Polymer-based
molecular object
(one of >10500 alternatives)
Molecular objects made of a nylon-like, high-performance polymer are among the most impressive nanostructures in existence today, and I expect structures like these to be used in developing advanced, atomically precise nanotechnologies in the coming years. This high-performance polymer is really more of a construction kit: Its monomeric parts can be hooked up to make atomically precise structures that self-assemble to form materials with a wide range of mechanical properties, ranging from rubber-like elastomers to strong, stiff fibers used in bulletproof vests, and these mechanical properties give no more than a hint of the vast range of device applications.
Designers can access over 10500 alternative polymer-based structures, each made by hooking together a series of a few tens to a few hundreds of monomeric building blocks. Adequate methods of synthesis are well-established. What makes this technology so powerful and flexible is that each kind of building block carries with it not only two functional groups that join to link the blocks, but a third structure that has a unique size, shape, and set of chemical properties. These provide (in overlapping categories) hydrocarbon chains, hydrogen-bond donors and acceptors, acids, bases, positive and negative charges, and more.
Building larger structures
These diverse structures can be bundled together with atomic precision to form a complex object just a few nanometers in size. This isn’t a size limit, though, because their atomically precise surfaces can match specific other surfaces, enabling them to fit together to form even larger structures by self-assembly.
These polymers can bind together other polymers, too, as well as ceramics, semiconductors, and metals. This gives them great promise for use in hybrid, composite nanosystems that join together diverse nanostructures and nanodevices in a precise and controlled way.
This material has become a prototype for other polymers with different structures and properties, but similar versatility. It should be thought of not just as one kind of material (or construction kit), but as the first of a family of materials for building atomically precise nanosystems.
Difficulties
At the moment, the main limit to progress is the limited capabilities of the necessary design software, but improvements are ongoing. There’s an enormous incentive to develop better design capabilities, because trial-and-error methods — often too slow for practical use — indicate that the range of products can include not just structural materials, but sensors, catalysts, and active mechanical and electronic devices.
Although work in this area is making amazing progress, it’s been amazingly underfunded. A large and growing effort goes into scientific investigation of this class of materials and nanostructures, but the effort going into engineering is a tiny fraction of this. I would have expected that the boom in nanotechnology would have driven research forward — pushing hard — yet to my astonishment the field has languished on the sidelines, and often isn’t thought of as being a nanotechnology.
Instead of being developed as a cutting-edge nanotechnology, this engineering toolkit been studied almost exclusively by biologists, and it is burdened by a strong and distracting reputation that stems from this biological connection. The most basic problem, I suspect, is that products made with this engineering toolkit are commonly thought of as being inherently soft and soggy, simply because they form the nanofibers and linear motors found in meat.
This engineering polymer is called “protein”, and because they eat it, people who know almost nothing about it are under the impression that they know what it is, and what they think they know is usually quite wrong.
I think that this is a problem. The opportunity costs are staggering.
Update, 28 Dec 2009: I’ve recently been using the terms “polypeptide” or “peptide polymer” in many instances where one might instead use “protein”. These are accurate and familiar terms, and they embraces both non-protein peptide assemblies and protein-like structures made from non-biological monomers. Best of all, they don’t evoke thoughts of meat.
See also:
- Modular Molecular Composite Nanosystems
- Toward Advanced Nanotechnology: Nanomaterials (2)
- Self-Assembly for Nanotechnology
- Design Software for Atomically Precise Nanotechnologies
- CAD for Nanoengineering: DNA, proteins, and search-intensive design
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Scott Jensen 03.20.09 at 2:56 am UTC
So what do you suggest for a solution to the problem?
Eric Drexler 04.01.09 at 4:01 am UTC
Scott, I can only suggest that people who write and speak about topics in this area take care to understand the facts and the need to communicate them. Surprising facts can be good to include in many contexts, and all the more so when they’re important.