Preparation of Highly Uniform Polyurea Microspheres through Precipitation Polymerization and Their Characterization

Abstract

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.

Highly Uniform and Porous Polyurea Microspheres: Clean and Easy Preparation by Interface Polymerization, Palladium Incorporation, and High Catalytic Performance for Dye Degradation

“…Because the reactivity of TDI toward amines is much higher than toward water (Delebecq et al, 2013; Han et al, 2014; Jiang et al, 2017), there occurs the step-growth polymerization of TDI with the in-situ formed amines, leading to PU. Through this step-growth polymerization via water, we have prepared highly uniform PU microspheres by precipitation polymerization of isopherone diisocyanate (IPDI) in binary mixtures of water-acetone (Jiang et al, 2012) and water-acetonitrile (Jiang et al, 2016, 2017) as well as in a ternary mixture of water-acetone-DMF (Wei et al, 2019). However, with IPDI replaced by TDI, it was impossible to prepare microspheres by the same process; Granular PU with irregular form and size were always obtained, owing to the chemical structure of TDI, leading to a PU consisted of only carbamic units and aromatic rings.…”

Fluorescent linear polyurea based on toluene diisocyanate: Easy preparation, broad emission and potential applications

“…As supplementary information, it is to point out that polyurea is insoluble in common organic solvents, such as hexane, toluene, THF, acetone, pyridine and acetonitrile [64]. Among a dozen of solvents tested, the highest TPU concentration one can make is about 3 mg/mL in acetic acid and in m-cresol, which renders the comparison of the solvent effect on TPU emission difficult.…”

Controllable fluorescenceviatuning them-substituents of added aromatic molecules in a pyrene derivative-decorated porous skeleton

“…We considered that this dramatic phenomenon implied that the sample was dissolved in mcresol. 22,23 To further understand this phenomenon, the IR spectra of the PyCOOH-decorated PPUM in the absence and presence of m-cresol were performed (Fig. S9 †).…”

“…As a promising 3-D porous host skeleton, the porous polyurea microsphere (PPUM) is of great importance because it can be widely used in the host-guest system. Although several approaches were devoted to achieve the high production efficiency for the preparation of polyurea microspheres, [18][19][20][21][22][23][24] the syntheses and applications of the PPUM with uniform pores have been less investigated. Recently, a new crosslinked PPUM with the potential application for water treatment were successfully prepared by adding the triethylenetetramine (TETA) as a crosslinking agent and monodisperse SiO 2 particles as porogen via facile one-step precipitation polymerization.…”