Unconventional high-temperature superconductivity from repulsive   interactions: theoretical constraints
  Unconventional symmetries of the order parameter allowed some researchers to maintain that a purely repulsive interaction between electrons provides superconductivity without phonons in a number of high-temperature superconductors. It is shown that the Cooper pairing in p and d states is not possible with the realistic Coulomb repulsion between fermions at relevant temperatures in any dimension. 
A. S. Alexandrov and V. V. Kabanov
cond-mat.supr-con cond-mat.str-el