Synthetic DNA analogues are of great interest for their application in information storage, therapeutics, and nanostructured materials, yet are often limited in scalability. Vinyl sulfonamide click nucleic acids (VS-CNAs) have been developed to overcome this limitation using the highly efficient thiol-Michael 'click' reaction. Utilizing all four nucleobases, sequence-defined click nucleic acids (CNAs) were synthesized using a simple and scalabale solution-phase approach. Employing a polyethylene glycol (PEG) support, synthesis of the CNA sequence, GATTACA, was achieved in high yields. CNA crosslinked hydrogels were assembled using multiarm PEG-CNAs resulting in materials that dynamically respond to temperature, strain, and competitive sequences.