Preparation of uniform poly(urea-siloxane) microspheres through precipitation polymerization

A novel type of highly uniform polymer microspheres, poly(urea-siloxane) (PUSs) was prepared through the precipitation polymerization of 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane (APTMDS) with isophorone diisocyanate (IPDI) in H 2 O-acetone mixed solvent. No additives such as surfactant and initiator were used. The effects of monomer ratio, H 2 O/acetone ratio, and monomer concentration on the yields and morphologies of the PUSs were investigated. Results indicated that PUS sizes can be regulated from 2.14 μm to 7.11 μm by varying the monomer ratio, monomer concentration and H 2 O/acetone ratio. Hydrogen bonds between polyurea units, polyurea and APTMDS moieties endowed the materials with good elasticity. The structures and morphologies of the materials were characterized by FT-IR, NMR, and SEM, and the thermal properties were characterized by TGA and DSC analyses. Preparation of PUSs through precipitation polymerization.