Partitioning effect of nitrogen catalyst into polymerizing particles on dispersion reversible chain transfer catalyzed polymerization (dispersion RTCP) of methyl methacrylate in supercritical carbon dioxide and organic solvents

Abstract

Reversible chain transfer catalyzed polymerization (RTCP) in dispersion polymerization system (dispersion RTCP) of methyl methacrylate (MMA) was performed with N‐iodosuccimide (NIS) as a nitrogen catalyst in supercritical carbon dioxide (scCO2). The solubility of NIS in scCO2 can be controlled by tuning the pressure, and this led to promote NIS partitioning into polymerizing particles. As a result, the molecular weight distribution control was successfully improved by decreasing the NIS solubility in the medium by tuning the scCO2 at a low pressure of 20 MPa. On the other hand, at the same NIS concentration, a solution RTCP of MMA in toluene as a homogeneous polymerization system did not proceed with a controlled/living manner. The importance of NIS partitioning into the polymerizing particles was also confirmed in hexane as well as scCO2 medium. From these results, it was clarified that the NIS catalyst partitioning into the polymerizing particles as main polymerization loci is a key factor to control the molecular weight distribution in the dispersion RTCP of MMA in scCO2. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 613–620

Synthesis of Block Copolymer Particles by One-Pot, Two-Step Dispersion Reversible Chain Transfer Catalyzed Polymerization (Dispersion RTCP) in Supercritical Carbon Dioxide

“…Moreover, as described a little in the Introduction, the dispersity index should be decreased by decreasing the pressure of reactor (>7.4 MPa), which decreases the solubility of NIS in scCO 2 , resulting in an increase in the partition of NIS into polymerizing particles. 44 ■ CONCLUSIONS PMMA-b-PS particles were successfully synthesized by the one-pot, two-step dispersion RTCP (rirst step: MMA, at 30 MPa for 6 h at 80 °C; second step: styrene, at 50 MPa for 24 h at 100 °C). After the two-step polymerization, the total conversion attained 60%, but product was obtained as a powder after venting CO 2 .…”

“…If an appropriate chain transfer agent and catalyst proposed by them are chosen in this RTCP system, the dispersity index should be decreased. Moreover, as described a little in the Introduction, the dispersity index should be decreased by decreasing the pressure of reactor (>7.4 MPa), which decreases the solubility of NIS in scCO 2 , resulting in an increase in the partition of NIS into polymerizing particles …”

“…43 It was clarified that the partitioning of the nitrogen catalyst into the main polymerization loci (polymerizing particles) is important for the successful dispersion RTCP in scCO 2 system. 44 In this study, the synthesis of PMMA−PS block copolymer (PMMA-b-PS) particles will be demonstrated by one-pot, twostep dispersion RTCP with nitrogen catalyst in scCO 2 because the polymer architecture design is also important characteristics of the CLRP. This will open one possible way to obtain easily block copolymer powder (after venting CO 2 ) in the environmentally friendly medium.…”

“…Furthermore, dispersion RTCP of methyl methacrylate (MMA) with N -iodosuccinimide as a nitrogen catalyst was also demonstrated in scCO 2 . It was clarified that the partitioning of the nitrogen catalyst into the main polymerization loci (polymerizing particles) is important for the successful dispersion RTCP in scCO 2 system …”