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Polyimine represents a rapidly emerging class of readily accessible and affordable covalent adaptable networks (CANs) that have been extensively studied in the past few years. While being highly malleable and recyclable, the pioneering polyimine materials are relatively soft and not suitable for certain applications that require high mechanical performance. Recent studies have demonstrated the possibility of significantly improving polyimine properties by varying its monomer building blocks, but such component variations are usually not straightforward and can be potentially challenging and costly. Herein, we report an in situ oxidation polymerization strategy for preparation of mechanically strong poly(imine-amide) (PIA) hybrid CANs from simple amine and aldehyde monomers. By converting a portion of reversible imine bonds into high-strength amide linkages in situ, the obtained hybrid materials exhibit gradually improved Young's modulus and ultimate tensile strength as the oxidation level increased. Meanwhile, the PIAs remain reprocessable and can be depolymerized into small molecules and oligomers similar as polyimine. This work demonstrates the great potential of the in situ transformation strategy as a new approach for development of various mechanically tunable CANs from the same starting building blocks. [ABSTRACT FROM AUTHOR]

In consideration of various advantages such as less harm, higher sensitivity, and deeper imaging depth, etc., AIE materials with longwave emission are attracting extensive attention in the fields of vascular visualization, organelle imaging, cells tracker, forensic detection, bioprobe and chemosensor, etc. In this work, a novel fluorescent (R)-PVHMA monomer with chirality and aggregation-induced emission enhancement (AEE) characteristics was acquired through enzymatic transesterification reaction basing on phenothiazine, and its [α]D25°C value was about −6.39° with a 3.08 eV bandgap calculated by the quantum calculations. Afterwards, a series of PEG-PVH1 and PEG-PVH2 copolymers with chirality feature were achieved through RAFT polymerization of the obtained (R)-PVHMA and PEGMA with various feed ratios. When the feed molar ratio of (R)-PVHMA increased from 21.5% to 29.6%, its actual molar fractions in the PEG-PVH1 and PEG-PVH2 copolymers accordingly increased from 18.1% to 25.7%. The molecular weight of PEG-PVH1 was about 2.2×104 with a narrow PDI, and their kinetics estimation showed a first-order quasilinear procedure. In aqueous solution, the amphiphilic copolymers PEG-PVH could self-assemble into about 100 nm nanoparticles. In a 90% water solution of H2O and THF mixture, the fluorescence intensity had the maximum value, and the emission wavelength presented at 580 and 630 nm. The investigation of cytotoxicity and cells uptake showed that PEG-PVH FONs performed outstanding biocompatibility and excellent cells absorption effects, which have great potential in bioimaging application. [ABSTRACT FROM AUTHOR]