A facile route to preparation of uniform polymer microspheres by quiescent polymerization with reactor standing still without any stirring

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

“…It is well-known that isocyanate (NCO) is highly reactive toward water, turning itself into amine by release of CO 2 . The in-situ formed amine groups copolymerize quickly with NCO groups, leading to PU formation (Leventis et al, 2010; Jiang et al, 2012, 2017; Li et al, 2013; Weigold et al, 2013; Han et al, 2016). Obviously, this process of PU synthesis is advantageous because the reactions involve only isocyanate monomer and water; it is a more cost effective and environment friendly approach than the classic synthesis of PU, because it replaces expensive amines with water, and in general it proceeds readily at ambient temperature.…”

“…Obviously, this process of PU synthesis is advantageous because the reactions involve only isocyanate monomer and water; it is a more cost effective and environment friendly approach than the classic synthesis of PU, because it replaces expensive amines with water, and in general it proceeds readily at ambient temperature. Through this process, two types of PU materials of different morphologies have been prepared, i.e., solid microspheres without porous structure (Jiang et al, 2012, 2017), and porous PU without regular form or shape (Leventis et al, 2010; Li et al, 2013, 2015a; Weigold et al, 2013; Han et al, 2014, 2016). It is easy to conceive that solid microspheres are of low specific surface area, and their use as support for enzyme and transition metal is not suitable because the amount of immobilized reagent on their surface are limited, or inaccessible as catalytic active site if incorporated in the microspheres; whereas for porous materials with irregular forms, it makes their recovery difficult due to their irregularity combined with their size difference, particularly for the very small ones.…”

“…It is therefore highly interesting to prepare porous and uniform polymer microspheres as the support for transition-metal-based catalysts and enzyme immobilization (Wu et al, 2012; Petkovich and Stein, 2013). Up to date, PU microspheres were prepared only with isophorone diisocyanate (IPDI) through precipitation polymerization (Jiang et al, 2012, 2017); with toluene diisocyanate (TDI), porous PU of irregular form was always obtained because of the chain rigidity of the resulting PU (Han et al, 2014; Li et al, 2015a).…”

Preparation of Thermoresponsive Polymer Nanogels of Oligo(Ethylene Glycol) Diacrylate-Methacrylic Acid and Their Property Characterization

“…Though the polymer formed was not soluble in water, they must be highly hydrophilic knowing that they are mainly consisted of ethoxylate and methacrylic acid. Taking this into account, it is conceivable that the polymer would precipitate out in a later stage of the polymerization, as was observed that the clear solution became turbid around 30 min after the initiation, a much longer time than in conventional precipitation polymerization [ 32 , 33 ]. In addition, the monomer concentration was very low (0.2 wt%), and the polymer formed, P(OEGDA-MAA), was crosslinked.…”

Preparation of uniform and porous polyurea microspheres of large size through interfacial polymerization of toluene diisocyanate in water solution of ethylene diamine

“…A broad size distribution was observed due to, likely, severe aggregation between the microspheres and/or the droplets, owing to the absence of a well-formed hard polymer shell at start of the polymerization. Based on this observation, all experiments were run under quiescent condition [11], i.e. without any stirring or shaking.…”