Multiblock Copolymers by Thiol Addition Across Norbornene

Abstract

Multiblock copolymers, composed of different combinations and number of blocks, offer appreciable opportunities for new advanced materials. However, exploring this parameter space using traditional block copolymer synthetic techniques, such as living polymerization of sequential blocks, is time-consuming and requires stringent conditions. Using thiol addition across norbornene chemistry, we demonstrate a simple synthetic approach to multiblock copolymers that produces either random or alternating architectures, depending on the choice of reactants. Past reports have highlighted the challenges associated with using thiol−ene chemistry for polymer−polymer conjugation; however, using norbornene as the "ene" yielded multiblock copolymers at least four or five blocks. Preparation of new multiblock copolymers containing two or three block chemistries highlights the versatility of this new approach. These materials were thermally stable and showed microphase separation according to characterization by DSC, SAXS, and AFM. This chemical platform offers a facile and efficient route to exploring the many possibilities of multiblock copolymers.

Monte Carlo Simulations of the Phase Separation of a Copolymer Blend in a Thin Film

“…This lamellar-in-lamellar structure is very similar to those found in multiblock copolymer self-assembly, [21][22][23][24][25][26][27][28][29] while the alternating and block copolymers in our copolymer blend system are much easier to be synthesized than that of asymmetric multiblock copolymers. [30][31][32] In this contribution, to explore the influence of system parameters such as segment distribution and segregation strength on phase separation, we design a series of polymer Monte Carlo simulations were carried out to study the phase separation of a copolymer blend comprising an alternating copolymer and/or block copolymer in a thin film, and a phase diagram was constructed with a series of composed recipes. The effects of composition and segregation strength on phase separation were discussed in detail.…”

Wide Bicontinuous Compositional Windows from Co-Networks Made with Telechelic Macromonomers

“…23,26 Often, multiblock copolymer synthesis requires a series of rigorous living polymerizations 27,28,29 although recent investigations using end-linking strategies have simplified multiblock synthesis. 23,26,30 In contrast to equilibrium structures, numerous groups have investigated methods to trap non-equilibrium bicontinuous morphologies formed as a result of spinodal decomposition. 31,32,33,34 Demixing is typically induced through solvent, 35 temperature, 36 or polymerization 37,38 induced phase separation, and coarsening of the bicontinuous morphology is then kinetically arrested using several routes including vitrification, 32 chemical cross-linking, 39 or jamming/gelation of nanoparticles.…”

Click and Multicomponent Reactions Work Together for Polymer Chemistry

“…Tew and coworkers reported a successful synthesis of multiblock copolymers via dithiol small linkers to be reacted with α,ω-dinorbornene-end functional polymers in THF using photoinitiated thiol-ene technique. [19] On the other hand, Bowman group very recently reported that efficient thiol-ene click reactions for polymer-polymer conjugation strictly depend on a proper initiator and end group selection. [20] They achieved ≈91% efficiency in the conjugation of a thiol-terminated poly(ethylene glycol) (PEG) to a norbornene-terminated PEG in water using photoinitiated thiol-ene reactions.…”

“…In this regard, there are a few exceptions reported in literature. Tew and coworkers reported a successful synthesis of multiblock copolymers via dithiol small linkers to be reacted with α,ω‐dinorbornene‐end functional polymers in THF using photoinitiated thiol‐ene technique . On the other hand, Bowman group very recently reported that efficient thiol‐ene click reactions for polymer–polymer conjugation strictly depend on a proper initiator and end group selection .…”