Investigating the Reactivity of a Novel Methacrylic Transmer in Solution RAFT-SCVP and Its Impact on the Structure of the Resulting Hyperbranched Polymers

Abstract

A novel methacrylic-based R-transmer, named 2-(methacryloyloxy)­ethyl 4-cyano-4-(((propylthio)­carbonothioyl)­thio)­pentanoate, was synthesized, and its reactivity (propagation versus reversible chain transfer) in reversible addition–fragmentation chain transfer self-condensing vinyl polymerization (RAFT-SCVP) with methyl methacrylate (MMA) was studied to apprehend its impact on hyperbranched polymers (HBP) structure. The resulting HBP were characterized by nuclear magnetic resonance (NMR) spectroscopy, size exclusion chromatography (SEC) and differential scanning calorimetry (DSC) to determine, respectively, their composition and degree of branching (DB), number average molecular weight (Mn ) and dispersity (Đ), and glass transition temperature (T g). Homopolymers of methacrylic-based R-transmer and copolymers with MMA were considered to study the reactivity of the methacrylic-based R-transmer with different initial molar ratios [MMA]0/[R-transmer]0 through kinetic studies and its consequences on HBP macromolecular characteristics and thermal properties. By varying the [MMA]0/[R-transmer]0 ratio from 1:1 to 100:1, HBP with increasing Mn (from 6,400 to 14,900 g mol–1) and T g values (from 36.1 to 87.9 °C), decreasing Đ values (from 4.07 to 1.71) and DB values (from 0.30 to 0.03) were obtained.

Chain Architecture as an Orthogonal Parameter to Tune Morphologies of Polymer Assemblies: Efficient Synthesis and Self-Assembly of Linear-Branched Block Copolymers via RAFT Dispersion Polymerization

“…This is because the methacryloyl group of CEPEMA can copolymerize with DMAEMA during the RAFT solution polymerization, which undergoes a mixed mechanism of step-growth (condensation of the RAFT group with double bonds) and chain growth (polymerization of double bonds) (Scheme S1). According to work reported by Despres et al, the high-molecular-weight shoulder should be the branched polymer structure with less branching points while the low-molecular-weight peak should be the branched polymer structure with more branching points. As the linear chain length of PDMAEMA n -P­(DMAEMA m - co -CEPEMA)-CEPA ( n + m = 60) increases, the molecular weight distribution of the polymer became narrower due to the decreased fraction of the branched part.…”

“…Figure a shows the 1 H NMR spectra of CEPA, HEMA, and CEPEMA, confirming the successful synthesis of this CTM with high purity. It should be noted that trithiocarbonate-based CTMs with a methacryloyl R-group and a thioalkyl Z-group have rarely been reported. − Very recently, Despres et al reported a detailed investigation on solution RAFT-SCVP using a CTM with a similar structure. We then conducted a kinetic study of RAFT solution polymerization of CEPEMA and 2-(dimethylamino)­ethyl methacrylate (DMAEMA) in ethanol with a [CEPEMA]/[DMAEMA] ratio of 1/1 (Figure S1).…”

Aqueous RAFT Dispersion Polymerization Mediated by an ω,ω-Macromolecular Chain Transfer Monomer: An Efficient Approach for Amphiphilic Branched Block Copolymers and the Assemblies

“…With increasing [CEPEMA]/[HPMA] ratio, the SEC trace shifted to a lower molecular weight. This can be attributed to the increased number of polymers with more branching points as the [CEPEMA]/[HPMA] ratio was increased, leading to the observed decrease in the SEC-characterized molecular weight …”