Synthesis of star polymers using ultrasound‐induced RAFT polymerization

Abstract

An alternative method to efficiently synthesize Core‐Crosslinked Star polymers (arm‐first approach) is described in this work. The star polymers are produced utilizing a two‐step, one‐pot Sono‐RAFT process. N,N′‐dimethylacrylamide (DMA) is used to prepare the arms, whereas N,N′‐methylenebis(acrylamide) (MAA) is employed as the crosslinking agent. The reactions were conducted in an aqueous medium at room temperature. Using the sono‐RAFT approach, polymerization under different applied powers, crosslinker to arm ratios, and degrees of polymerization were investigated to determine the optimal reaction conditions for synthesizing star polymers. By altering the applied power, the reaction time can be decreased by half. Using a triblock arm, a CCS polymer was produced, and the resulting polymer demonstrated a very high arm‐to‐star conversion.

Branched Polymers: Synthesis and Application

“…Star polymers possess a high functional group density and superior stimulation reactivity after modification. Based on these advantages, lots of works have been done to synthesize star polymers with well-defined structure, and the common synthesis routes can be divided into three categories: “core-first”, ,,, “arm-first”, ,,, and “grafting to”. ,− In the following, the advantages and disadvantages of each synthesis strategy are summarized, which help to make the right choice when synthesizing star polymers with different properties.…”

“…And the branching degree of the polymers obtained from step-growth polymerization is dependent on the multifunctional monomers. In the synthesis of branched polymers, conventional radical polymerization sometimes leads to gelation, while living radical polymerization has shown satisfactory performance in some cases. − In recent years, great efforts to synthesize well-defined branched polymers by living polymerization such as reversible addition–fragmentation chain transfer polymerization (RAFT), ,− atom transfer radical polymerization (ATRP), ,, ring-opening polymerization (ROP), ,, ring-opening metathesis polymerization (ROMP), ,− nitroxide-mediated polymerization (NMP), − iodine transfer polymerization (ITP), − living cationic polymerization (LCP), , and living anionic polymerization (LAP) − have been made. RAFT polymerization regulates the radical concentration using thiocarbonate as chain transfer agent to control the reversible chain transfer of macromolecular chains.…”