The photoinduced copper(I)-catalyzed polymerization of multifunctional azides and alkynes is facilitated by the photoreduction of copper(II) acetate generating copper(I) ions without using any additional photoinitiator. The polymerization can only be carried out in solution using at least 15 wt% of methanol. Depending on the catalyst concentration quantitative monomer conversions can be achieved allowing the determination of the mechanical properties. The bifunctional system consisting of a di-azide and di-alkyne exhibited the highest Young's modulus value of 1600 MPa.