Methacryloyl End Group Research Articles

Synthesis and polymerization of first‐generation dendritic methacrylate macromonomers

AbstractFirst‐generation dendritic macromonomers with a methacryloyl end group on one side, long alkyl chains on the other side, and a biuret system with two urethane groups in the core have been synthesized. The synthesis comprises three steps with hexamethylene diisocyanate uretdione as the starting material. The branching points were introduced via biuret groups and the prepared macromonomers were polymerized by free and controlled radical polymerization. Depending on the reaction conditions linear dendronized polymers as well as branched dendronized polymers and microgels with long alkyl chains were obtained. Scanning force microscopy was used to visualize high molecular weight molecules spincoated on highly oriented pyrolytic graphite. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 614–628, 2007

Polymacromonomers with polyolefin branches synthesized by free‐radical homopolymerization of polyolefin macromonomer with a methacryloyl end group

AbstractPolymacromonomers with polyolefin branches were successfully synthesized by free‐radical homopolymerization of polyolefin macromonomer with a methacryloyl end group. Propylene‐ethylene random copolymer (PER) with a vinylidene end group was prepared by polymerization using a metallocene catalyst. Then, the unsaturated end group was converted to a hydroxy end group via hydroalumination and oxidation. The PER with the hydroxy end group was easily reacted with methacryloyl chloride to produce methacryloyl‐terminated PER (PER macromonomer; PERM). The free‐radical polymerization of thus‐obtained PERM was done using 2,2′‐azobis(isobutyronitorile) (AIBN) as a free‐radical initiator. From NMR analyses, the obtained polymers were identified as poly(PERM). Based on gel permeation chromatography (GPC), the estimated degree of polymerization (Dp) of these polymers were about 30. Thus, new class of polymacromonomers with polyolefin branches was synthesized.

Synthesis and degradation of poly (2-hydroxyethyl methacrylate)- graft-poly (ε-caprolactone) copolymers

Poly (ε-caprolactone) macromonomers carrying a methacryloyl end groups were synthesized using different lanthanide derivatives as catalysts, and characterized by SEC and 1H NMR. Hydrophilic–hydrophobic copolymers from macromonomers and 2-hydroxyethyl methacrylate (HEMA) were obtained by solution free radical polymerization. Depending on the feed ratio of the two components, different copolymer structures were obtained. The expected graft structure of the copolymers was confirmed by 1H NMR. Thermal properties of the copolymers were determined by DSC and TGA. Hydrolytic and enzymatic degradations of the materials were performed. Poly (2-hydroxyethyl methacrylate)- graft-poly (ε-caprolactone) copolymers containing 33 or 50% of PCL showed only a weak hydrolysis of the powders and no enzymatic degradation. After 49 days, only PCL with a HEMA motive to its chain-end was entirely degraded by the Lipase PS from Pseudomonas cepacia.

SYNTHESIS OF MACROMONOMER USING END FUNCTIONAL POLYSTYRENE PREPARED FROM p-METHOXYBENZYL p-TRIMETHYL-SILYLPHENYL SELENIDE AS A PHOTOINIFERTER

The end functional polystyrene having phenylseleno group at ω-chain end was prepared from radical polymerization of styrene in the presence of p-methoxybenzyl p-trimethylsilylphenyl selenide as a photoiniferter. The phenylseleno group at ω-chain end in polystyrene was eliminated by hydrogen peroxide. The resulting polystyrene was interconverted quantitatively to polystyrene having epoxy end group by the oxidation with m-chloroperbenzoic acid. The macromonomer having a meth-acryloyl end group was synthesized from polystyrene containing epoxy end group with methacrylic acid in xylene at 140°C. Copolymerization of this macromonomer with methyl methacrylate afforded effectively a graft copolymer composed of a poly-(methyl methacrylate) backbone and polystyrene branches.

Controlled Radical Copolymerization of Styrene and the Macromonomer of PEO with a Methacryloyl End Group

The amphiphilic copolymer with uniform poly(ethylene oxide) as side chains was prepared by initiating of AIBN polymerization of methacryloyl-terminated PEO macromonomer (PEOM) and styrene (St) in the presence of 4-hydroxyl-2,2,6,6-tetramethylpiperidine-1-oxy (HTEMPO). The copolymerization is controllable, the molecular weight of the copolymer and the conversion of the monomer increase with the polymerization time, and the distribution is rather narrow and is in the range 1.23−1.33. It was confirmed that the relative reactivity of PEOM macromonomer decreases with an increase in its molecular weight, and the variation of concentration of HTEMPO and AIBN can affect the copolymerization greatly.

Preparation of a uniform poly(methyl methacrylate) macromonomer and its polymerization

AbstractSyndiotactic poly(methyl methacrylate) (st‐PMMA) macromonomer having methacryloyl end group was prepared from st‐PMMA living anion and separated into uniform macromonomers by means of supercritical fluid chromatography. A uniform macromonomer with the degree of polymerization of 32 was polymerized radically in benzene at 60°C. The uniform dimer, trimer and tetramer of the uniform macromonomer were isolated from the polymerization product by means of gel‐permeation chromatography (GPC). The intrinsic viscosity ([η]) in tetrahydrofuran of these uniform comblike polymers was determined by GPC/differential viscometric analysis. The plot of logarithmic [η] against logarithmic molecular weight indicated that the trimer and tetramer assume a little shrinking molecular shape as compared with the unimer and dimer.

Radical Polymerization Behavior of Polystyrene Macromonomers in the Presence of Inert Polystyrene

Radical polymerizations of polystyrene macromonomers having a methacryloyl end group with Mns of 2900 and 9600 were investigated in the presence of inert polystyrene (PSt) of the same molecular weight. Under homogeneous conditions, the viscosity of polymerization media was fixed with variation in macromonomer concentration ([M]) by fixing the sum of the concentrations of the macromonomer and inert PSt. The presence of the inert PSt increased both the degree of polymerization (DP) of poly(macromonomer)s and polymerization rate (Rp). The observed kinetic order of Rp with respect to [M] decreased by the addition of inert PSt, but remained larger than unity. Termination rate constant (kt) decreased by the addition of inert PSt and increase of [M], while the propagation rate constant (kp) was not affected by inert PSt. kp did not show clear [M]-dependence, irrespective of the presence of inert PSt. These results are discussed in terms of the viscosity of polymerization media, initiator efficiency and specific multibranched structure about the propagating radical.

Radical polymerization behaviour of macromonomers: 3. Effect of macromonomer concentration

The radical polymerization of a polystyrene macromonomer having a methacryloyl end group (with an Mn of 2700), was investigated at various macromonomer concentrations ([M]), in order to study in detail the effect of [M] on the polymerization behaviour. The polymerization rate (Rp), the degree of polymerization (DP), the concentration of the propagating radical ([M∗]), and the initiator efficiency (f) were evaluated by gel permeation chromatography, using an instrument equipped with a laser light scattering detector (l.s.-g.p.c.), and also by electron spin resonance (e.s.r.) spectroscopy. The viscosity of the polymerization solution (η) was also measured, by using an Ubbelohde viscometer. The DP of the formed poly(macromonomer)s changes drastically with [M]. The order of Rp and Rpø12η, with respect to [M], was 2.2 and 1.3, respectively, where øη is the ratio of η of the polymerization system to that of the solvent. This indicates that η alone is not responsible for an order of Rp that is larger than unity. Values for the propagation rate constant (kp) were approximately constant with respect to [M], while those of the termination rate constant (kt) rapidly decreased with increases in [M]. These results are discussed in terms of [M], η, and the segment density around the propagating radical site.

Miscibility of regular multibranched polystyrene with linear polystyrene

Differential scanning calorimetry (d.s.c.) measurements on the 50/50 blends of well-defined multibranched polystyrenes and linear polystyrenes were carried out to investigate the miscibility between polymer components having the same constitutional repeating units but different molecular architectures. Multibranched polystyrenes with different branch number and length were prepared by the radical polymerization of polystyrene macromonomers of different molecular weights possessing a different polymerizable end group, i.e. a vinylbenzyl end group and methacryloyl end group. D.s.c. curves showed one or two thermal transitions corresponding to the glass transitions depending on both the branching architecture of the multibranched polystyrene, namely poly(macromonomer)s, and the molecular weight of the linear polystyrenes. The miscibility between the poly(macromonomer) and the linear polystyrenes decreased with increase in both branch number of poly(macromonomer)s and the molecular weight of the linear polystyrene. The miscibility increases with increase in the branch length but was not much influenced by the chemical structure of the central backbone of the poly(macromonomer)s. These results indicate that the miscibility in the athermal binary multibranched-linear polystyrene blends is influenced by the branching architecture, and the blends locate near the miscible/immiscible boundary.

Study on the Solvent Effect on Radical Polymerization of Polystyrene Macromonomer

Radical polymerizations of polystyrene macromonomers having a methacryloyl end group, Mn of which are 2900 and 12400, were carried out in benzene and methylcyclohexane to study the solvent effect on the polymerization behavior. Radical polymerizations were done at 60°C with AIBN as an initiator under homogeneous condition. Degree of polymerization (DP), polymerization rate (Rp) and concentration of propagating radical ([M*]) were evaluated by a gel permeation chromatogtaphy (GPC) equipped with a laser light scattering detector and an electron spin resonance (ESR) spectroscopy. Intrinsic viscosity ([η]) of macromonomers and formed poly(macromonomer)s in benzene and methylcyclohexane were also measured at the polymerization temperature. It was found that both DP and Rp in methylcyclohexane were larger than those in benzene irrespective of the molecular weight of the macromonomer. From DP, Rp, and [M*], propagation rate constant (kp) and termination rate constant (kt) were evaluated. kt in methylcyclohexane was smaller than that in benzene, while kp in methylcyclohexane was nearly equal to, or slightly larger than, that in benzene. These results were considered in terms of the change in the segment density around the propagating radical site by the solvent nature.

Pyrolysis-gas chromatography for end group analysis of polystyrene macromonomers using stepwise pyrolysis combined with on-line methylation

The end group functionalities of polystyrene macromonomers with methacryloyl (ML) end groups were determined by stepwise pyrolysis-gas chromatography (PyGC) at different temperatures, using a two stage pyrolyser consisting of two independent furnaces, combined with an on-line methylation technique. The macromonomer sample in THF solution was mixed with tetramethylammonium hydroxide in methanol solution, as the methylation reagent, in a sample cup; this was introduced into the first furnace (250°C) of the pyrolyser attached to a gas chromatograph to decompose selectively the ML end group moieties in the macromonomer to methyl methacrylate (MMA). After GC analysis of the formed MMA, the sample cup was dropped down into the second furnace (650°C) to pyrolyse the residual polystyrene main chain thoroughly. The concentration of the ML end groups was determined by comparing the peak intensity of MMA observed in the former pyrogram with those of the characteristic products formed from the polystyrene main chain in the latter pyrogram. The end group functionalities of several macromonomer samples calculated from the concentrations of the end groups, determined by PyGC, were in fairly good agreement with those determined by 1H NMR, and with those calculated from the data of the maximum conversion of the macromonomers.

Radical polymerization behavior of macromonomers. 2. Comparison of styrene macromonomers having a methacryloyl end group and a vinylbenzyl end group

L'etude par diffusion laser et GPC montre que le degre de polymerisation Dp des poly(macromeres) varie fortement avec la concentration du macromere [M] dans la solution. La variation de Dp avec [M] depend fortement de la masse moleculaire du macromere. Les courbes de conversion en fonction du temps sont montones et ne presentent pas d'effet d'autoacceleration. Les constantes de vitesse de propagation et de termination et la duree de vie des radicaux des macromeres sont evaluees

Macromonomer synthesis. New functionalization methods

AbstractSo far, the syntheses of macromonomers by end‐capping of “living” anionic polymers with unsaturated electrophiles, were not always quantitative. Now, we found that macromonomers with unsaturated end groups can be smoothly prepared with quantitative yields from ω‐hydroxy‐poly(ethyleneoxide)s (PEO) applying methods of peptide synthesis. The intermediate PEO with carboxylic, p‐toluenesulfonate or chlorocarbonyl end groups were prepared with quantitative yields. They were transformed into the 4‐vinylphenyl substituted PEO macromonomers by reaction with 2‐(4‐vinylphenyl)ethanol or 4‐vinyl‐aniline, in quantitative yields, in the presence of dicyclohexylcarbodiimide and 1‐hydroxybenzotriazole or triethylamine, respectively. PEO with methacryloyl end groups were prepared from ω‐hydroxy‐PEO and 2‐isocyanato ethyl methacrylate. The resulting macromonomers were characterized by determination of the double bond content and by 1H NMR spectroscopy.