. In analogy with hydro-carbon polymers the primary particle, of such nano-scale structures, is similar to the persistence unit of a polymer chain. The primary particle of a mass-fractal is typically a 3-d object with a single radius of gyration whereas for polymer coils the persistence unit displays one-dimensional scaling (power-law of -1) between the persistence length and the diameter of a persistence unit [ST1-3, F1-6 and 11-18]. In addition to a 3-d primary particle there are several other main differences between ceramic based mass-fractals and polymer coils which are mostly based on the fact that polymer coils are subject to structural thermal equilibrium whereas ceramic chain aggregates are typically pre-determined in structure by irreversible kinetic growth laws. Some of these growth laws were determined at Dupont in pioneering work by Meakin and Scherer (now at Princeton) among other workers. Our efforts in this area began with structural characterization using combined scattering data from SALS, USAXS, SAXS and XRD. Such wide size-range data (typically 8 to 9 orders in size) displays many regimes of structure. For instance, in colloidal silica based aerogels produced by Smith's group at UNM [F12, 18] we have observed 4 easily distinguished levels of structure in scattering: Primary Particles (100), mass-fractal aggregates (500 ), primary agglomerates (800) and micron scale mass-fractal aggregates of these primary agglomerates. Scattering from such complex structures displays transition regimes which must be described in a unified way in order to fully describe the complicated growth mechanisms involved. One of the main successes at Sandia was the development of new scattering functions which could describe these structural transitions and incorporate the existing scattering laws such as mass-fractal and surface fractal laws into a global description of data over such wide ranges of size [ST1-3].
2) UC efforts: At UC our efforts in this area have focused on the production of low thermal conductivity mass-fractal based polymer modified ceramic insulating materials [F4, 5, 7] and on silica and titania powder systems [F3, and paper in preparation]. Some of the latter work has involved collaboration with PPG, Dow Corning and Sortiris Pratsinis and Jerry Lin's groups at UC. Additionally, we have developed a new approach to the production of extremely high surface area silica and titania powders using a process which involves a combined sol-gel/aerosol reactor [F3]. Cabot is involved in the scale-up of this process for production of silica powders. A number of collaborative efforts are underway involving scattering from sol-gel based systems including zirconia systems [F1, 2], colloidal crystals [F9], and zeolite systems [F6, 8, 12].
3) Carbon/PE composites: Parallel to efforts in inorganic systems we have been working for several years in a collaborative effort with K. Schwartz of Raychem on carbon black/polyethylene composites [F10]. This work is aimed at determining the mechanism behind structural transitions in self-resetting fuse materials through the use of USAXS and SAXS data.
Copyright (c) 1998