Search results for "Addition polymer"

Mechanism of anionic polymerization of methyl methacrylate in the presence of aluminium alkyls

1995

Methyl methacrylate was polymerized with tert-butyl lithium in the presence of triethylaluminium or triisobutylaluminium at 78°C in toluene. As indicated by GPC and MALDI-TOF mass spectrometry, the polymerization is accompanied by side reactions. The lower oligomers were fractionated by distillation and characterised by NMR, FT-IR, UV and electron impact (EI) mass spectrometry. All these data show that part of the polymer chains are carrying exactly one tert-butyl isoprenyl ketone unit. In order to avoid the formation of tert-butyl isoprenyl ketone a molar ratio of Al/Li>2 is necessary.

Polyether Core-Shell Cylinder-Polymerization of Polyglycidol Macromonomers

2005

The synthesis and polymerization of macromonomers containing a polymerizable styrene head group and a tail of ethylene oxide derivatives of different character were investigated. The synthesis of macromonomers was based on living anionic polymerization of oxiranes. Two monomers were used: 1-ethoxyethyl glycidyl ether (glycidol acetal), which after hydrolysis forms hydrophilic glycidol blocks and glycidyl phenyl ether forming hydrophobic blocks. Polymerizable double bonds were introduced by terminating the living chain with p-(chloromethyl)styrene. The radical polymerization of the macromonomers was carried out in water with addition of a non-polar solvent (benzene) and AIBN as initiator. Co…

A contribution to the kinetics of the polymerization of styrene with CF3SO3H as catalyst

1978

The time dependence of the cationic polymerization of styrene in CH2Cl2 with CF3SO3H as catalyst can be formally described as being first-order with respect to monomer concentration [M]0. The reaction rate shows a third-order dependence in catalyst concentration [C]0. A high polymer and a low polymer polystyrene fraction are found at [M]0>0.2 mole · l−. The reaction rate of the high polymer fraction is proportional to [C] 0 3 , that of the low polymer fraction probably proportional to [C] 0 2 . The polymerization active species may thus be triple ions in the first and ion pairs in the second case.

The kinetics of anionic polymerization of styrene in 1,2-dimethoxiethane

2007

Kinetic measurements in a flow apparatus in combination with conductance measurements, permit the determination of the two equilibrium constants Kes and Kdiss* and the three propagation rate constants k(±)c, k(±)s and k(−) as a function of temperature. The great differences in the polymerization rate in various solvents are mainly caused by their influence on the equilibrium constants. The influence of the solvent on the rate constants is not greater than in other chemical reactions.

Mechanism of Anionic Polymerization of (Meth)acrylates in the Presence of Aluminum Alkyls, 6. Polymerization of Primary and Tertiary Acrylates

1998

The kinetics of the polymerization of n-butyl acrylate initiated by lithiated ester enolates in the presence of aluminum alkyls was investigated in toluene and in toluene/Lewis base mixed solvents at −78 °C. In pure toluene, curved time−conversion plots, incomplete monomer conversion, and broad molecular weight distributions (Mw/Mn ≈ 2) are observedin the absence of aluminum alkyls the molecular weight distributions are significantly broader (Mw/Mn > 14). High monomer conversions and narrower molecular weight distributions (Mw/Mn ≈ 1.5) are obtained when using Lewis bases (e.g., methyl pivalate) as cosolvents. The polymerization of tert-butyl acrylate rapidly reaches full monomer conversion…

PEG-based Multifunctional Polyethers with Highly Reactive Vinyl-Ether Side Chains for Click-Type Functionalization

2011

Introduction of highly reactive vinyl ether moieties along a poly(ethylene-glycol) (PEG) backbone has been realized by copolymerization of the novel epoxide monomer ethoxy vinyl glycidyl ether (EVGE) with ethylene oxide (EO). A series of copolymers with varying structure (block and random) as well as EVGE comonomer content (5-100%) with molecular weights in the range of 3,900-13,200 g/mol and narrow molecular weight distributions (M-w/M-n = 1.06-1.20) has been synthesized and characterized with respect to their microstructure and thermal properties. The facile transformation of the vinyl ether side chains in click type reactions was verified by two different post polymerization modification…

Tapered copolymers of styrene and 4‐vinylbenzocyclobutene via carbanionic polymerization for crosslinkable polymer films

2019

1971

The anionic polymerization of β-propiolactone at 25°C in ethanol initiated by the betain was investigated. Macrozwitterions of the structure were produced, n being intentionally as low as ca. 11. The structure of the product was proven by the nitrogen content of the reprecipiated polymer, by IR and NMR spectroscopy and by titration of the carboxylate endgroups. Some carboxylic acid endgroups were formed by chain transfer with the solvent ethanol. The positive charge at the polymer chain was proven by electrophoresis of polymer after esterification of the carboxylate chain end. Furthermore the dielectric constant of dilute solutions of the polymer in CHCl3 was determined and is discussed. Th…

Dispersion Polymerization of Vinylidene Fluoride in Supercritical Carbon Dioxide

2006

The dispersion polymerization of vinylidene fluoride in supercritical carbon dioxide is investigated using two ammonium carboxylate perfluoropolyether stabilizers of different molecular weights. Under suitable operating conditions a polymer made of well-dispersed spherical particles has been obtained up to relatively high conversion. The experimental data of polymerization rate and molecular weight distribution are in good agreement with the predictions of a model previously developed. Such an agreement supports the conclusion that the polymerization kinetics is dominated by the interphase transport of the active radicals between the continuous phase and the polymer particles.

1993

The influence of lithium tert-butoxide (tBuOLi) and of lithium chloride on the oligomerization of tert-butyl acrylate (tBuA) initiated by tert-butyl α-lithioisobutyrate (tBiB-Li) was investigated. These additives affect both the kinetics and the product distribution. Whereas the addition of LiCl leads to a narrower molecular-weight distribution (MWD) the presence of tBuOLi induces broader MWD's, characterized by a very high fraction of the dimer. Both additives decrease the rates of propagation to different degrees. These effects are discussed on the basis of the formation of aggregates and adducts, the lithiated dimer having a higher tendency to form aggregates than the other oligomers. Th…