Volume 53 Issue 8, August 2021

Recently, controlled/living supramolecular polymerization has been evolved by many research groups; however, the principles of monomer design remain elusive. In this focused review, I present a case study of a series of porphyrin-based monomers that we have investigated over the past 10 years. By systematically designing monomers, we have been able to gain deep insights into the mechanisms of controlled/living supramolecular polymerization, and we have even been able to apply the developed method to synthesize two-dimensional supramolecular nanosheets with controlled areas and aspect ratios.

Ferroelectric polymers, poly(vinylidene fluoride) (PVDF), and its copolymers have been exploited for various applications, including nonvolatile memories, energy harvesters, and piezoelectric/pyroelectric sensors. To achieve better performance in PVDF-based devices, crystallization manipulation and controllable nanostructure formation are unavoidable and are of crucial importance. For this review, recent exploitation of the control of PVDF ferroelectric polymer crystallization at the nanoscale was specifically examined and summarized to provide insight into the future development of ferroelectric polymer nanomaterials.

The polymerization of divalent acyl-1,2,4-triazoles and diols/bisphenols afforded a series of aromatic, semiaromatic, and aliphatic polyesters. Compared with polymerization by transesterification, this polymerization proceeded irreversibly at relatively low temperature (<100 °C) without a metal catalyst. The reactivities of acyl-1,2,4-triazoles were thus comparable to acyl chlorides. On the other hand, higher crystallinity and lager masses of acyl-1,2,4-triazole caused technical problems, particularly for the synthesis of polyarylates. Nevertheless, solution polymerization was effective to prepare polyacrylates, particularly which could not be synthesized by interfacial polymerization.

The confinement effect on the chain conformation and crystallization behavior of poly(ethylene oxide) (PEO) in electrospun nanofibers was investigated. The PEO chains in electrospun nanofibers were tightly packed and exhibited a zigzag conformation. Increasing the fiber diameter reduced the packing of polymer chains, resulting in increases in the melting temperature and crystallite size. Thermal treatment relaxed the stretched chains, which induced a change from the metastable zigzag conformation to a stable helical conformation. Additionally, the melting temperature, degree of crystallinity, and crystallite size increased with increasing annealing temperature.

Poly[oligo(2-ethyl-2-oxazoline) methacrylate] (P[O(Ox)_nMA]) was mixed into a thin film of poly(methyl methacrylate) (PMMA) to construct a bioinert polymer surface in water. Near-ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) revealed that P[O(Ox)_nMA] having nitrogen atoms in the side chains was segregated at the outermost region of the PMMA film in a water environment. The extent of the segregation was dependent on the architecture of P[O(Ox)_nMA] due to the entropic factor, and greater extent was better for the platelet adhesion and activation.

Polyelectrolytes (PEs) with high water uptake prepared from cellulose-type polysaccharides are promising because of their excellent biodegradability. In this work, utilizing a two-step selective oxidation process a new type dicarboxylate nanocrystalline cellulose (DCNC) PE was prepared. Carboxylate units were introduced at the C-2 and C-3 positions of a glucose moiety to ensure the presence of a large number of dissociable electrolytic ions. It was observed that the equilibrium water uptake capacity of the prepared DCNC was almost ten times greater than that of conventional C-6 functionalized monocarboxylated nanocrystalline cellulose.

A binder, poly(2-propenoic acid, 2-methyl-, 3-[(2-aminoethyl) amino]-2-hydroxypropyl ester) (P-HAEAPMA), is synthesized and applied to silicon/graphite anodes in lithium-ion batteries, which exhibits good electrochemical stability. After 305 cycles, a specific capacity of 485.0 mA h g⁻¹ and a capacity retention rate of 74.8% are achieved. Moreover, the discarded electrode with P-HAEAPMA binder can be reused just based on water because the P-HAEAPMA binder is easily soluble in water, and the electrochemical properties of the electrode with reused materials are slightly lower than those of the original electrode.

The microwave heating technique has been widely used in various organic and inorganic syntheses, and it has been reported that this technique provides the desired compounds quickly and easily. In this work, we applied microwave heating to synthesize redox-active organic nanoparticles consisting of hyperbranched viologen units. By the precise temperature control afforded by use of microwave irradiation, we succeeded in controlling the growth and termination reactions kinetically and preparing viologen nanoparticles in one-pot. We also demonstrated that the size of the nanoparticles can be controlled by varying the temperature program.

A novel thermoresponsive diblock copolymer of methyl poly (ethylene glycol)-b-poly (O-benzyl-L-threonine) was synthesized. The copolymer solutions exhibited gel-to-sol UCST transition behavior with temperature. The gel-to-sol transition was due to the disassembly of the initial β-sheet layered nanoassemblies that induced the transformation of self-organized morphology from nanosized fibrils to spherical aggregates.