Hi Sameera..
first i have to know what you mean with "chemistry of the polymer while curing". Then i'd like to know what polymer you are referring to.
With certain resins, the amount of pressure will influence the outcome. PU's might be more or less foamy as mentioned earlier in this thread, but that is not a change in chemistry. The general curing mechanisms can only change with increasing pressure, if part of the mechanism is an equilibrium with a volatile or gaseous component on one end, which isn't very likely to take effect within reasonable pressure boundaries. Also would this not be a "change in chemistry", might however lead to a different resin.
Or do you refer to polymerisation reactions? Then of course the pressure is very important when it comes to volatile or gaseous monomers as for example in polyethene production: high presure gives low density branched PE, while low pressure give mainly linear HDPE.
pls give us some more input
cheers
dave