Synthesis Of High Molecular Weight Poly Research Articles

Catalyst-free synthesis of high-molecular weight poly(alkylene oxalate)s

In this work, a catalyst-free protocol, “volatility-assisted competitive transesterification polymerization”, was proposed to synthesize poly(alkylene oxalate)s with short reaction times.

New possibilities for the synthesis of high-molecular weight poly(2,5(6)-benzimidazole) and studies of its solutions in DMSO-based complex organic solvent

New possibilities for the synthesis of high-molecular weight poly(2,5(6)-benzimidazole) (ABPBI) based on a new monomer, 3,4-diaminobenzoic acid monophosphate, in polyphosphoric acid medium at high monomer concentration under stirring and on a Teflon® surface without stirring are investigated. New complex solvent for ABPBI is found. This solvent is based on dimethyl sulfoxide, methanol, and potassium hydroxide. For the first time, molecular weight values are obtained by dynamic light scattering and viscometry in complex solvent. In addition, Kuhn segment values are estimated. Maximal molecular mass MDη value reaches 94 kDa. The values of macromolecular equilibrium rigidity A are estimated as 4.4–5.7 nm according to translational diffusion coefficient and 3.3 nm according to intrinsic viscosity measurements.

Synthesis of high-molecular weight poly(1,1-dimethyl-1-silapentene) by olefin metathesis polymerization in the presence of Grubbs catalysts

Heterochain polycarbosilanes are well-known materials possessed important properties. Some of their applications, such as gas separation membranes, require polymers with high molecular weight that provide good film-forming and mechanical properties. In this research, the synthesis of poly(1,1-dimethyl-1-silapentene) via the ring-opening metathesis polymerization (ROMP) of 1,1-dimethyl-1-silacyclopentene and the acyclic dienes metathesis (ADMET) of diallyldimethylsilane mediated by Ru-carbene Grubbs complexes 1st - 3rd generations as well as Hoveyda-Grubbs 2nd generation catalyst were studied for the first time. High molecular weight poly(1,1-dimethyl-1-silapentene) was synthesized by ROMP of 1,1-dimethyl-1-silacyclopentene. Varying the type and loading catalyst, temperature and monomer concentration, we obtained poly(1,1-dimethyl-1-silapentene) with Mw = 100–143 kDa, which is significantly higher (5–7 times) than that reached previously by olefin metathesis polymerization. The activities of 1,1-dimethyl-1-silacyclopentene and cyclopentene in ROMP were compared using 1H NMR monitoring the conversion of their double bonds. The ADMET polymerization of diallyldimethylsilane led to oligomers with the average polymerization degree not exceeded 4.4.

Living Anionic Polymerization in Continuous Flow: Facilitated Synthesis of High-Molecular Weight Poly(2-vinylpyridine) and Polystyrene

We describe the living anionic polymerization of 2-vinylpyridine (2VP) and styrene (S) in continuous flow, comparing two micromixing devices with different mixing principles. The use of a continuous flow setup reduces the experimental effort for living anionic polymerizations significantly, compared to a conventional batch system. By adjusting the ratio of the flow rates of the monomer and initiator solutions a variety of different molecular weights can be rapidly synthesized within several minutes, using one setup. Additionally, a comparison of the influence of the two different mixing devices—an interdigital micromixer (SIMM-V2) leading to laminar mixing and a tangential four-way jet mixing device leading to a turbulent mixing pattern—has been achieved. Both setups allow living anionic polymerization in polar solvents at room temperature with full monomer conversion within seconds and yield polymers with narrowly distributed molecular weights. A maximum Mn of approximately 149,000 g mol–1 (PS-9, PDI = 1.04) for PS and 96,000 g mol–1 for P2VP (P2VP-15, PDI = 1.05) was obtained. Clearly, the turbulent four-way jet mixing device led to lower polydispersity than the laminar mixing device. All polymers were characterized by 1H NMR spectroscopy and size exclusion chromatography (SEC).

Synthesis of High-Molecular Weight Poly(vinyl alcohol) of Various Tactic Contents through Photo-Emulsion Copolymerization of Vinyl Acetate and Vinyl Pivalate

Photo-emulsion copolymerizations of vinyl acetate (VAc) and vinyl pivalate (VP) were carried out without initiator at 0°C, and copolymers giving high molecular weight poly(vinyl alcohol) (PVA) with various tacticities were obtained. The tacticities could be controlled between 22.3–12.8% for the isotactic triad and 27.7–38.3% for the syndiotactic triad by varying feed monomer composition.