Green Stereoregular Polymerization of Poly(methyl methacrylate)s Through Vesicular Catalysis

Abstract

Stereoselective polymerization can yield polymers with specific tacticity and properties, and it is an important topic throughout the polymer synthesis history. Herein, we report for the first time on a vesicular catalysis method to realize the green stereoregular polymerization of isotactic-rich poly(methyl methacrylate) (PMMA) in water and at ambient temperature and pressure, namely by conducting the polymerization of MMA monomers in the confined 5-10 nm thick hydrophobic layers of hyperbranched polymer vesicles. The isotactic degree of the as-prepared PMMAs increases from 12% to 40% with the decrease of vesicle size from 840 nm to 85 nm in hydrodynamic diameter (D h ) owing to the conformation confinement effect of MMA monomers inside the thin vesicle membranes through a curvature-dependent way. The present work has extended the scope of green chemistry, and it also represents a new application of polymer vesicles in stereoregular polymerization.

pH-Controlled Stereoregular Polymerization of Poly(methyl methacrylate) in Vesicle Membranes

“…Figure S16 shows the differential scanning calorimetry (DSC) curves of the obtained PMMAs, and the T g of each polymer sample is listed in Table 1. Similar to commercial PMMAs (T g = 127 °C), 33 T g of the PMMAs we obtained in DMSO was about 127 °C. According to the literature, T g of pure isotactic PMMA was about 45 °C.…”

“…Evidently, obvious peak shifts caused by the conformation confined effect were observed with the encapsulation time increasing from 1 to 10 h (Figure a). According to our previous study, the carbonyl band can be deconvoluted into two peaks at 1720 and 1700 cm –1 by Lorentzian functions (Figures b and S17–S19). The peak at 1720 cm –1 corresponded to the carbonyl group of free MMA, while the peak at 1700 cm –1 was assigned to the vibration and dipole couplings of carbonyl groups of confined MMA. − …”

“…Polymerization within the membranes did not destroy the vesicle structure as negligible morphological changes were observed after polymerization (Figure S12). Notably, a common radical polymerization method was used instead of photoinduced electron transfer−reversible addition−fragmentation chain transfer (PET-RAFT) polymerization as before 33 because fluorescein, which was involved in the PET-RAFT polymerization, deteriorated as the pH values changed, while BP was non-pH-responsive. Moreover, the generality of vesicular catalysis polymerization can be further explored by using the common radical polymerization.…”

“…Very recently, our group found that polymer vesicle membranes could serve as confined nanospaces to realize stereoselective green polymerization of PMMAs, a so-called vesicular catalysis process. The polymerization proceeded in water at ambient temperature and pressure and conformed to green chemistry . It represents a new application of polymer vesicles.…”

“…The polymerization proceeded in water at ambient temperature and pressure and conformed to green chemistry. 33 It represents a new application of polymer vesicles. However, in this previous study, a hyperbranched multiarm copolymer with a hyperbranched poly(3-ethyl-3oxetane-methanol) (HBPO) core and many polyethylene oxide (PEO) arms through two-step cationic ring-opening polymerizations was prepared.…”