Facilely Control Grafting Density and Side Chain Composition of Bottlebrush Polymer

Control over polymer architecture and composition is essential for disclosing structure-property relationships and developing high performance materials. Herein, a new method was successfully developed to synthesize bottlebrush polymer (BP) with controllable graft density and side chain composition by "grafting-from" strategy using in situ halogen exchange and reversible chain transfer catalyzed polymerization (RTCP). The main chain of the BP was firstly synthesized by the polymerization of methacrylates contained alkyl bromide as side group. Then, the alkyl bromine was quantitatively convert to alkyl iodide with sodium iodide (NaI) via in situ halogen exchange to efficient initiate the RTCP of methacrylates. By adjusting the input amount of NaI and monomers in sequence, BP named PBPEMA-g-PMMA/PBzMA/PPEGMEMA which contains three different kinds of polymer side chain including hydrophilic PPEGMEMA, hydrophobic PMMA and PBzMA was synthesized with narrow molecular weight distribution (M_w /M_n ≤ 1.36). The graft density and the chain length of each polymer side chain was well controlled by the addition of NaI in batches and following RTCP. Moreover, the obtained BP self-assembled into spherical vesicles in aqueous with hydrophilic coronal structure, core region and hydrophobic wall between the former two, which enables to wrap hydrophobic pyrene and hydrophilic Rhodamine 6G separately or simultaneously. This article is protected by copyright. All rights reserved.

Preparation of Biomolecule-Polymer Conjugates by Grafting-From Using ATRP, RAFT, or ROMP

Biomolecule-polymer conjugates are constructs that take advantage of the functional or otherwise beneficial traits inherent to biomolecules and combine them with synthetic polymers possessing specially tailored properties. The rapid development of novel biomolecule-polymer conjugates based on proteins, peptides, or nucleic acids has ushered in a variety of unique materials, which exhibit functional attributes including thermo-responsiveness, exceptional stability, and specialized specificity. Key to the synthesis of new biomolecule-polymer hybrids is the use of controlled polymerization techniques coupled with either grafting-from, grafting-to, or grafting-through methodology, each of which exhibit distinct advantages and/or disadvantages. In this review, we present recent progress in the development of biomolecule-polymer conjugates with a focus on works that have detailed the use of grafting-from methods employing ATRP, RAFT, or ROMP.

One-pot synthesis of glycyrrhetic acid polyglycosides based on grafting-from method using cyclic sulfite

Glycyrrhetic acid polyglycosides were synthesized in one-pot via cationic ring-opening condensation polymerization of cyclic sulfite (4) initiated by glycyrrhetic acid as an aglycon. Sulfite 4 worked as a practical monomer for the preparation of (1 → 2)-linked polysaccharide skeletons. The chemical stability of 4 was evaluated by the comparison of thermodynamic parameters with those of conventional epoxide (2). The grafting reaction of 4 from glycyrrhetic acid (5) was performed in the presence of TfOH and MS 3A in CH2Cl2 at room temperature. The polymerization degree was moderately controllable by the change of feed ratio of initiator.