The scope of this Perspective is to highlight innovative contributions in the synthesis of well-defined complex macromolecular architectures and to emphasize the importance of these materials to polymer physical chemistry, physics, theory, and applications. In addition, this Perspective tries to enlighten the past and show possible pathways for the future. Among the plethora of polymerization methods, we briefly report the impact of the truly living and controlled/ living polymerization techniques focusing mainly on anionic polymerization, the mother of all living and controlled/living polymerizations. Through anionic polymerization well-defined model polymers with complex macromolecular architectures having the highest molecular weight, structural and compositional homogeneity can be achieved. The synthesized structures include star, comb/graft, cyclic, branched and hyberbranched, dendritic, and multiblock multicomponent polymers. In our opinion, in addition to the work needed on the synthesis, properties, and application of copolymers with more than three chemically different blocks and complex architecture, the polymer chemists in the future should follow closer the approaches Nature, the perfect chemist, uses to make functional complex macromolecular structures by noncovalent chemistry. Moreover, development of new analytical methods for the characterization/purification of polymers with complex macromolecular architectures is essential for the synthesis and properties study of this family of polymeric materials.

Two well-defined cyclic triblock terpolymers, missing pieces of the terpolymer morphology puzzle, consisting of poly(isoprene), polystyrene, and poly(2-vinylpyridine), were synthesized by combining the Glaser coupling reaction with anionic polymerization. An α,ω-dihydroxy linear triblock terpolymer (OH-PI 1,4 -b-PS-b-P2VP-OH) was first synthesized followed by transformation of the OH to alkyne groups by esterification with pentynoic acid and cyclization by Glaser coupling. The size exclusion chromatography (SEC) trace of the linear terpolymer precursor was shifted to lower elution time after cyclization, indicating the successful synthesis of the cyclic terpolymer. Additionally, the SEC trace of the cyclic terpolymer produced, after cleavage of the ester groups, shifted again practically to the position corresponding to the linear precursor. The first exploratory results on morphology showed the tremendous influence of the cyclic structure on the morphology of terpolymers.

Statistical and block copolymerization of poly(L-lactide) (PLLA) and poly(ε-caprolactone) (PCL) macromonomers having an end-norbornenyl group was performed via ring opening metathesis polymerization, ROMP, to produce the corresponding statistical and block brush copolymers consisting of PLLA and PCL side chains on a polynorbornene, PNBE, backbone. The molecular characteristics of the macromolecular brushes were determined by 1 H-NMR spectroscopy and Size Exclusion Chromatography equipped with various detectors. These complex topologies allow addressing important questions on the physics of semicrystalline polymers. These include the role of (i) a doubly grafted PCL or PLLA chain on

Poly(macrolactones) (PMLs) can be considered as biodegradable alternatives of polyethylene; however, controlling the ring-opening polymerization (ROP) of macrolactone (ML) monomers remains a challenge due to their low ring strain. To overcome this problem, phosphazene (t-BuP 4), a strong superbase, has to be used as catalyst. Unfortunately, the one-pot sequential block copolymerization of MLs with small lactones (SLs) is impossible since the high basicity of t-BuP 4 promotes both intra-and intermolecular transesterification reactions, thus leading to random copolymers. By using ROP and the "catalyst-switch" strategy [benzyl alcohol, t-BuP 4 /neutralization with diphenyl phosphate/(t-BuP 2)], we were able to synthesize different well-defined PML-b-PSL block copolymers (MLs: dodecalactone, ω-pentadecalactone, and ωhexadecalactone; SLs: δ-valerolactone and ε-caprolactone). The thermal properties and the phase behavior of these block copolymers were studied by differential scanning calorimetry and X-ray diffraction spectroscopy. This study shows that the thermal properties and phase behavior of PMLs-b-PSLs are largely influenced by the PMLs block if PMLs components constitute the majority of the block copolymers.

Tadpole polymers are excellent candidates to explore how architecture can influence self-assembly because they combine two topologies in the same molecule (ring polymer as the head and linear polymer as the tail). In this work, we synthesize well-defined tadpole homo-/co-/terpolymers derived from the appropriate chemical modification reactions of the corresponding 3-miktoarm star homo-/co-/ terpolymers via anionic polymerization, high vacuum techniques, and chlorosilane chemistry in combination with the Glaser coupling reaction. The 3-miktoarm star homo-/ co-/terpolymers bear two arms with t-butyl dimethylsiloxypropyl functional end-groups, whereas after deprotection, the ωhydroxyl chain-ends were modified to alkyne moieties. The dialkyne star polymers in the presence of Cu(I)Br and N,N,N′,N″,N″-pentamethyldiethylenetriamine were then transformed to well-defined tadpole homo-/co-/terpolymers. We employed strongly immiscible blocks to enable characterization using electron microscopy and X-ray scattering to explore how the molecular topology influences the self-assembled bulk-state microdomain morphologies.