Hydrophilic aromatic polyurethane
(HAPU) microspheres were prepared
through dispersion polymerization of a rosin-based polyurethane dispersion
with C=C and styrene (St). The effects of the monomer ratio
(i.e., waterborne rosin-based aromatic polyurethane (WRPU) to St),
dispersant level, and reaction temperature on the properties of the
microspheres were investigated; the effects of pH and adsorption temperature
on the adsorption capacity of Orange II were also studied. The microspheres
were characterized using Fourier transform infrared spectroscopy,
energy-dispersive spectrometry, thermogravimetric analysis, laser
particle size analysis, and scanning electron microscopy. The results
showed that HAPU microspheres have been successfully synthesized and
the produced microspheres exhibited good thermal stability and monodispersion.
The optimum reaction conditions for the preparation of the microspheres
were determined as a monomer ratio (
m
WRPU
/
m
St
) of 6:4 with 8 wt % poly(vinyl pyrrolidine)
(on the basis of the mixed monomer) at 80 °C for 8 h. Under these
conditions, the average particle size of the synthetic microspheres
was 120 nm and the particle size distribution index was 0.442. The
microspheres’ adsorption capacity for Orange II reached 17.53
mg·g
–1
when the solid–liquid ratio was
1 g·L
–1
, with an initial concentration of 100
mg·L
–1
at pH 5, and the adsorption was conducted
at 313 K for 3 h.
A simple and efficient procedure for the synthesis of amides directly from aldehydes and amines catalyzed by heteropolyanion-based ionic liquids under solvent-free conditions has been reported. The practical protocol was found to tolerate a wide range of substrates with different functional groups. Moderate to excellent yields, solvent-free media, and operational simplicity are the main highlights. The proposed dual-catalysis mechanistic pathway was briefly investigated. Furthermore, the heteropolyanion-based ionic liquids were easily reusable for this oxidative amidation.
Preparation of polymer microspheres from naturally occurring resource is a challenge. Here, a rosin-based polyol (RAG) was used to prepare polyurethane resin (RPU) firstly, and then act as both self-assembled precursor and emulsifier, rosin based polyurethane microspheres (RPUMs) were prepared. In the process of self-emulsification, the RPU formed vesicles by self-assembly. The outer shell of the vesicle consisted of hydrophilic segments, while the inner shell contained the hydrophobic phase. After cross-linking the RPU and removal of the solvent in the core, the porous-hollow microspheres with pH-sensitive were obtained. The microspheres were characterized by optical microscope (OM), scanning electron microscopy (SEM) and transmission electron microscope (TEM). The effect of type and amount of the hydrophilic chain extender, and solvent on the morphology, particle size and distribution, and buffer volume of the microspheres were determined. The best conditions for synthetic RPUMs were as follows: n NCO /n OH = 1, n RAG :n 1-(2-hydroxyethyl) piperazine = 4:6, with azodiisobutyronitrile level of 1.0 wt.%, based on reactive monomers, mixing speed of both emulsification and polymerization at 400 r•min -1 , the RPUMs synthesized had porous-hollow structure with a buffer volume of 1.6 mL.
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