I feel quite strongly that pollution is an evil and nefarious menace; it kills plants and animals, probably causes cancer, and coats everything on your street-facing balcony with a layer of dark brown powdery sludge that means you have to toss heavy buckets of water over your white metal patio furniture anytime you have guests over. I’m sure you know exactly what I’m talking about.

1952 | London Smog – Image courtesy ptkeepcalmcarryon.blogspot.com

Anyway – as I mentioned, I am deeply opposed to pollution in many of its forms, and I’m thinking of founding a formal opposition group to host regular meetings following strict Parliamentary procedure. The formal opposition group will commit ourselves as a first order of business to obtaining some newfangled “pollution glue” aka “dust suppressant” that the city of London is planning to spray on “15 separate stretches of road in areas with especially bad air quality” in order to trap pollutants (Price). If left unchecked, these polluting particles will get sucked into the lungs of  innocent bystanders in the widespread and perfectly understandable habit of breathing. This must be stopped.

The pollution glue is a non-toxic, biodegradable, saline solution with calcium magnesium acetate. Converted winter service trucks will spray it on the streets of London at night like so many machine-like dogs marking so many road-like fire hydrants. The glue will have to be reapplied frequently since rain has a tendency to wash the solution away into drains and traffic wears it off the surface of the street.

Image courtesy nj.gov

The dust suppressant can’t trap carbon monoxide or other gas-based pollutants, but it will make it easier to breathe the air around central London: preliminary tests showed a 10-14% reduction in particulate matter with a diameter of 10 micrometers or smaller (Price). The city is in a rush to improve urban air quality because London faces steep fines for violating PM-10 limits set by the European Union.

When I heard about pollution glue, I was all excited because it seems brilliant and tidy to trap nasty particles before we inhale them. Not only that, I thought, the glue is non-toxic so it won’t harm the environment. But then I realized that anything that traps industrial particulates (even if the material itself is not made of nasty chemicals) will essentially become extremely toxic as it rounds up pollutants – and so instead of breathing in evil dust, Londoners may simply be allowing it to run into their watershed in a more concentrated form.

And perhaps more fundamentally, the glue does nothing to discourage industry from emitting the particulates in the first place. What do you think?

WU XING:

I’m filing pollution glue under Fire because fire makes smoke and particles and I sense that pollution glue would be fond of it.

Cited:

Price, Andrew. “A ‘Pollution Glue’ Gets Sticky with Pollution, Improves Air Quality.” fastcoexist.com 01/11/12. Accessed 1/12/12. URL.

There are three types of people in the world: those who carefully transport insects and arachnids out of the building on sheets of paper, releasing them into the wild to roam free, bite innocent people, and reproduce; those who whip off their hard-soled shoes and gleefully smash anything with an exoskeleton that happens to wander within range; and those for whom the thought of a particularly nasty bug is enough to inspire a scream-enhanced instinctive high-speed run headlong into another room.

I belong to the last category, and thus it is with great trepidation and reluctance that I write about a new body of research out of the University of Akron that examines a pair of spider glues with useful properties.

I’ve read about work people are doing with spider silk threads (the silk tends to be amazingly strong – much stronger than kevlar, for instance, which is the material Superman would have adopted as his benchmark had it been more prevalent back in the day). But until recently I hadn’t stopped to think about what makes spiderwebs such a menace to society and to gnats, namely: they are sticky.

Image courtesy socypath.com

So as it turns out, to my abject horror, there are at least two general types of web-weaving spiders and they use the same set of glands to produce two different types of sticky silk-coating glue.

The first type, orb-weaving spiders, have been around pretty much since the dawn of time, and they produce something called viscid glue, a “glue that acts like a viscoelastic solid. Highly humidity-sensitive, this glue expands in magnitude and demonstrates a monotonous increase in elasticity under increased humidity. The glue also displays a decrease in surface adhesion that results in optimal adhesion at intermediate humidity” (physorg.com). Viscid glue can become stickier or less sticky depending on the humidity level.

The other type of spider, your garden variety cobweb-weaving spider,  is a direct descendant of the orb-weavers but produces gumfoot glue, an adhesive material that differs in structure, properties, and response to humidity.  Gumfoot glue “acts as a viscoelastic liquid that is resistant to changes in humidity, consequently maintaining constant elasticity and adhesion” (physorg.com).  So even when these spiders live in New Orleans or Hotlanta, the glue they produce maintains a consistent level of stickiness.

To figure out how glue from the two types of spiders differed, the research team took individual drops of glue and stretched them at different humidity levels. Observing that viscid glue behaved like a viscoelastic solid and that the gumfoot glue behaved like a viscoelastic liquid, the researchers designed a polymer model of the glue droplets to understand the mechanisms at work behind the responses.

Image courtesy coolphotoideas.com

Understanding the behavior patterns of natural biomaterials, such as spider glue, provides us with insight we can use to develop smart materials and devices that may undergo changes in dimension, properties, and function in response to changes in the environment.  Investigating changes wrought by evolution provides us with a means of advancing biomimetic research (research that seeks to understand and mimic nature, Leonardo DaVinci-style).  This line of thinking could lead to new adhesives with applications in buildings in humid environments, among other things – and that is why I braved a “spider” keyword Google search in order to illustrate this post.

WU XING:

I have filed this adhesive under WOOD and WATER, for reasons known only to myself.

Cited:

“Spider Silk Glue Inspires Next-Generation Technology.” Physorg.com 7/22/11. Accessed 7/22/11. URL.

Vasav Sahni, Todd A. Blackledge & Ali Dhinojwala. “Changes in the Adhesive Properties of Spider Aggregate Glue During the Evolution of Cobwebs.” Scientific Reports 7/21/11. Accessed 7/22/11. URL.