In contrast to conventional fluorescent polymers featured by large conjugation structures, a new class of fluorescent polymers without any conjugations is gaining great interest in immerging applications beyond the possibility to achieve by the conjugated polymers. Poly(ethylene glycol) (PEG), widely used in biomedical fields for a long time owing to its nontoxicity and nonimmunogenicity, is found to be fluorescence emissive in the solid state and in aqueous solution, though deemed as not fluorescent in numerous reports. Through systematic study under different conditions, the emission is ascribed to the cluster formation of its chains; thereby the blue-shift of the emission with the excitation wavelength was interpreted through the Forster resonance energy transfer. The clusterization was ascertained through size measurements, Fourier transform infrared spectroscopy, NMR analyses, and the dependence on temperature, pH, and nonsolvent presence. Tested in the presence of competitive metal ions, selective emission quenching by Fe 3+ and Cr 6+ was observed. PEG was used as a sensor for the detection of Cr 6+ , Fe 3+ , and H 2 O 2 , outperforming most of the reported sensors alike. Its uses for data encryption and cell imaging were also presented. This work provides therefore a novel face of PEG with great potential in a variety of emerging applications, in particular, as sensors in the biomedical area.

• Toluene diisocyanate (TDI) based polyurea (TPU) is prepared by TDI reaction with H 2 O. • TPU shows strong fluorescent emission as solid powder and in its solution. • The emission in UV region is intrinsic due to its phenyl and the adjacent urea group. • The emission in visible zone is owing to the formation of molecule clusters. • Paper strip dipped in TPU solution is used for easy detections of Fe 3+ and H 2 O 2 .

Porous polyurea is synthesized by reacting toluene diisocyanate with water in a water–acetone binary solvent. Materials characterization led to the likely conformations of the polymer chains owing to presence of intensive H-bonding.

No abstract

No abstract

Uniform polymer microspheres with neat surface are of high interests. Precipitation polymerization of vinylic monomers remains a very limited process owing to very low monomer concentration allowed. Here, a fully novel protocol for the production of uniform polymeric microspheres is presented. Using one single monomer, isophorone diisocyanate, highly monodisperse polyurea microspheres were achieved with very high yield in a very short time period via precipitation polymerization in water-acetone mixed solvent. Results demonstrated that the ratio of water-acetone and polymerization temperature played important roles in the process. The size of the microspheres was readily adjustable by varying monomer concentration, water/acetone ratio or polymerization temperature. V C 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 49: [4492][4493][4494][4495][4496][4497] 2011

Uniform polyurea (PU) microspheres were prepared through precipitation polymerization of isophorone diisocyanate (IPDI) in water–acetone mixed solvent, under mechanical oscillation and quiescent conditions. Higher yield with better uniformity for the microspheres was achieved under the quiescent process. The preparation was therefore optimized for the quiescent process. The maximal IPDI loading reached 11.0 wt % with the yield of the microspheres of 88.5%. With acetone replaced by acetonitrile, this yield was increased further to 93.5% combined with also a higher IPDI loading of 15.0 wt % at the same time. The chemical structure of PU was studied using nuclear magnetic resonance. PU microspheres, insoluble in most of organic solvents tested, were dissolved in m-cresol at 30 °C and in acetic acid at 66 °C. These results showed that the PU microspheres consisted of only linear polymers. This work provides therefore a simple and promising protocol for large-scale production of highly uniform polymer microspheres through precipitation polymerization without any additives.

No abstract