Thermo-responsive polymers with aggregation induced emission

Self-assembled Fluorescent Nanoparticles with Tunable LCST Behavior in Water

The development of stimuli-responsive fluorescent materials in water based on organic molecule has drawn significant interest. Herein, we designed and synthesized an amphiphilic molecule M containing a fixed tetraphenylethylene moiety (FTPE) as hydrophobic part and tri(ethylene glycol) (TEG) chains as hydrophilic part. Notably, the FTPE moiety is aggregation-induced emission (AIE) active, while the TEG chains are thermo-responsive. M can self-assemble into fluorescent nanoparticles (NPs) in water, which showed lower critical solution temperature (LCST) behavior. Moreover, its clouding point can be reversibly tuned upon the concentration variation. Interestingly, the NPs can be acted as a fluorescence thermometer in aqueous media owing to their unique AIE and LCST behaviors. Our work herein not only provides an integration strategy to construct stimuli-responsive fluorescent materials but also shows great potential in biological applications including bioimaging and biosensors.

Aggregation-Induced Emission Boosting the Study of Polymer Science

The past one hundred years witness the great development of polymer science. The advancement of polymer science is closely related with the developing of characterization techniques and methods, from viscometry in molecular weight determination to advanced techniques including differential scanning calorimetry, nuclear magnetic resonance and scanning electron microscopy. However, these techniques are normally constrained to tedious sample preparation, high cost, harsh experimental condition, or ex-situ characterization. Fluorescence technology has the merits of high sensitivity and direct visualization. Contrary to conventional aggregation-causing quenching fluorophores, those dyes with aggregation-induced emission characteristic show high emission efficiency in aggregate states. Based on the restriction of intramolecular motions for AIE properties, the AIE materials are very sensitive to the surrounding microenvironments owing to the twisted propeller-like structures and therefore reveal great potentials in polymer's study. The AIE concept has been successfully used in polymer's study and provides us a deeper understanding on polymer structure and properties. In this review, the applications of AIEgens in polymer science for visualizing polymerization, glass transition, dissolution, crystallization, gelation, self-assembly, phase separation, cracking and self-healing were exemplified and summarized. Lastly, the challenges and perspectives in the study of polymer science using AIEgens are addressed. This article is protected by copyright. All rights reserved.

Fluorescent and stimuli-responsive performance of polymer composites filled with tetraphenylethene derivatives

In this study, a series of tetraphenylethene (TPE) derivatives with 3-butenloxy moieties were synthesized. The developed TPE with different number of substituent groups showed controlled aggregation-induced emission performance and variable...

Stimuli-responsive electrospun nanofibers based on PNVCL-PVAc copolymer in biomedical applications

Poly(N-vinylcaprolactam) (PNVCL) is a suitable alternative for biomedical applications due to its biocompatibility, biodegradability, non-toxicity, and showing phase transition at the human body temperature range. The purpose of this study was to synthesize a high molecular weight PNVCL-PVAc thermo-responsive copolymer with broad mass distribution suitable for electrospun nanofiber fabrication. The chemical structure of the synthesized materials was detected by FTIR and ¹HNMR spectroscopies. N-Vinyl caprolactam/vinyl acetate copolymers (159,680 molecular weight (g/mol) and 2.51 PDI) were synthesized by radical polymerization. The phase transition temperature of N-vinyl caprolactam/vinyl acetate copolymer was determined by conducting a contact angle test at various temperatures (25, 26, 28, and 30 [Formula: see text]). The biocompatibility of the nanofibers was also evaluated, and both qualitative and quantitative results showed that the growth and proliferation of 929L mouse fibroblast cells increased to 80% within 48 h. These results revealed that the synthesized nanofibers were biocompatible and not cytotoxic. The results confirmed that the synthesized copolymers have good characteristics for biomedical applications.