Design of Graft Architectures via Simultaneous Kinetic Control of Cationic Vinyl-Addition Polymerization of Vinyl Ethers, Coordination Ring-Opening Polymerization of Cyclic Esters, and Merging at the Propagating Chain End

Abstract

Versatile graft architectures were synthesized in one shot via simultaneous controlled cationic vinyl-addition polymerization of vinyl ethers (VEs) and coordination ring-opening polymerization of cyclic esters (CEs). Graft copolymers were generated via independent propagation reactions and transient incorporation of a poly(CE) chain into the side chain of the poly(VE) propagating end via the exchange of alkoxy groups. In this mechanism, the grafting density and grafting length of a copolymer were designable by tuning the rates of each propagation reaction and the exchange reaction. As a result of a systematic investigation, the effects of polymerization conditions, such as the kinds and concentrations of monomers and catalysts, on the rate of each reaction were revealed and a design principle of various graft architectures was established. Notably, a copolymer with a remarkably high grafting density was obtained [max. 88% of poly(VE) side chains were substituted with poly(CE) chains] when a VE with an ethylenedioxy side chain was used with a titanium catalyst. The specific interaction of an ethylenedioxy unit and a titanium catalyst was key to the high grafting density.

Graft Copolymers of N-Isopropylacrylamide with Poly(d,l-lactide) or Poly(ε-caprolactone) Macromonomers: A Promising Class of Thermoresponsive Polymers with a Tunable LCST

“…Poly­( N -isopropylacrylamide) synthesized in the presence of DMP as a RAFT agent in 1,4-dioxane as a solvent is characterized by a close to theoretical number-average molar mass and low dispersity, confirming the reaction proceeding in a controlled fashion (Table ). Homopolymerizations of poly­( d , l -lactide) with methacrylate (PLA-MA600) and acrylate (PLA-A500) groups produce polymers with a significantly lower experimentally determined number-average molar mass than the theoretical one, which could be explained by the underestimation of the molar mass measured by conventional SEC for such brush-type polymers. − However, the polydispersities of polymers are rather low, especially those for polymers prepared from PLA-A500, indicating the certain control over polymerization in the case of homopolymerization of macromonomers (Table ).…”

Unzipping and scrambling reaction‐induced sequence control of copolymer chains via temperature changes during cationic ring‐opening copolymerization of cyclic acetals and cyclic esters

“…[28][29][30] ε-Heptanolactone (ε-HepL) was synthesized by Baeyer-Villiger oxidation according to previously reported procedures. 31,32 EtSO 3 H (Aldrich; 95%), PhSO 3 H (TCI; >98.0%), p-toluenesulfonic anhydride (Ts 2 O; Aldrich; 97%), trifluoromethanesulfonic acid (TfOH; Aldrich; >99.0%), bis(trifluoromethanesulfonyl)imide (Tf 2 NH; Wako; 98.0+%), and Ti(OBu) 4 (Alfa Aesar; 99+%) were used without further purification after preparing stock solutions in CH 2 Cl 2 . C 4 F 9 SO 3 H (TCI; >98.0%) and ptoluenesulfonic acid monohydrate (TsOHÁH 2 O; TCI; >98.0%) were used without further purification after preparing stock solutions in CH 2 Cl 2 (the acids were slightly insoluble).…”

Sequence Control from Mixtures: Switchable Polymerization Catalysis and Future Materials Applications

“…For example, 3-, 4- and 6-arm star poly­(ε-decalactone)-poly­( l -lactide) elastomers have higher Young’s moduli (3.7× for 6-arm) and stress at break (2× for 6-arm) than equivalent linear (2-arm) polymers. , These switchable catalytic polymerizations should also be amenable to the formation of graft polymers by exploiting postfunctionalization or protection/deprotection strategies to expose hydroxyl decorated backbones that can initiate polymer chain growth. Aoshima and co-workers recently provided a demonstration of a single catalyst simultaneously effective for cyclic ester ROP and cationic vinyl-ether polymerization to deliver branched materials …”

“…Aoshima and co-workers recently provided a demonstration of a single catalyst simultaneously effective for cyclic ester ROP and cationic vinyl-ether polymerization to deliver branched materials. 144 ■ HIGHER-ORDER BLOCK SEQUENCES AND MULTIBLOCKS Higher-order blocks and multiblock polymers may access a wider range of phase separated nanostructures and offer property improvements. 145−147 For example, ABC triblock polymers, featuring three immiscible blocks, may promote morphologies where chains bridge distinct hard domains rather than loop back into the same domain (Figure 9).…”