Your description makes it sound very like Parylene which rawbrawb mentioned.
Wikipedia - Parylene
Paratech - Parylene 'experts'
...and much more.
BUT other mentions on web make it sound less so.
So that I am actually answering at least part of your question :-).
Does anyone know a chemical that would work in this way?
Answer: Apparently not, and include Liquipel amongst them.
There are a number of reports of it not working with valuable equipment under well-enough-controlled circumstances.
For the very large amount of money paid (I've seen $60 and $100 mentioned) it seems a very poor deal.
(1) Here is an online fails in front of your eyes You Tube video
Full immersion at of an iPhone about 29:30 - about 7 seconds immersed. Video start slightly before then.
and end result about 1 hour later here. Reportedly, they had ruder things to say post-show.
(2) Here is an Australian product testing site report.
- To try out the process we had Liquipel applied to an iPhone 3GS and an iPad 2, lodged via separate retail outlets on different days.
- So, we did our own full-immersion experiment in the CHOICE labs, dunking both our devices in a tub of water to see if they would be immune.
Unfortunately, they weren't. Both devices malfunctioned almost immediately. And, despite being thoroughly drained and dried over several days, neither device recovered.**
UPDATE: After several weeks of drying out and periodic re-checking, the iPhone has not recovered any useability at all. The iPad, however, has regained some functionality.
The water markings on the inside of the display screen faded noticeably after about three weeks and the iPad appears to be mostly usable but the hardware Power/Sleep button at the top edge is still NOT working at all, so it can't be used to put the device to sleep, wake it up or shut it down completely.
The workaround for the sleep/wake function is to use an Apple magnetic SmartCover or to enable the Assistive Touch software options under the Accessibility menu. This presents a software option onscreen that can be used to put the iPad to sleep. However, you can't use this to turn it off. So, for example, it couldn't be taken on a plane because electronic devices must be turned off completely for takeoff and landing.
They added: Liquipel is obviously confident in its claims, providing samples of Liquipel-treated paper tissue with each device returned from treatment. We also subjected them to water to see how they held up. Initial results showed that the process appears to provide a certain amount of water repellency, but from the results we obtained with our electronic devices, obviously we can’t recommend this treatment.