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

Abstract

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 H2O-acetone mixed solvent. No additives such as surfactant and initiator were used. The effects of monomer ratios, H2O/acetone ratios, and monomer concentrations on the yields and morphologies of the PUSs were investigated. Results indicated that PUSs sizes can be regulated from 2.14 µm to 7.11 µm by varying monomer ratios, monomer concentrations and H2O/acetone ratios. Hydrogen bonds between polyurea units, polyurea and APTMDS moieties which were identified as the main effects of the products, 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.

Thermoreversible Supramolecular Networks from Poly(trimethylene Carbonate) Synthesized by Condensation with Triuret and Tetrauret

“…The resonances at 7.00 ppm group all labile protons from −NH− in urethane bonds (H c , H i , and H u ) and urea bonds (H r ). 46,47 The doublet resonances ranging from 5.86 to 5.74 ppm are assigned to −NH− protons in urea groups (H q ). 48,49 Resonances also appear between 5.47 and 5.57 ppm.…”

“…The resonances of glycerol protons are at 5.03 ppm ( H a ) and 3.65 ppm ( H b ). The resonances at 7.00 ppm group all labile protons from −NH– in urethane bonds ( H c , H i , and H u ) and urea bonds ( H r ). , The doublet resonances ranging from 5.86 to 5.74 ppm are assigned to −NH– protons in urea groups ( H q ). , Resonances also appear between 5.47 and 5.57 ppm. They might be due to the low hydrolysis of isocyanate groups in H 12 MDI by moisture brought by PTMC oligomers, generating additional alkyl amine functions .…”

Thermal Energy Storage Using Poly(ethylene glycol) Incorporated Hyperbranched Polyurethane as Solid–Solid Phase Change Material

“…The strong peak at δ 3.586 ppm and δ 70.46 ppm corresponds to a chemical shift of the −O–CH 2 –CH 2 –O– group of PEG. The peaks of alicyclic ring of IPDI are observed at δ 2.839, δ 1.655, δ 0.989, and δ 0.874 ppm in 1 H NMR, whereas it can be observed in the range of δ 23.21–44.66 ppm in 13 C NMR. , Because of the high molecular weight of PEG as compared to the other reactants and the formation of complex aggregates of peaks of interests, the degree of branching was not possible to determine for these hyperbranched polyurethanes from the 1 H NMR spectrum …”

Designer poly(urea-siloxane) microspheres with controlled modulus and size: Synthesis, morphology, and nanoscale stiffness by AFM

“…The spheres reported were rather large, with a size range of 580e620 mm, limiting their applications, for instance, as a microand nanofiller. An interesting approach was shown recently by Li and co-workers, who demonstrated that uniform disiloxane-urea spheres with diameters ranging from 2.14 to 7.11 mm can be obtained via a one-step precipitation polymerization procedure [20]. We believe that modification of these disiloxane-urea microspheres may lead to the manufacturing of novel heterogeneous materials with enhanced properties, e.g., polymer composites, where the above-mentioned characteristics of polyureas and PDMS, as well as properties of the matrix, can be synergistically combined and thus the physicochemical properties of the final material can be tuned.…”