While there may not be a reaction with the copper you should realize that insulation only slows the freezing process but does not stop it entirely.
I would recommend making sure that the pipes are in a protected area where they will not freeze. I.E. instead of putting them in an outside wall having them come up out of the floor for a sink or, toilet.
If they do freeze and burst or, start to leak when encased in foam they will be much more difficult to repair. I would use a more easily removed insulation.