Hi lotsarsrch.
I am not a foam chemist but generally speaking copper (Cu) would have an oxidative effect as copper is an oxygen carrier. In addition to this the presence of grease or oils would facilitate the copper oxidation) Research papers (such as this paper here) attribute the action of copper to the formation of copper chloride which acts as an oxidative accelerator.
Some of the latex producers use fillers in their specialty products (such as TGs “Talalay mineral”) but the Cu in it is microencapsulated as to mitigate the antagonistic impact copper has against latex. and is also used to improve the processability and heat transfer (due to the increased surface area) of the PCM. The amount of Cu that is added to the latex is, of course, part of a formulation which is proprietary, but it would be done in such a quantity as to not negatively impact durability. The benefits of Cu used as a filler in both memory foam and latex are connected with its thermo-conductive properties, I know that copper fillers in Memory foam and latex are advertised as having side “health benefits” (like copper bracelets) but to my knowledge, these benefits have not been proven in copper infused foams. The main benefit for adding Cu to latex or memory foams would be for thermal conductivity (which generally is not an issue with latex, to begin with) so I personally would not make a priority to choose one over the other (with or without copper)
You can read more about phase change materials in post #9 here and The effects of Copper on rubber in Some of the effects of the copper nanowire Cu NW in this recent study here
Outlast materials are normally used in a ticking or in bedding products (sheets, protectors) materials that use Phase Change Materials to proactively regulate body temperature through a continuous cycle of absorbing the heat from the body when the skin cools the absorbed heat is released back to the body. I’ve had no personal experience with Outlast to know to what degree this is better at regulating temperature than wool (which does this by wicking away moisture), but you can see some of the benefits of bedding of the outlast technology. And also a brief explanation of the testing that is conducted by Outlast’s director Volker Shuster and Christoph Russ (owner of c.russ-netconsult) in this Video here that shows that outlast materials can significantly reduce moisture.
I hope this adds to the Phase Change Materials picture
Phoenix