Densely Packed Multicyclic Polymers

Abstract

Highly dense polymer chains were formed through coupling cyclic polymeric units in a sequence controlled manner. It was found that as the number of cyclic units increased the compactness substantially increased in a good solvent to a limiting value after only 12 units. This limiting value was close to that of a linear polymer chain in a θ solvent, in which polymer segment interactions with solvent are minimized. This remarkable result suggests that the unique architecture of the cyclic structure plays an important role to significantly change the polymer conformation and remain soluble in solution, which circumvents the need for crosslinking. The insight found in this work provides a physical mechanism as to why Nature uses cyclic structures in proteins to confer stability and the compacting of DNA strands to induce chromosome territories.

Rhodanine-based Knoevenagel reaction and ring-opening polymerization for efficiently constructing multicyclic polymers

“…Satoh, Isono and coworkers developed the ring-opening metathesis cyclopolymerizations of α,ω-norbornenyl end-functionalized macromonomers to prepare multicyclic polyesters and polyethers 28 . Furthermore, Monteiro and Tezuka also reported the synthesis of interesting densely packed 29 and knotted multicyclic polymers 30,31 , respectively. However, although important progresses have been made, fast and large-scale preparation of complex multicyclic polymers via ring-expansion strategy is still unreachable.…”

Topologically Reversible Transformation of Tricyclic Polymer into Polyring Using Disulfide/Thiol Redox Chemistry

“…1 H NMR (500 MH Z , CDCl 3 ): δ (ppm) = 4.33 (s, 8H), 1.94 (s, 24H). 13 Synthesis of Tetra-Arm Star PS (2). A dried 250 mL Schlenk flask was charged with 1 (1.52 g, 2.07 mmol), CuBr (0.29 g, 1.99 mmol), and CuBr 2 (0.02 g, 0.10 mmol).…”

“…The advances of controlled polymerization methods and chemistry have enabled polymer researchers to develop polymers of more complicated topologies than the usual linear polymers such as star-like, , comb-like, ,, dendrimer, and cyclic polymers − over the past decades. The researches of cyclic and multicyclic polymers are vigorously pursued because they have unique properties due to more compact topology and the absence of chain ends. − For example, the molecular topological constraints such as internal cross-links and physical knots in complex cyclic structures could influence the glass transition temperature and other physical properties. − Tezuka and co-worker synthesized different topological multicyclic poly­(THF)­s, including fused, , spiro, and bridged forms, with the introduction of intriguing synthetic techniques based on living polymerization as well as self-assembly protocols (electrostatic self-assembly and covalent fixation). Various topologically appealing multicyclic polymers including sun-shaped, , tadpole-shaped, − 8-shaped, , manacle-shaped, paddle-shaped polymers, and spiro form multicyclic polymer are also prepared through controlled radical polymerization or anionic polymerization.…”

Densely Arrayed Cage-Shaped Polymer Topologies Synthesized via Cyclopolymerization of Star-Shaped Macromonomers

“…Approach (ii) may be applied to the construction of cage -GPs by grafting a separately prepared cage-shaped macromolecule onto a reactive polymer backbone. This is probably feasible because some researchers have reported the synthesis of GPs possessing monocyclic side chains ( c -GPs) by the grafting onto method. ,− However, the necessity of preparing cage-shaped macromolecules containing a reactive functional group is a major hurdle in the way of realizing this approach. Furthermore, this strategy inherently produces poorly defined cage -GPs because the quantitative grafting of bulky polymeric chains is challenging.…”