Intramolecular consecutive cyclization was established as a versatile and robust strategy to synthesize macromolecular cages.

A novel synthesis of multicyclic polymers that feature ultradense arrays of cyclic polymer units has been developed by exploiting the cyclopolymerization of α,ω-norbornenyl end-functionalized macromonomers mediated by the Grubbs thirdgeneration catalyst (G3). Owing to the living polymerization nature, the number of cyclic repeating units in these multicyclic polymers was controlled to be between 1 and approximately 70 by varying the initial macromonomer-to-G3 ratio. The ring size was also tuned by choosing the molecular weight of the macromonomer; in this way we successfully prepared multicyclic polymers that possess cyclic repeating units composed of up to about 500 atoms, which by far exceeds those prepared to date by cyclopolymerization. Specifically, cyclopolymerizations of α,ω-norbornenyl end-functionalized poly(L-lactide)s (PLLAs) proceeded homogeneously under highly dilute conditions (∼0.1 mM in CH 2 Cl 2 ) to give multicyclic polymers that feature cyclic PLLA repeating units on the polynorbornene backbone. The cyclic product architectures were confirmed not only by structural characterization based on NMR, MALDI-TOF MS, and SEC analyses but also by comparing their glass transition temperatures, viscosities, and hydrodynamic radii with their acyclic counterparts. The cyclopolymerization strategy was applicable to a variety of α,ω-norbornenyl end-functionalized macromonomers, such as poly(ε-caprolactone), poly(ethylene glycol) (PEG), poly(tetrahydrofuran), and PLLA-b-PEG-b-PLLA. The successful statistical and block cyclocopolymerizations of the PLLA and PEG macromonomers gave amphiphilic multicyclic copolymers.

The development of precise folding techniques for synthetic polymer chains that replicate the unique structures and functions of biopolymers has long been a key challenge. In particular, spiro-type (i.e., 8-, trefoil-, and quatrefoil-shaped) polymer topologies remain challenging due to their inherent structural complexity. Herein, we establish a folding strategy to produce spiro-type multicyclic polymers via intramolecular ring-opening metathesis oligomerization of the norbornenyl groups attached at predetermined positions along a synthetic polymer precursor. This strategy provides easy access to the desired spiro-type topological polymers with a controllable number of ring units and molecular weight while retaining narrow dispersity (Ɖ < 1.1). This effective strategy marks an advancement in the development of functionalized materials composed of specific three-dimensional nanostructures.

We demonstrated a novel strategy for the preparation of light down-converter by combining rod-coil block copolymers with perovskite quantum dots (QDs) through electrospinning. Reports have shown that polymer deformability can be enhanced by incorporating a soft segment and controlled by varying the rod/coil ratio. Therefore, we first synthesized the rod-coil block copolymer through the click reaction of polyfluorene (PF) and poly(n-butyl acrylate) (PBA). Next, the CsPbBr3@PF8k-b-PBA12k composite fibers were fabricated by blending perovskite through electrospinning. Optical spectral evidence demonstrated the success of the strategy, as light down-converters were prepared through the controlled variance of QD/polymer ratios to achieve tunable color and stretchability. This result reveals the potential of using rod-coil block copolymers to fabricate color-tunable perovskite light down-converters.