Methods of forming an electronic device comprise: (a) providing a semiconductor substrate comprising a porous feature on a surface thereof; (b) applying a composition over the porous feature, wherein the composition comprises a polymer and a solvent, wherein the polymer comprises a repeat unit of the following general formula (I): wherein: Ar1, Ar2, Ar3 and Ar4 independently represent an optionally substituted divalent aromatic group; X1 and X2 independently represent a single bond, —O—, —C(O)—, —C(O)O—, —OC(O)—, —C(O)NR1—, —NR2C(O)—, —S—, —S(O)—, —SO2— or an optionally substituted C1-20 divalent hydrocarbon group, wherein R1 and R2 independently represent H or a C1-20 hydrocarbyl group; m is 0 or 1; n is 0 or 1; and o is 0 or 1; and (c) heating the composition; wherein the polymer is disposed in pores of the porous feature. The methods find particular applicability in the manufacture of semiconductor devices for forming low-k and ultra-low-k dielectric materials.