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Thermodynamic Approach to Boron Nitride Nanotube Solubility and DispersionInadequate dispersion of nanomaterials is a critical issue that significantly limits the potential properties of nanocomposites and when overcome, will enable further enhancement of material properties. The most common methods used to improve dispersion include surface functionalization, surfactants, polymer wrapping, and sonication. Although these approaches have proven effective, they often achieve dispersion by altering the surface or structure of the nanomaterial and ultimately, their intrinsic properties. Co-solvents are commonly utilized in the polymer, paint, and art conservation industries to selectively dissolve materials. These co-solvents are utilized based on thermodynamic interaction parameters and are chosen so that the original materials are not affected. The same concept was applied to enhance the dispersion of boron nitride nanotubes (BNNTs) to facilitate the fabrication of BNNT nanocomposites. Of the solvents tested, dimethylacetamide (DMAc) exhibited the most stable, uniform dispersion of BNNTs, followed by N,N-dimethylformamide (DMF), acetone, and N-methyl-2-pyrrolidone (NMP). Utilizing the known Hansen solubility parameters of these solvents in comparison to the BNNT dispersion state, a region of good solubility was proposed. This solubility region was used to identify co-solvent systems that led to improved BNNT dispersion in poor solvents such as toluene, hexane, and ethanol. Incorporating the data from the co-solvent studies further refined the proposed solubility region. From this region, the Hansen solubility parameters for BNNTs are thought to lie at the midpoint of the solubility sphere: 16.8, 10.7, and 9.0 MPa(exp 1/2) for delta d, delta p, and delta h, respectively, with a calculated Hildebrand parameter of 21.8 MPa)exp 1/2).
Document ID
20170000691
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Tiano, A. L. (National Inst. of Aerospace Hampton, VA, United States)
Gibbons, L. (National Inst. of Aerospace Hampton, VA, United States)
Tsui, M. (California Univ. Berkeley, CA, United States)
Applin, S. I. (National Inst. of Aerospace Hampton, VA, United States)
Silva, R. (Texas Univ. Brownsville, TX, United States)
Park, C. (NASA Langley Research Center Hampton, VA, United States)
Fay, C. C. (NASA Langley Research Center Hampton, VA, United States)
Date Acquired
January 20, 2017
Publication Date
January 1, 2016
Publication Information
Publication: Nanoscale
Volume: 8
Issue: 7
Subject Category
Nonmetallic Materials
Report/Patent Number
NF1676L-23750
Funding Number(s)
CONTRACT_GRANT: FA9550-11-1-004
WBS: WBS 432938.11.01.07.43.30
Distribution Limits
Public
Copyright
Other