Complex Polymer Architectures Using Ring-Opening Metathesis Polymerization: Synthesis, Applications, and Practical Considerations

Abstract

Nature shows us that complex molecular architectures lead to unique material properties, and these observations have driven polymer scientists to synthesize complex architectures in an effort to discover how topology influences properties in synthetic polymers. In this Perspective, we discuss a variety of complex architectures synthesized using ringopening metathesis polymerization (ROMP), including multiblock linear polymers, bottlebrush homopolymers and (multi)block copolymers, dendronized polymers, star polymers, and polymer−biomolecule conjugates. Traditional and recently developed synthetic methods, including polymerization-induced self-assembly, copolymerization to create gradient structures, and engineering approaches to making complex topologies using ROMP, are also reviewed. In this context, we highlight emerging applications stemming from these materials, including drug delivery vehicles, nanoscale constructs, and components in light refraction or energy storage, among others. Finally, we conclude with an indepth discussion on practical considerations in ROMP that enable the highest level of control when synthesizing complex polymer topologies from sterically demanding or otherwise challenging (macro)monomers. Our hope is that this Perspective will guide scientists synthesizing complex polymer architectures toward new and innovative materials with the potential for unique properties and applications.

Radical–radical coupling effects in the direct-growth grafting-through synthesis of bottlebrush polymers using RAFT and ROMP

“…Bisnorbornenyl species can also form even when radical polymerizations are not employed in the MM synthesis; for example, the diol impurity present in commercial monofunctionalized polyethylene glycol (PEG) can affect the synthesis of bottlebrush polymers. 13 Thus, synthetic methods to reduce the presence of bisnorbornenyl species in MMs are needed to achieve well-defined bottlebrush polymers, which are under investigation for the synthesis of complex polymer topologies [14][15][16][17][18] and applications including biomedicine, [19][20][21][22][23][24][25] electronic and transport materials, 26,27 elastomers, 6,[28][29][30][31][32] photonic crystals, [33][34][35][36][37] and nanoporous materials. [38][39][40][41] Two approaches are typically used to synthesize MMs monofunctionalized with a norbornene.…”

Poly(vinyl alcohol) Molecular Bottlebrushes Nucleate Ice

“…Next, a series of high-density PVA bottlebrush polymers were prepared using ROMP “grafting-through” approach using a norbornene-end poly­(vinyl acetate) macromonomer (NB-PVAc), Figure A. Exo -5-norbornene-2-methylamine was synthesized in this case (Figures S8–S15; see the Synthetic Procedures section in the Supporting Information), as it was demonstrated by Matson and co-workers that the choice of anchor group dramatically affects overall ROMP propagation rates with norbornene anhydride-based macromonomers leading to poorer chain extensions and conversions when targeting high M w bottlebrushes. , …”

“…Exo-5-norbornene-2-methylamine was synthesized in this case (Figures S8−S15; see the Synthetic Procedures section in the Supporting Information), as it was demonstrated by Matson and co-workers that the choice of anchor group dramatically affects overall ROMP propagation rates with norbornene anhydride-based macromonomers leading to poorer chain extensions and conversions when targeting high M w bottlebrushes. 42,43 A norbornyl xanthate chain-transfer agent (NB-CTA) of 2-(ethoxycarbonothioylthio)-2-methylpropanoic acid exo-5-norbornene-2-methylamide was synthesized and used to prepare an NB-PVAc 208 macromonomer via photo-initiated RAFT/ MADIX polymerization (NB-PVAc 208 , Conv. = 67%, M n,SEC RI = 17.9 kDa, Đ M = 1.4).…”

Controllable synthesis and structural design of novel all-organic polymers toward high energy storage dielectrics

“…The precise preparation of functional polymers has high requirements on the synthetic method used. From the perspective of chemistry and materials, ROMP, as a polymerization method with controllable activity, fast reaction speed and high efficiency, has become a very powerful and versatile approach for constructing functional polymer materials with different topological structures like CRP ( Barbey et al, 2009 ; Jennings et al, 2016 ; Wang et al, 2016 ; Zoppe et al, 2017 ; Corrigan et al, 2020 ; Messina et al, 2020 ; Blosch et al, 2022b ).…”