Bulk and solution copolymerization of methyl methacrylate and vinyl acetate

Low Temperature, In Situ Polymerization of Vinyl Acetate in Silica Containing Emulsion Gels

Vinyl acetate (VAc) was polymerized to about 90% conversion in 9 h at 40°C from the colloidal microstructure of the VAc/fumed silica/cetyltrimethylammonium bromide (CTAB) system. The glass transition ( $T_g$ ) of poly(vinyl acetate) (PVAc) polymerized in these emulsion gels with silica was higher ( $T_g={41}^{°}\text{C}$ ) than those of PVAc made from bulk polymerization at 60°C ( $T_g={31}^{°}\text{C}$ ) and the weight average molar mass ( $M_w$ ) was also larger ( $M_w$ about 300 kg/mol) than those from bulk polymerization ( $M_w=125\text{kg}/\text{mol}$ ). Increased $M_w$ , $T_g$ , and lowered processing temperature for these composites could facilitate new applications for PVAc.

Thiol-Lactam Initiated Radical Polymerization (TLIRP): Scope and Application for the Surface Functionalization of Nanoparticles

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Controlled polymerization techniques make the possible fabrication of polymers with desired molecular weights, narrow dispersity, and tailor-making of advanced hybrid materials. Thiol- Lactam Initiated Radical Polymerization (TLIRP) was introduced in 2002 and developed during the last two decades. The thiol/lactam combination enables one to generate radicals that can initiate the polymerization of vinyl-based monomers. The study of the mechanism and kinetics of TLIRP revealed the characteristics of living polymerization for TLIRP. Moreover, TLIRP has been used successfully for the synthesis of homopolymers, block copolymers, and statistical copolymers with polydispersity below 2.0. Especially, TLIRP provides a very straightforward method for grafting polymer brushes on the surface of nanoparticles. We review herein the systems developed for TLIRP and their applications for macromolecular engineering, emphasizing the surface functionalization of nanoparticles via the grafting-from approach.

Highly reactive, liquid diacrylamides via synergistic combination of spatially arranged curing moieties

Six polymerizable N,N’-diacylamides containing spatially arranged N-acryl, N-allyl and/or N-alkyl groups were prepared via two-step syntheses and characterized by ¹H/¹³C NMR-spectra, refractive index (RI) and viscosity measurements. Photo DSC measurements on activated samples provided reactivity parameters ∆H_p, R_p,max and t_max, while FTIR spectra before and after curing elucidated the underlying polymerization mechanism. Mechanical testing of the obtained polymers exhibited gradual differences in network densities, depending on the intramolecular arrangement and number of functional groups. Overall, a general building principle for highly reactive, liquid diacrylamides via synergistic combination of optimally arranged functional groups could be identified. The highest possible level of intramolecular synergism was found for low viscous N,N'-diacryloyl-N,N'-diallyl-1,4-but-2-enediamine.

Investigation of free-radical copolymerization propagation kinetics of vinyl acetate and methyl methacrylate

The free-radical copolymerization propagation kinetics of vinyl acetate (VAc) and methyl methacrylate (MMA) at 50 degrees C were investigated through an experimental study combined with a computational analysis based on quantum chemistry. Copolymer composition data, obtained using pulsed laser polymerization followed by size exclusion chromatography (PLP-SEC) and proton nuclear magnetic resonance (NMR), were well represented by the terminal model using monomer reactivity ratios obtained with the computational approach (r(VAc) = 0.001 and r(MMA) = 27.9). Concerning the composition-averaged copolymerization propagation rate coefficient k(p,cop), the differences between the terminal model and the implicit penultimate unit effect (IPUE) model (s(MMA) = 0.544 and s(VAc) = 0.173) are small for VAc/MMA, with the terminal model sufficient to describe the experimental k(p,cop) data measured by PLP-SEC. Monomer and radical charge distributions determined computationally are used to explain the reactivity exhibited by the VAc/MMA system.

A comparison of electrospray-ionization and matrix-assisted laser desorption/ionization mass spectrometry with nuclear magnetic resonance spectroscopy for the characterization of synthetic copolymers

Electrospray ionization (ESI-MS) and matrix assisted laser desorption-ionization (MALDI-MS) were used to determine the composition (monomer ratios) and structure (end group analysis) relative to 1H NMR spectroscopy and theoretical predictions for three different copolymers: poly(butyl acrylate/vinyl acetate) (PBA/PVAc), poly(methyl methacrylate/vinyl acetate) (PMMA/PVAc) and poly(butyl acrylate/methyl methacrylate) (PBA/PMMA). We found that the ESI results were in excellent agreement with 1H NMR spectroscopy for PBA/PVAc and PBA/PMMA copolymers whereas there was more divergence in the case of PMMA/PVAc. In the case of PBA/PMMA copolymers similar distributions of products were observe by ESI-MS and MALDI-MS with the two major products classes differing by their end-groups. One class has hydrogen and dodecylthio end groups while in the other the dodecylthio has been replaced by alpha-cyanoisopropyl from the initiator. The relative abundance of these distributions as a function of copolymer conversion for a series of reaction conditions was investigated by both ESI and MALDI. MALDI results consistently underestimated (relative to ESI) the butylacrylate monomer ratio in PBA/PMMA and the abundance of co-polymer oligomers terminated by a dodecylthio group from the chain transfer agent.