High surface area coatings are applied to solid substrates to increase the surface area available for solid-phase synthesis of polymers. The high surface area coatings use three-dimensional space to provide more area for functional groups to bind polymers than an untreated solid substrate. The polymers may be oligonucleotides, polypeptides, or another type of polymer. The solid substrate is a rigid supportive layer made from a material such as glass, a silicon material, a metal material, and plastic. The coating may be thin films, hydrogels, microparticles. The coating may be made from a metal oxide, a high-κ dielectric, a low-κ dielectric, an etched metal, a carbon material, or an organic polymer. The functional groups may be hydroxyl groups, amine groups, thiolate groups, alkenes, n-alkenes, alkalines, N-Hydroxysuccinimide (NHS)-activated esters, polyaniline, aminosilane groups, silanized oxides, oligothiophenes, and diazonium compounds. Techniques for applying coatings to solid substrates and attaching functional groups are also disclosed.