Nanotechnology: The new frontier for plastics
Monday, August 20, 2018
Not since the discovery of the silicon chip has there been this much excitement in the field of physics and material sciences. Innumerable universities have established nanocenters, with many receiving industrial funding and sponsorship, and a large number of these spawning nanomaterial-related entrepreneurial businesses spun out as the fruits of academic research.
Private industry and governments around the world are investing billions of dollars, rushing to exploit the small world that has been defined as materials under 100 nanometers in size.
Polymer nanocomposites are formed from blends of nanometer-sized fillers with either thermoset or thermoplastic polymers.
The properties of polymer nanocomposites are remarkably different from those of conventional materials. These altered properties include improved strength, toughness, heat distortion temperature, UV resistance, barrier properties, thermal and electrical conductivity.
Stated simply, the old rules don’t apply as new material capabilities are being envisioned.
Today's scientific adventure into the world of nanocomposites and nanotechnology has its origins in "There Is Plenty of Room at the Bottom," Richard Feynman’s 1959 address to the American Physical Society’s annual meeting at the California Institute of Technology.
"It is a staggeringly small world that is below," Feynman stated. Feynman, in addressing the prospects for a nanoworld questioned, "what would the properties of materials be if we could really arrange the atoms the way we want them? They would be very interesting to investigate theoretically." "I can hardly doubt that we will get an enormously greater range of possible properties that substances can have, and of different things that we can do. Atoms on a small scale behave like nothing on a large scale, for they satisfy the laws of quantum mechanics. So, as we go down and fiddle around with the atoms down there, we are working with different laws, and we can expect to do different things."
Feynman went on to assert, "The principles of physics, as far as I can see, do not speak against the possibility of maneuvering things atom by atom. It is not an attempt to violate any laws; it is something, in principle, that can be done; but in practice, it has not been done because we are too big.” One of the keys Feynman saw, to discovery and development at the nanoscale was “to improve the electron microscope by a hundred times."
Examples of objects, natural and produced, at the micro and nanoscales (Image: Plastics Institute of America)
Feynman was later to share the 1965 Nobel Prize in Physics with Sin-Itiro Tomonaga (Tokyo University of Education) and Julian Schwinger (Harvard University) for their "fundamental work in quantum electrodynamics, with deep ploughing consequences for the physics of elementary particles."
Let’s now turn our attention to nanocomposite market growth and related research commitments. Nanocomposites, comprising nanoclays and nanotubes, while still a small segment of the plastics industry, are expected to be a major growth area. These unique composite materials combine the best properties of filled thermoplastics and neat thermoplastics.
The use of polymer nanocomposites particularly in the automotive, packaging and electronics areas is growing steadily. Globally, average annual growth rates of nanocomposites use are projected to be between 18 and 25 percent per year with their use expected to reach close to $750 million by 2020.
The United States is the world leader in nanocomposites and nanotechnology research with, more than 800 research centers and companies involved and over $8 billion in funding as of 2017. By comparison, Europe has 250 companies and organizations participating in nanotechnology research and funding reaching $3 billion.
Japan is also making major investments in nanoscience research with approximately 150 companies pursuing nanotechnologies. Nanocomposites and nanoscience related government programs are underway on a global basis.
Even Thailand has announced that nanomaterials will play a major role in the country’s future economic development and has committed approximately 300 scientists to research in this field. Others in the developing world, including China, South Korea, Brazil, Chile, India, the Philippines, and South Africa have also demonstrated their commitment to nanotechnology by creating government funded nano-related programs and research institutes.
In terms of nanocomposite types, the nanocomposite field has grown much beyond nanotubes, nanoclays and nanoparticles, to include polyhedral oligomeric silsesquioxane (POSS, nanoparticles that combine organic and inorganic segments with nanosized cage structures) nanofibers, fibrils (MWNTs — Multi-Wall NanoTubes with closed ends), nanoplatelets (thin flakes, less than 5 nanometers thick), nanowires, and nanoyarns.
Nano-optical platelets promise to revolutionize the sensor and switching systems. Just around the corner are air bag sensors embedded into the outer polymer skin that transmit signals at the speed of light to buy microseconds of lifesaving time.
While many of the early nanocomposites have been formed using polypropylene and nylon as base polymers, nanocomposites have been formed with a wide variety of other resins including: epoxy, polyurethane, polyetherimide, poybenzoxazine, polystyrene, polycarbonate, polymethyl methacrylate, polycaprolactone, polyacrylontrile, polyvinyl pyrrolidone, polyethylene glycol, polyvinylidene fluoride, polybutadiene, copolymers and liquid crystalline polymers.
Delving further into nanocomposite applications, there is wide speculation that the improvements in tensile strength, modulus, and heat distortion temperature possible through the use of nanoclay-filled nanocomposites would lead to the replacement of existing engineering thermoplastics uses by nanocomposite versions of polyolefins and new nanocomposite versions of these displaced engineering thermoplastics will in turn challenge metal and glass applications in many new areas.
While there have been some commercial successes for nanoclay composite materials in structural applications, many of the early application successes have been more dependent on conductivity property improvements.
The automotive industry is leading the way in nanocomposite application development. Electroconductive nanopolymers have become the preferred composite materials for fuel delivery lines that are being converted from traditional steel to polymer. More than 70 percent of all cars built in the U.S. today incorporate nanotubes in fuel lines to prevent the accumulation of static electricity.
Electroconductive polymers also have been developed for electropaintable exterior body panel applications. The gaseous barrier property improvement achieved by incorporation of relatively small amounts of nanoclay materials is also substantial.
These exceptional barrier property improvements have created much interest in nanoclay composites for food packaging applications, for both bottle and film. The use of nanocomposite formulations is expected to considerably extend shelf life for many foods. Polymer-based nanocomposites are also being developed for electronics applications such as thin-film capacitors in integrated circuits, solid polymer electrolytes for batteries, micro-optical witches, nanoscale smart switches and sensors.
In the medical area, advances in nanocomposites are pushing the material envelop for minimally invasive devices. In this field, extremely thin walls and smooth surfaces are required.
Traditional fillers are too large to provide the homogeneous compounds needed for these thin wall applications. With nanocomposites, designers will have a much wider range of materials to select from for medical device designs. The industrial sector is also expected to see significant benefits through the use of nanocomposites.
In conclusion, the nanocomposites future is now.
Some proposed applications of nanocomposites and related studies are well advanced in research centers around the world. These projects include nanocomposites for automotive, aerospace and defense structures; polymer nanocomposite foams; nanocomposites for optic applications; conductive nanocomposites for corrosion protection, energy storage and conversion devices; nanofibers for tissue engineering scaffolding, protective armor and biosensing; and related life-cycle analysis of nanoparticles and nanocomposites.
Nanoparticles and nanocomposites in development can also serve as functional materials needed in application areas such as biomedical devices, drug delivery devices and photonics including optical displays, solar panels and so on.
Nanocomposite Applications under Development (Image: Center for Multifunctional Polymer Nanomaterials and Devices)
To help create the next generation of advanced, high-performance composites required for "smart" coatings, new construction materials, micro-electronic devices, "smart" medical implants chemical/biological sensors, faster/higher capacity "biochips" and so on, some materials researchers have turned to biomimicry.
Organisms have been creating and manipulating complex structures on the nanoscale for billions of years. Using DNA, RNA, and a huge variety of proteins, living cells build complex molecules, and nanoscale organelles, as well as create nonliving materials, such as tooth enamel and sea shells with nanoscale structures.
Nanotechnologists are logically seeking to duplicate techniques devised by organisms to create new nanocomposites and nanotools from the bottom up. One area of particular interest is the ceramic-like composites of mineral and biopolymers built by marine organisms that offer unique combinations of strength, biocompatibility, precise nanoscale structural control, and coupling systems between mineral/organic polymeric phases that make them especially attractive models for new materials. The remarkable ability of geckos to stick to almost any surface is a potential model for new adhesive surfaces.
As researchers’ understanding of the nano world grows and nanoscale science becomes applied to a host of products and devices, nanotechnology and the use of nanocomposites will introduce change in many details of our lives. We already benefit from some such achievements.
Special color effects in car paints are based on nanocomposites, as is a new scratch resistant car paint. Certain light weight car body panels and antireflection coatings on glasses and contact lenses also benefit from nanotechnology.
In the future, nanotechnology will have an important influence on many aspects of communications/information technology and medical devices/procedures.
New nanomaterials and nanocomposites such as advances as atomic switches, major increases in storage media capabilities, nano robots for repairs to the human body, artificial mechanical noses and ears are just a few of the developments which scientists are currently working on at research centers around the world. Many other nanocomposite-based ideas are just now unfolding. As Nobel Prize recipient Gerd Binning noted, "the nano age has only just begun."
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