Synthesis of Highly Monodisperse Surface-Functional Microspheres by Photoinitiated RAFT Dispersion Polymerization Using Macro-RAFT Agents

Abstract

Highly monodisperse PMMA microspheres have been synthesized by photoinitiated RAFT dispersion polymerization in the presence of a Macro-RAFT agent and a small molecular RAFT agent. A particle yield of over 90% was achieved within 3 h under UV irradiation at room temperature. The Macro-RAFT agent acts as a stabilizer and stabilizes the particles via formation of block copolymers in situ, and XPS analysis shows that about 29.9% of the particle surface was covered by the stabilizer. Various surface functional microspheres were prepared by using four kinds of Macro-RAFT agents, including poly(methoxy poly(ethylene glycol) acrylate)-based trithiocarbonate (P(mPEGA)-TTC), poly(methoxy poly(ethylene glycol) acrylate-co-acrylic acid)-based trithiocarbonate (P(mPEGA-co-AA)-TTC), poly(acrylic acid)-based trithiocarbonate (PAA-TTC), and poly(methoxy poly(ethylene glycol) acrylate-co-4-vinylpyridine)-based trithiocarbonate (P(mPEGA-co-4VP)-TTC). Ag/PMMA nanocomposite spheres were prepared using the P(mPEGA-co-AA)-TTC stabilized microspheres. The PAA-TTC stabilized microspheres showed pH sensitivity. The colloidal stability of the particles prepared by this photoinitiated RAFT dispersion polymerization was also investigated.

Fast and facile one-step synthesis of monodisperse thermo-responsive core–shell microspheres and applications

“…27,37 This may be attributed to an insufficient number of RAFT groups which leads to poor control during the nucleation stage. 27,28 To address this problem, a certain amount of small molecular RAFT agents was added into the reaction mixture to compensate for the low RAFT agent concentration. As shown in Fig.…”

“…The result suggests that even though the high UV intensity induces a high reaction rate, the addition of small molecular RAFT agents can prolong the nucleation stage to an appropriate time scale, which is one of the features of photoinitiated RAFT dispersion polymerization. 27,28 . Fig.…”

“…27 One of the attractive features of this approach is that Macro-RAFT agents can be directly used as stabilizers without consideration of the sensitive nucleation stage. 28 Thus, it is expected that monodisperse thermo-responsive microspheres can be synthesized by photoinitiated RAFT dispersion polymerization through the use of a thermo-responsive Macro-RAFT as the stabilizer.…”

“…However, the reaction rate was greatly slowed down when the RAFT process was introduced to the system; reaction time of 4h was normally needed for achieving high conversions. 27,28 In this case, the large-scale synthesis with a continuous process becomes difficult.…”

Atom transfer radical polymerization to fabricate monodisperse poly[glycidyl methacrylate- co -poly (ethylene glycol) methacrylate] microspheres and its application for protein affinity purification

“…In particular, narrowly dispersed and cross-linked polymer microspheres have been synthesized. Polyethylene (PE), polystyrene (PS) and poly(methyl methacrylate) (PMMA) microspheres are popular types of polymer microspheres because of their capability to expedite procedures such as cell sorting and immune-precipitation [9][10][11][12]. These polymer beads are generally hydrophobic and often require additional surfactant to ensure ease of handling.…”