Norbornene‐functionalized PEO‐b‐PCL: A versatile platform for mikto‐arm star, umbrella‐like, and comb‐like graft copolymers

Abstract

Well-defined in-chain norbornene-functionalized poly(ethylene oxide)-b-poly(E-caprolactone) copolymers (NB-PEOb-PCL) were synthesized from a dual clickable containing both hydroxyl-and alkyne-reactive groups, namely heterofunctional norbornene 3-exo-(2-exo-(hydroxymethyl)norborn-5-enyl)methyl hexynoate. A range of NB-PEO-b-PCL copolymers were obtained using a combination of orthogonal organocatalyzed ring-opening polymerization (ROP) and click copper-catalyzed azide-alkyne cycloaddition (CuAAC). Ring-opening metathesis polymerization (ROMP) of NB-PEO-b-PCL macromonomers using rutheniumbased Grubbs' catalysts provides comb-like and umbrella-like graft copolymers bearing both PEO and PCL grafts on each monomer unit. Mikto-arm star A 2 B 2 copolymers were obtained through a new strategy based on thiol-norbornene photoinitiated click chemistry between 1,3-propanedithiol and NB-PEO-b-PCL. The results demonstrate that in-chain NB-PEO-b-PCL copolymers can be used as a platform to prepare mikto-arm star, umbrella-, and comb-like graft copolymers.

How does the type of counterion influence the polymerization rate and thermal properties of tailored choline‐based linear‐ and star‐shaped poly(ionic liquid)s PILs?

“…The higher dispersity indices observed at very high conversions might be a result of chain‐breaking reaction, which in the case of ChMA/Cl − might be a result of transesterification due to the presence of methanol in the reaction mixture. Similar observations for that monomer have been demonstrated previously by Armes, Makuska, and Neugebauer . However, it should be pointed out that the amount of that side reaction decreases with an increasing the steric hindrance effect.…”

“…However, the full conversion of ChMA/NTf 2 − was not reached. It should be stressed that similar observations have been reported for imidazolium‐based or trimethlammonium‐based ILs. The kinetic plot of ln([M] 0 /[M] t ) versus time [see Fig.…”

“…As documented above, there are numerous CRP methods enabling the production of well‐defined macromolecules with varied topologies, including linear and nonlinear (grafted, star‐shaped, hyperbranched). Similarly, there are many reports in the literature concerning the synthesis of linear PILs by CRP methods .…”

Synthesis and Self‐Assembly of Mixed‐Graft Block Copolymers

“…Whereas Cheng et al. reduced steric hindrance effects by including a spacer chain in the design of the BMM, work by the Fontaine group illustrated the limitations of ROMP when the BMMs are too crowded at the norbornene junction . When PEO and PCL side chains were directly linked to the norbornene without a spacer (Scheme b), the conversion of the BMM ( M n =4.0 kDa) in ROMP was very limited (45 % for a backbone DP of 50).…”

Grubbs’ and Schrock’s Catalysts, Ring Opening Metathesis Polymerization and Molecular Brushes—Synthesis, Characterization, Properties and Applications

“…Then, G3 was employed to polymerize PEO macromonomers ( M n ~ 3000) with very good control (1.04 < I < 1.27) for DPs up to 400 [ 51 ]. After 2015, there are a few papers where G1 and G2 have been used to polymerize PEO macromonomers [ 13 , 52 , 53 , 54 ] and a comparison between G1 , G2, G3 and G3’ was made by some researchers [ 53 , 54 ]. In general, G3 (and G3’ ) provided the best results and the seeding technique [ 54 ] was proven useful.…”