Linear Copolymers of Ethylene and Polar Vinyl Monomers via Olefin Metathesis−Hydrogenation:  Synthesis, Characterization, and Comparison to Branched Analogues

Abstract

Materials structurally equivalent to copolymers of ethylene and <10 mol % of vinyl alcohol, vinyl acetate, methyl acrylate, tert-butyl acrylate, and acrylic acid were synthesized via ruthenium-catalyzed olefin metathesis copolymerization followed by polymer hydrogenation. These polymers differ from previous metathesisderived linear polyethylene analogues in that they do not have precise sequence distributions, and therefore, they serve as superior models for chain-addition functional polyethylenes. The ester group-substituted polymers display rapid decreases in melting temperature and heat of fusion with increasing comonomer contents irrespective of the identity of the functional group, consistent with these groups being equally excluded from the crystal lattice. The alcohol-substituted polymers, however, show higher melting temperatures and a weaker property dependence on comonomer content as compared to the other polymers. Thus, the behavior of alkyl branch-free functionalized polyethylenes is consistent with the large body of work involving the effects of functional substituents on polyethylenes containing alkyl branches.

Synthesis and utility of ethylene (meth)acrylate copolymers prepared by a tandem ring‐opening polymerization hydrogenation strategy

“…13,16 Synthesis of Methyl (Z)-Cyclooct-4-ene-1-Carboxylate (MEC) This known compound was prepared via a slightly different procedure from Wagener and coworkers and the spectral ARTICLE data were in accordance with literature data. 13 In a 1-L high pressure reactor (Series 4520 Bench Top Reactors, 1L, Parr Instrument Company), palladium (II) chloride (2.9 g, 16.3 mmol), triphenylphosphine (17 g, 64.8 mmol), anhydrous methanol (42 mL, 1038 mmol), 1,5-cyclooctadiene (COD, 200 mL, 1630 mmol) and toluene (100 mL) were placed. The reactor was sealed and then pressurized to 400 psig with carbon monoxide and then vented down to 30 psig.…”

“…The known monomer used in this study, tert-butyl (Z)-cyclooct-4-ene-1-carboxylate (BEC) was prepared according to a similar procedure reported by our group based on the work of Wagener and coworkers. 13,16 The homopolymerization of MMEC (or BEC) was performed in anhydrous chloroform using 0.025 mol% G2 at 50 8C (Scheme 2). Cis-4-octene was used as a chain transfer agent (CTA) to control the M n of the resulting polymers.…”

“…Interestingly, PEAA-12.5 shows a sharper melting transition than PEBA-12.5, presumably due to H-bonding between the carboxylic acids. 13 Thermogravimetric analysis (TGA) of the PEAAs and PEMMAs revealed temperatures corresponding to 5% mass loss (T d,5% ) from 285 to 414 8C under nitrogen (Table 1) indicative of reasonable thermal stability toward degradation that results in mass loss. Most of the PEBAs (except for the PEBA-0.3 with highest ethylene content) have lower T d,5% values than those of PEAAs, most likely due the loss of isobutylene groups when heated to high temperatures, which we will discuss in the next section.…”

“…[10][11][12] In the work described here we prepared two substituted cyclooctenes that gave statistical copolymers of ethylene and either methyl methacrylate or t-butyl acrylate/acrylic acid (closely following the work of Wagener and co-workers in the latter case). 13 and used without further purification unless noted otherwise. Cyclooctene (COE) was purchased from Acros Organics.…”

“…Polyethylene homopolymers for the control blend preparation were synthesized according to previously published procedure. 15 Molecular Characterization 1 H NMR and 13 C NMR spectra were recorded on Bruker AM-400, AV-500, AX-400, and Bruker HD-500 spectrometers using residual solvent peaks as internal standards; CDCl 3 , CF 3 COOD, and toluene-d 8 were used as the solvents.…”