Unanticipated Strong Blue Photoluminescence from Fully Biobased Aliphatic Hyperbranched Polyesters

Abstract

Nonconventional fluorescent polymers without π-aromatic structure have attracted extensive interest in recent years. Hyperbranched polyesters are generally known because of their industrial applications; however, the luminescent properties of the polyester has not been reported. Herein, we synthesized a series of fully biobased aliphatic hyperbranched polyesters via a one-pot A2 + B3 esterification reaction. Intriguingly, the resultant hyperbranched polyesters carrying no conventional fluorescent units exhibited unexpected bright blue fluorescence under 365 nm UV light. It was found that the fluorescence intensity was enhanced with increasing solution concentrations and molecular weights of the polyesters. Moreover, the results suggested that the luminescence of polyesters could be controlled by solvents and metal ions. In particular, the fluorescence of the polyesters was extremely sensitive to Fe3+. More interesting is that the fluorescence of the polyesters showed an aggregation-induced enhanced emission in the mixture system. Notably, the resulting polyesters displayed a remarkably enhanced quantum yield (16.75%) as compared with that of other types of these polymers. Preliminary results demonstrate that clustering of the carbonyl groups is responsible for the unusual fluorescence in the aliphatic hyperbranched polyesters, namely, clustering-induced emission (CIE). This study provides a novel perspective for the design of biobased luminescent materials to new application areas.

Unprecedented Multicolor Photoluminescence from Hyperbranched Poly(amino ester)s

“…Compared with the conventional AIEgens, AIEgens carrying no phenyl rings have more advantages in the field of biological sensing and imaging due to their low toxicity and outstanding biocompatibility . Many non‐conjugated polymers with aggregation‐induced emission (AIE) characteristics have been reported, such as poly(amidoamine), poly(amino ester), poly(ethylenimine), polysiloxanes, polyurea, polycarbonate, and Polyacrylonitrile . These polymers generally emit blue fluorescence under particular excitation owing to the presence of non‐conventional chromophores such as aliphatic tertiary amine, carbonyl, ester and amide.…”

Unprecedented strong blue photoluminescence from hyperbranched polycarbonate: From its fluorescence mechanism to applications

“…As to its emission mechanism, it still remains under dispute. There are a few reports suggest that the emission of these polymers is related to its morphology . Therefore, we utilize TEM to find the relationships between the morphology and fluorescence intensity of the HBPC.…”

LCST‐Type Hyperbranched Poly(oligo(ethylene glycol) with Thermo‐ and CO2‐Responsive Backbone

“…Over the past few dacades, hyperbranched polymers (HBPs) have been actively explored both in fundamental researches and material design due to their convenient one‐pot synthesis procedures, compact globule‐like shapes, and appealing properties including good solubility, low viscosity, and abundant chain‐end functional groups . Therefore, they have gained great interests in application areas like coatings, additives, catalysts, drug delivery, etc . Recently, HBPs with a soluble–insoluble phase transition above their lower critical solution temperature (LCST) are increasingly reported for biomedical and biotechnological uses, these thermoresponsive HBPs combine the advantages of thermoresponsive polymers and HBPs together.…”

“…[1][2][3][4][5] Therefore, they have gained great interests in application areas like coatings, additives, catalysts, drug delivery, etc. [6][7][8][9] Recently, HBPs with a soluble-insoluble phase transition above their lower critical solution temperature (LCST) are increasingly reported for biomedical and biotechnological uses, [10,11] these thermoresponsive HBPs combine the advantages of thermoresponsive polymers and HBPs together. In general, strategies to design and prepare thermoresponsive HBPs lie in two categories: one is the modification of HBPs or dendrimers with temperature-responsive functional groups or oligomer segments; [11][12][13][14][15][16] the other one is to prepare backbone-based thermoresponsive HBPs by introducing thermoresponsive functionalities into the backbone of hyperbranched polymers via proton transfer polymerization, Michael addition polymerization, ring-opening polymerization, etc.…”