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This work reports a facile and versatile ring-opening metathesis polymerization of three- and four-armed star-shaped poly(epsilon-caprolactone) (PCL) macromonomers bearing a norbornenyl group at each chain end using Grubbs' third-generation catalyst under diluted condition to obtain graft polymers (GPs) comprising densely arrayed three- and four-armed cage-shaped grafted PCLs (GPCLs) with narrow dispersity (1.19-1.35) and a controllable number of cage repeating units up to 40 (molecular weight: similar to 320 000 g mol(-1)). The GPCLs were characterized using nuclear magnetic resonance spectroscopy, size exclusion chromatography, and matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry. The cyclopolymerization proceeded via repetitive rapid intramolecular reactions to form cage-shaped units followed by slow intermolecular propagation. This synthesis was applicable to star-shaped poly(L-lactide), poly(trimethylene carbonate), and poly(ethylene glycol). Investigating the structure-property relationships regarding crystallization behavior, hydrodynamic diameter, and viscosity revealed that cage-shaped topological side chains reduced the chain dimensions and mobility compared to their linear and cyclic counterparts.

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 producespiro-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 desiredspiro-type topological polymers with a controllable number of ring units and molecular weight while retaining narrow dispersity (& x189; < 1.1). This effective strategy marks an advancement in the development of functionalized materials composed of specific three-dimensional nanostructures. Intramolecular ring-opening metathesis oligomerisation is a useful method for constructing multicyclic polymer cages. Here, it is applied to the synthesis of spirocyclic polymers with figure-8, trefoil, and quatrefoil structures with low polydispersity.

Cage-shaped polymers, or macromolecular cages, are of great interest as the macromolecular analogues of molecular cages because of their various potential applications in supramolecular chemistry and materials science. However, the systematic synthesis of macromolecular cages remains a great challenge. Herein, we describe a robust and versatile synthetic strategy for macromolecular cages with defined arm numbers and sizes based on the intramolecular consecutive cyclization of highly reactive norbornene groups attached to each end of the arms of a star-shaped polymer precursor. The cyclizations of three-, four-, six-, and eight-armed star-shaped poly(epsilon-caprolactone)s (PCLs) bearing a norbornenyl group at each arm terminus were effected with Grubbs' third generation catalyst at high dilution. H-1 NMR, SEC, and MALDI-TOF MS analyses revealed that the reaction proceeded to produce the desired macromolecular cages with sufficient purity. The molecular sizes of the macromolecular cages were controlled by simply changing the molecular weight of the star-shaped polymer precursors. Systematic investigation of the structure-property relationships confirmed that the macromolecular cages adopt a much more compact conformation, in both the solution and bulk states, as compared to their linear and star-shaped counterparts. This synthetic approach marks a significant advance in the synthesis of complex macromolecular architectures and provides a platform for novel applications using cage-shaped molecules with polymer frameworks.

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 third-generation 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 CH2Cl2) to give multicyclic polymers that feature cyclic PLLA repeating units on the polynorbornene bac...

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.