The objective of the present thesis was the preparation of complex macromolecules by the combination of controlled/livingpolymerization methods such as ring-opening (metathesis) polymerization (RO(M)P) and highly efficient orthogonal chemistries: copper-catalyzed azide-alkyne coupling (CuAAC) and thiol-ene reactions.In the first part of this work, a series of well-defined structural (co)polymers containing a cycloolefin (norbornene (NB) oroxanorbornene (ONB)) functionality bearing two polymer chains including poly(ε-caprolactone) (PCL) and/or poly(ethylene oxide) (PEO) have been successfully prepared using the combination of ring-opening polymerization (ROP) and CuAAC ‘click’ chemistry. Well-defined (oxa)norbornenyl-functionalized bis-PCL polymers with PCL chain ranging from 1400 to 5000 g/mol were obtained by organocatalyst-mediated ROP. Norbornenyl-functionalized PEO-b-PCL block copolymers with PCL block in the range 1100 to 4100 g/mol were synthesized from commercially available PEO 2000 g/mol by CuAAC followed by ROP of CL. The presence of a hydrophilic PEO chain and a hydrophobic PCL chain in norbornenylfunctionalizedPEO-b-PCL copolymers gives rise to self-assembling properties in water solution. Critical micellar concentrations (CMC)are in the range of 0.08 – 0.006 g/L for copolymers with PCL chain length ranging from 10 to 36 CL units, respectively. Thecorresponding micelles show hydrodynamic diameters in range of 10 – 23 nm with low polydispersities.In the second part of this work, well-defined copolymers were used to prepare bottle-brush and (mikto-arm) star copolymersthrough reactions involving the cycloolefin functionality. On the one hand, high density grafting bottle-brush copolymerspoly(oxa)norbornene-g-bisPCL, polynorbornene-g-PEO/PCL (PNB-g-(PEO/PCL)) and PNB-b-(PNB-g-(PEO/PCL)) were achieved by ROMP according to the ‘grafting through’ strategy using Grubbs’ catalysts. On the other hand, PCL, PEO, PNIPAM-based 3-arms star, 4-arms star copolymers were obtained via radical thiol-ene reactions as demonstrated by 1H NMR, SEC and MALDI-ToF MS analysis.The high reactivity of these copolymers toward ROMP and thiol-ene reactions makes them interesting candidates in order toprepare new well-defined copolymers with controlled structures and properties through highly efficient synthetic strategies.