A process for recovering materials from a subterranean formation, for example in enhanced oil recovery, comprises: (A) (a) (i) selecting a first polymeric material having a repeat unit of formula (A) wherein A and B are the same or different, are selected from optionally-substituted aromatic and heteroaromatic groups and at least one comprises a relatively polar atom or group and R.sup.1 and R.sup.2 independently comprise relatively non-polar atoms or groups; or (ii) selecting a first polymeric material prepared or preparable by providing a compound of general formula (B) wherein A, B, R.sup.1 and R.sup.2 are as described above, in an aqueous solvent and causing the groups C.dbd.C in said compound to react with one another to form said first polymeric material; (b) selecting a second polymeric material which includes a functional group which is able to react in the presence of said first polymeric material to form a third polymeric material; (c) causing the formation of said third polymeric material by a reaction involving said first and second polymeric materials; and (d) contacting the subterranean formation with said third polymeric material; or (B) contacting the formation with a polymeric material (hereinafter "said third polymer material") which is a product of a reaction involving: (a) a first polymeric material as described in (A) (a) (i) or (ii); and (b) a second polymeric material which includes a functional group which is able to react in the presence of said first polymeric material to form said third polymeric material. ##STR00001##