Gratings are written holographically with low power \left(10\text{mW}/{\text{cm}}^{\text{2}}\right) 244\text{\hspace{0.17em} nm} UV light on thin films of polybutadiene rubber polymer. The increase of hydrophilicity–wettability of polybutadiene films is measured over UV-exposed regions. Sequential fabrication of two orthogonal gratings results in hydrophilic microarrays having applications as functionalized substrates for immobilizing biomolecules. This is demonstrated by immobilizing a phospholipid in a microarray pattern.