Synthesis of Miktoarm Branched Conjugated Copolymers by ROMPing In and Out

Abstract

Architecture represents an underutilized yet promising control element in polymer design due to the challenging synthesis of compositionally varied branched copolymers. We report the one-pot synthesis of miktoarm branched polymers by ring-opening metathesis polymerization. In this work, we graft to and from telechelic poly(3-hexylthiophene), which is end-capped by oxime click chemistry, using various norbornene monomers. The self-assembly of the resulting miktoarm H-shaped conjugated polymers is studied in solution and in the solid state. A dual stimuli-responsive miktoarm polymer is prepared which displays pH-switchable lower critical solution temperature and fluorescence.

Synthesis of Soluble Star-Shaped Polymers via In and Out Approach by Ring-Opening Metathesis Polymerization (ROMP) of Norbornene: Factors Affecting the Synthesis

“…Table 2 summarizes the results for the preparation of the star ROMP polymers by Method 2 under a high CL/Mo ratio (CL/Mo = 20). The results also showed that the Mn values in the resultant ROMP polymers increased over the reaction time in the core formation (2nd step, runs [26][27][28][29][30][31][34][35][36][37], and the PDI values became low when the ROMPs were conducted under diluted conditions (Mw/Mn = 1.58-2.22, runs 34-37). However, the resultant polymers still possessed bimodal molecular weight distributions (runs [34][35][36][37].…”

“…Star-shaped polymers consisting of linear arms connected at a central branched core are one of the simplest nonlinear polymers, and study for the precise synthesis by living polymerization technique attracts considerable attention [1][2][3][4][5][6][7]. Synthesis by adopting ring-opening metathesis polymerization (ROMP) [8][9][10][11][12][13][14][15][16] has been employed by sequential addition of monomers/cross linkers (CLs) [12,[17][18][19][20][21][22][23][24][25][26][27][28][29][30], and the resultant polymers (soluble in organic solvent, such as toluene, chloroform, dichloromethane, etc.) were applied as fluorescent materials [19], supported catalysts [20], and as controlled release and drug delivery systems [24,26,27].…”

Tailored silyl ether monomers enable backbone-degradable polynorbornene-based linear, bottlebrush and star copolymers through ROMP

“…Given its mild-conditions, living nature, and exceptional functional group tolerance, ROMP of norbornene-based compounds has been widely used to generate functional materials for applications including resin technologies, biomedicine, catalysis, and sensing. [1][2][3][4][5][6][7] In addition, "graft-through" ROMP of norbornene-based macromonomers (MMs) that carry drug molecules, imaging agents, or diverse polymer sidechains has enabled rapid access to advanced polymer architectures for combination drug delivery, molecular imaging, and selfassembly. [8][9][10][11][12][13][14][15][16] Nevertheless, the lack of facile degradability of polynorbornene-based polymers is a key limitation (Figure 1a).…”

Brush-First and ROMP-Out with Functional (Macro)monomers: Method Development, Structural Investigations, and Applications of an Expanded Brush-Arm Star Polymer Platform

“…18,19 Others subsequently showed that addition of small-molecule norbornene-based monomers to living star polymers prepared by arm-first ROMP enables the growth of new arms from the core, thus providing a new handle for tuning the star polymer functionality. 20–23 Such “in−out” processes have been demonstrated using other living polymerization techniques (e.g., ATRP 24–30 ) as well. Nonetheless, in the context of ROMP, these examples have invariably used small molecule monomers rather than MMs for the ROMP-in and ROMP-out steps.…”