Synthesis of Sequence-Specific Polymers with Amide Side Chains via Regio-/Stereoselective Ring-Opening Metathesis Polymerization of 3-Substituted cis-Cyclooctene

Abstract

Highly regio-/stereoregular (trans-head-to-tail) polymers with amide side chains on every eighth backbone carbon were successfully synthesized by ring-opening metathesis polymerization (ROMP) of 3-substituted cis-cyclooctene (3RCOE) using Grubbs second-generation catalyst (G2). Regioregular linear ethylene–acrylamide copolymers were also prepared via hydrogenation of the obtained poly­(3RCOE)­s. The thermal properties and solubility of the obtained polymers were strongly influenced by the presence of amide hydrogen in the side chains, the presence of unsaturated bonds in the carbon backbone, and the side chain density. The presence of amide hydrogen in the side chains resulted in the formation of crystalline polymers and the lack of solubility of these polymers in common organic solvents. In contrast, the absence of amide hydrogen in the side chains led to the formation of amorphous polymers exhibiting good solubility in common organic solvents, and decreasing values of T g were observed for amorphous polymers as a result of the saturation of double bonds in the backbone via hydrogenation.

Ring-Opening Metathesis Polymerization of δ-Pinene: Well-Defined Polyolefins from Pine Sap

“…For all PδP samples, highly resolved signals with clear splitting patterns were observed within the 1 H NMR spectra and indicate a well-defined microstructure (Figure ). Asymmetric cycloalkenes with a significant steric difference on one side of the olefin have been shown to propagate in a highly regioregular fashion through ROMP. − The clear doublet-of-doublets seen for the olefin protons of each PδP sample is expanded in a 1 H– 1 H correlated NMR spectrum (COSY) (CDCl 3 , 25 °C) of ID 10 (Table ) in Figure D. Here we note that this is a representative example reflecting nearly identical outcomes observed for all polymers.…”

Periodically Functionalized Linear Polyethylene with Tertiary Amino Groups via Regioselective Ring-Opening Metathesis Polymerization

“…Monomers of 4DR-CPE were prepared directly from commercially available 3-cyclopentene-1-carboxylic acid. The corresponding carboxylic acids for 3DR-COE and 3DR-CHE were prepared from COE and CHE, respectively, according to the literature . All the synthesized monomers were purified by fractional vacuum distillation and were isolated in good yield (4DR-CPE: up to 77%, 3DR-CHE: up to 68%, 3DR-COE: up to 72%; see the Supporting Information for details).…”

“…The methodology for producing polymeric materials with precisely controlled chemical structures is indispensable not only for industry but also for academia. For example, sophisticated analysis to clarify the fundamental structure–property relationships, followed by theoretical verification/demonstration, requires model samples with well-controlled chemical structures. − A systematic comparison of the changes in polymer properties that result from precise modifications in the polymer chemical structure, for example, the addition of a methylene unit and control of the regularities, would make it possible to elucidate the mechanism. − Considering this background, ring-opening metathesis polymerization (ROMP) is one of the most effective methods to accomplish the precision control of polymer chemical structures, especially olefin-based polymers. , In particular, ethylene-vinyl copolymers, which are one of the simplest polymer structures having linear alkyl main chains with functional groups, with controlled density and/or periodicity of functional groups, can be prepared by using functionalized monocyclic cycloolefins as the monomers and subjecting the resulting polymers to chemical hydrogenation. − These readily accessible, well-defined model polymers have been utilized for fundamental structure–property studies. − …”

Ring-Opening Metathesis Polymerization of 1,1-Disubstituted 1-Methylcyclopropenes

“…We hypothesized that stable five-membered chelation of Ru by the carbonyl oxygen atom from ring-opened 1 may have inhibited its propagation because we have previously isolated such a stable chelated complex from ring-opened 1-phenyl-1-methyl carboxylate CPE adduct to G3 . Interestingly, the groups of Hillmyer and Tanaka have reported on the ROMP of 3-substituted cyclooctenes containing ester or amide substituents, which did not inhibit homopropagation but yielded highly regio- and stereoregular poly­(3-substituted cyclooctene)­s. − The observed difference in metathesis reactivity between 3-substituted cyclooctene and CPE 1 , both having an allylic carbonyl substituent, may be attributed to 1 having two substituents at the allylic position, resulting in stronger chelation due to the Thorpe–Ingold effect.…”