DEWETTING OF THIN COLLAGENOUS PRECURSOR FILMS

We have studied structure formation of thin monomeric collagen films p repared by spin coating on hydrophobic highly oriented pyrolytic graph ite substrates. The biomolecular coatings have been investigated by sc anning force microscopy. Pattern formation takes place as the result o f dewetting of the liquid precursor initiated by pore nucleation in th e drying film. The growth of pores leads to an accumulation of collage n monomers along the perimeter of the dry patches formed. Depending on the evaporation velocity of the solvent, different well-defined film morphologies have been observed. The pore radius distribution function exhibits two well-separated peaks, indicating the occurrence of two d istinct dewetting mechanisms: heterogeneous pore nucleation and spinod al dewetting. The distribution function of the pores initiated by hete rogeneous nucleation is analysed in detail. A model is introduced that captures the main distribution features depending on humidity.