After having a couple of problems undoing plastic connectors due to age, both mine and the said connectors (entropy ?) I find myself wondering if there is anything a coating or something available to prevent this happening.

Unfortunately, a lot of the plastics used nowadays don't appear to live up to their reputation of being indestructible, particularly when cold, they can become very brittle. I don't know of any specific coating to combat this other than to say that some, WD40 or similar for example can shorten the life of some plastic parts.

I remember many years ago there was a particular brand of monochrome TV that came in a moulded thermoplastic case, this particular TV used to suffer with "noisy' controls, Ie, the volume would crackle or brightness would flicker when adjusted, the usual solution to this was to squirt copious amounts of switch cleaner into the controls, after a few years, these sets would be coming into the workshop with the bottom of the cabinet having disintegrated under their own weight.

I Like Chips wrote:

After having a couple of problems undoing plastic connectors due to age, both mine and the said connectors (entropy ?) I find myself wondering if there is anything a coating or something available to prevent this happening.