Two new polymers have been unveiled- codenamed Titan and Hydro, both of which came from the same reaction. One is rigid; it could become part of the next generation of computers. The other is a gel, so it it could be included in water-soluble nail polish. The new polymers are super strong, self-healing, lightweight, and easy to recycle and have potential to revolutionize manufacturing in the aerospace, semiconductors, automobile and micro-electronics industries. Through the unique approach of combining high performance computing with synthetic polymer chemistry, these new materials are the first to demonstrate resistance to cracking, strength higher than bone, the ability to reform to their original shape (self-heal), all while being completely recyclable back to their starting material. Also, these materials can be transformed into new polymer structures to further bolster their strength by 50% - making them ultra strong and lightweight.
IBM researcher Jeannette M. Garcia was among a team of nearly a dozen scientists and researchers who worked for more than a year on this discovery, and they are now submitting their findings to the peer review journal Science. Even though they were created from the same reaction, the two new polymers have distinct characteristics:
Titan is the stronger one. According to IBM, it has bone-like strength (its measurements were similar to the organic material that frames our bodies) and roughly one-third of the tensile strength of steel. When IBM researchers combined Titan with 2-5% carbon nanotubes, however, they found they could make a material three times stronger than the polyamides used on current aircrafts. Hydro is mostly liquid and quite flexible. It can also "self-heal"; according to Garcia, if you cut a blob of the polymer in two and then place the pieces next to each other (but don't force them together), they will combine back into one blob. One application could be for a powerful-on-contact adhesive. The gel-like polymer's other key feature is its ability to revert to its starting material in water. This can happen slowly, which means it could be set up as a time-release gel. It could also work in tougher materials like paint or nail polish that are removed with water, as opposed to acetone. Though quite different in makeup, the two polymers do share a common feature: Both are recyclable. Hydro is water-soluble, and Titan can, with a relatively light acid, be broken down into its components. This latter feature could potentially make polymer-based technology more recyclable than those built on non-recoverable polymers. The use of the polymers in electronics might mean the ability to recover valuable precious metals, like gold, that are used to carry the electrons around the circuits. "Right now, all the e-waste goes to landfill," he said. It could be months or even years before consumers see these polymers in action. Once the peer review is finished, IBM would need to find a manufacturer to produce Hydro and Titan in quantity.
These polymers, formed from the same inexpensive starting material through a condensation reaction, these molecules join together and lose small molecules as by-products such as water or alcohol and were created in an operationally simple procedure and are incredibly tunable. At high temperatures (250 degrees Celsius) the polymer becomes incredibly strong due to a rearrangement of covalent bonds and loss of the solvent that is trapped in the polymer (now stronger than bone and fiberboard), but as a consequence is more brittle (similar to how glass shatters). Remarkably, this polymer remain intact when it is exposed to basic water (high pH), but selectively decomposes when exposed to very acidic water (very low pH). This means that under the right conditions, this polymer can be reverted back to its starting materials, which enables it for reuse for other polymers. The material can also be manufactured to have even higher strength if carbon nanotubes or other reinforcing fillers are mixed into the polymer and are heated to high temperatures. This process enables polymers to have properties similar to metals, which is why these “composite blends” are used for manufacturing in airplane and cars. An advantage to using polymers in this case over metals is that they are more lightweight, which in the transportation industry translates to savings in fuel costs.
At low temperatures (just over room temperature), another type of polymer can be formed into elastic gels that are still stronger than most polymers, but still maintains its flexibility because of solvent that is trapped within the network, stretching like a rubber band. Probably the most unexpected and remarkable characteristic of these gels is that if they are severed and the pieces are placed back in proximity so they physically touch, the chemical bonds are reformed between the pieces making it a single unit again within seconds. This type of polymer is called a "self healing" polymer because of its ability to do this and is made possible here due to hydrogen-bonding interactions in the hemiaminal polymer network. One could envision using these types of materials as adhesives or mixing in with other polymers to induce self-healing properties in the polymer mixture. Furthermore, these polymers are reversible constructs which means that can be recycled in neutral water, and that they might find use in applications that require reversible assemblies, such as drug cargo delivery.
A team of scientists at IBM Research - Almaden have drawn upon years of expertise in semiconductor technology and material discovery to crack the code for safely destroying bacteria. For decades, bacteria like the stubborn methicillin-resistant Staphylococcus aureus (MRSA) have concerned gym goers, hospital patients and staff and parents of school children. What's particularly worrisome is that MRSA is not contained and killed by commonly available antibiotics. So, the bacteria can produce painful and sometimes deadly results for those who come in contact with it. In the United States alone, MRSA kills more than 19,000 people a year.
The IBM nanomedicine polymer program has looked to existing chip development research done at IBM, which identified specific materials that, when chained together, produced an electrostatic charge that allows microscopic etching on a wafer to be done at a much smaller scale. This new found knowledge that characterization of materials could be manipulated at the atomic level to control their movement inspired the team to see what else they could do with these new kinds of polymer structures. They started with MRSA. The outcome of that experiment was the creation of what are now playfully known as "ninja polymers" - sticky nanostructures that move quickly to target infected cells in the body, destroy the harmful content inside without damaging healthy cells in the area, and then disappear by biodegrading. "The mechanism through which [these polymers] fight bacteria is very different from the way an antibiotic works," explains Jim Hedrick, a polymer chemist in IBM Research. "They try to mimic what the immune system does: the polymer attaches to the bacteria's membrane and then facilitates destabilization of the membrane. It falls apart, everything falls out and there's little opportunity for it to develop resistance to these polymers."
Through the precise tailoring of the ninja polymers, researchers were able to create macromolecules - molecular structures containing a large number of atoms - which combine water solubility, a positive charge, and biodegradability. When mixed with water and heated to normal body temperature, the polymers self-assemble, swelling into a synthetic hydrogel that is easy to manipulate. When applied to contaminated surfaces, the hydrogel's positive charge attracts negatively charged microbial membranes, like stars and planets being pulled into a black hole. However, unlike other antimicrobials that target the internal machinery of bacteria to try to prevent it from replicating, this hydrogel destroys the bacteria by rupturing the bacteria's membrane, rendering it completely unable to regenerate or spread. The hydrogel is comprised of more than 90% water, making it easy to handle and apply to surfaces. It also makes it potentially viable for eventual inclusion in applications like creams or injectable therapeutics for wound healing, implant and catheter coatings, skin infections or even orifice barriers. It is the first-ever to be biodegradable, biocompatible and non-toxic, potentially making it an ideal tool to combat serious health hazards facing hospital workers, visitors and patients.
The IBM scientists in the nanomedicine polymer program along with the Institute of Bioengineering and Nanotechnology have taken this research a step further and have made a nanomedicine breakthrough in which they converted common plastic materials like polyethylene terephthalate (PET) into non-toxic and biocompatible materials designed to specifically target and attack fungal infections. BCC Research reported that the treatment cost for fungal infections was US$3 bln worldwide in 2010 and is expected to increase to US$6 bln in 2014. In this breakthrough, the researchers identified a novel self-assembly process for broken down PET, the primary material in plastic water bottles, in which 'super' molecules are formed through a hydrogen bond and serve as drug carriers targeting fungal infections in the body. Demonstrating characteristics like electrostatic charge similar to polymers, the molecules are able to break through bacterial membranes and eradicate fungus, then biodegrade in the body naturally. This is important to treat eye infections associated with contact lenses, and bloodstream infections like Candida.