Preparation, characterization, and chiral recognition of optically active polymers containing pendent chiral units via reversible addition‐fragmentation chain transfer polymerization

Abstract

Optically active polymers bearing chiral units at the side chain were prepared via reversible addition‐fragmentation chain transfer (RAFT) polymerization in the presence of 2,2′‐azobisisobutyronitrile (AIBN)/benzyl dithiobenzoate (BDB), using a synthesized 6‐O‐p‐vinylbenzyl‐1,2:3,4‐Di‐O‐isopropylidene‐D‐galactopyranose (VBPG) as the monomer. The experimental results suggested that the polymerization of the monomer proceeded in a living fashion, providing chiral group polymers with narrow molecular weight distributions. The optically active nature of the obtained poly (6‐O‐p‐vinylbenzyl‐1,2:3,4‐Di‐O‐isopropylidene‐D‐galactopyranose) (PVBPG) was studied by investigating the dependence of specific rotation on the molecular weight of PVBPG and the concentration of PVBPG in tetrahydrofuran (THF). The results showed the specific rotation of PVBPG increased greatly with the decrease of the concentration of the PVBPG homopolymer. In addition, the effect of block copolymers of PVBPG on the optically active nature was also investigated by preparing a series of diblock copolymers of poly(methyl methacrylate) (PMMA)‐b‐PVBPG, polystyrene (PS)‐b‐PVBPG, and poly(methyl acrylate) (PMA)‐b‐PVBPG. It was found that both the homopolymer and the diblock copolymers possessed specific rotations. Finally, the ability of chiral recognition of the PVBPG homopolymer was investigated via an enantiomer‐selective adsorption experiment. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3788–3797, 2007

Alternating Placement of d‐ and l‐Alanine Moieties in the Polymer Side‐Chains

“…Such kind of observations were also reported by Wang et al. for the optically active polymer poly(6‐ O ‐ p ‐vinylbenzyl‐1,2:3,4‐di‐ O ‐isopropylidene‐ d ‐galactopyranose) . Generally, the chiroptical properties of artificial polymers depend on several other factors such as the presence of stereoregular secondary structures and the chirality of the repeating units .…”

Mechanism study and molecular design in controlled/“living” radical polymerization

“…Optical active polymers were synthesized by using chiral initiators [99,100] or chiral monomers [100,101]. The polymerization of the studied systems was in a controlled way though the polydispersity index of the obtained optical active polymers was slightly larger than that in normal cases.…”

Synthesis of Glycopolymer Architectures by Reversible-Deactivation Radical Polymerization

“…Wang et al [203] studied the optical activity of homopolymers and block copolymers obtained from the RAFT polymerization of protected glycomonomer M51. Homopolymerizations of M51 were carried out in in the presence of R12 (toluene, 90 °C, 50 h) and showed a hybrid evolution of molar mass with conversion, with M n reaching a plateau at ~40% conversion (Entry 240, Table 3).…”

“…Al-Bagoury et al [177] reported the RAFT polymerization of isopropylidene protected D-glucofuranose methacrylate M13 and D-fructopyranose methacrylate M45 in mini-emulsion. Polymerizations were conducted at 70 °C in a mixture of hexadecane/H 2 O/SDS/NaHCO 3 using three different dithiobenzoate-type RAFT agents (R9, R10 and R11; Entry 190,[201][202][203][204] Table 3). Big deviations of molar masses with respect to their theoretical values were observed in all cases and the best results were obtained using R9 (Đ  1.25, M n /M n,th < 2.7).…”