Final Report: A Versatile Biomimetic Approach to Environmentally Friendly and Energy-Efficient Processing of Nanostructured Composites

EPA Contract Number: EPD04048
Title: A Versatile Biomimetic Approach to Environmentally Friendly and Energy-Efficient Processing of Nanostructured Composites
Investigators: Chowdhury, Habibur
Small Business: Technova Corporation
EPA Contact: Manager, SBIR Program
Phase: I
Project Period: March 1, 2004 through August 31, 2004
Project Amount: $70,000
RFA: Small Business Innovation Research (SBIR) - Phase I (2004) RFA Text |  Recipients Lists
Research Category: Nanotechnology , SBIR - Nanotechnology , Small Business Innovation Research (SBIR)

Description:

The environmentally friendly, low-cost, and energy-efficient layer-by-layer self-assembly technique was developed as a versatile and efficient means of processing nanocomposite structural and coating systems. The self-assembly process is a soft-solution technique that provides for: (1) processing of hybrid, multifunctional nanocomposites comprising organic/inorganic and structural/functional constituents, (2) molecular-level control over structural buildup, and (3) strictly limited flaw size and thus greatly enhanced performance attributes. The goals of this research project were to: (1) process nanocomposites within cellular precursors to develop efficient structural systems, (2) analyze the modeling of nanocomposite materials and structural systems, and (3) develop nanocomposite protective coatings.

Summary/Accomplishments (Outputs/Outcomes):

Development of Efficient Nanocomposite Structural Systems

Technova Corporation developed a biomimetic structural system through deposition of nanocomposites onto cellular precursors. Aluminum and polyurethane cellular precursors were considered, onto which various nanocomposites comprising inorganic nanoparticles/nanoplatelets and carbon nanotubes as well as polymer matrix systems were self-assembled. The end products were evaluated through mechanical tests, which led to the following findings:

  • The self-assembly process can be adapted towards development of diverse nanocomposites comprising different combinations of nanoparticles, nanoplatelets, nanotubes, and polymer matrices at various volume fractions. Both ceramic/ceramic and polymer matrix nanocomposites can be processed via self-assembly.
  • Nanolayered ceramic/ceramic nanocomposites, processed through self-assembly of ceramic nanoparticles, offer enhanced mechanical attributes that exceed those of their constituents and thus the law-of-mixtures predictions. These findings can be explained by the effects of nanospaced interfaces on the size, density, and propagation of defects within nanolayered composites.
  • Polymer matrix nanocomposites with high-volume fractions of carbon nanotubes can be processed via self-assembly, with post-processing steps ensuring crosslinking and desirable bonding of the matrix to nanotubes.
  • Self-assembled carbon nanotube/polymer nanocomposites benefit from the introduction of nanoparticles and especially nanoplatelets; the system comprising nanoplatelet layers with nanotube-reinforced polymer binder, which mimics the nanostructure of natural load-bearing materials such as bone and shell, offer particularly high levels of specific strength.
  • The self-assembly process can be adapted towards selective deposition of nanocomposites along load paths within cellular precursors, yielding optimum biomimetic structural systems with enhanced performance-to-weight ratios.

Modeling of Nanocomposite Materials and Structures

Semi-empirical material models were developed for the mechanical performance of nanolayered composites. Multiscale models were developed for structural systems comprising nanocomposites built upon cellular precursors. These structural models embody the nanocomposite material models, and they were used to verify the gains in structural efficiency brought about by the emerging generations of nanocomposites. The structural models were expanded to cover optimized structural systems with nanocomposites deposited along load paths for optimum performance. These models proved to be effective design tools for optimum use of nanocomposites in the context of structural systems.

Development of Nanocomposite Protective Coatings

Structural systems rely on their outer skin to resist the aggressive elements of their environment, including erosion, impact, ultraviolet (UV) radiation, elevated temperatures, acids, and corrosive chemicals. Layer-by-layer self-assembly of nanocomposites enables development of gradient structures, with outer skins specifically designed for environmental resistance. Nanocomposite protective coatings were designed to resist the effects of elevated temperatures, provide effective barrier qualities, resist UV radiation, and provide erosion/impact resistance. These nanocomposites employ various nanoplatelets, nanoparticles, and nanotubes, mostly in the context of crosslinked polymer matrices, for effective protection of various substrates against aggressive elements of the environment. Experimental results verified the advantages of nanostructuring in achieving enhanced protective attributes.

Conclusions:

The environmentally friendly layer-by-layer self-assembly technique was validated as a powerful, versatile, and economical means of processing nanocomposites that can fully exploit the tremendous physical and mechanical potentials of nanotubes, nanoplatelets, and nanoparticles. The layer-by-layer self-assembly technique enables sequential introduction of different nanoscaled ingredients and matrix systems, with controlled bonding and thorough integration of the constituents into high-performance, multifunctional nanocomposites. Self-assembly effectively overcomes the problems with homogeneity and bonding, which are encountered with alternative means of processing nanocomposites. Diverse categories of nanocomposites can be processed via self-assembly, yielding superior mechanical, barrier, and thermal qualities. Self-assembled nanocomposites can be processed within cellular precursors, yielding biomimetic structural systems of high performance-to-weight ratios. Selective self-assembly of nanocomposites along load paths within cellular precursors provides for further gains in structural efficiency.

Supplemental Keywords:

biomimetic structural systems, nanostructured composites, self-assembly, coating systems, carbon nanotube, nanoparticle, nanoplatelet, polymer matrix, SBIR,, RFA, Sustainable Industry/Business, POLLUTION PREVENTION, Sustainable Environment, Energy, Technology for Sustainable Environment, nanocoatings, nanotechnology, aerospace structures, biomimetic synthesis, energy efficiency, engineering, environmentally applicable nanoparticles