Methods are provided for a one step synthesis of polypeptide polymers or co-polymers. The polymers or co-polymers can be linear or branched. In the methods of the invention, the coding sequence for the polypeptide(s) to be polymerized is altered by introducing one or more codons for an nonnatural amino acid, which coding sequence is then utilized to produce the cognate polypeptide. The nonnatural amino acids are selected to be reactive with each other in a bioorthogonal reaction, and are combined in a conjugation reaction with the desired components of the polymer.