Anionic Initiators Research Articles

Emulsifier-free emulsion copolymerization of styrene with quaternary ammonium cationic monomers

Emulsifier-free emulsion binary copolymerizations of styrene with four types of quaternary ammonium cationic monomers, diallyldimethylammonium chloride (DADMAC), (3-(methacryloylamino) propyl) trimethyl ammonium chloride (MAPTAC), (2-methacryloyloxy) ethyl) trimethyl ammonium chloride (MATMAC), and vinylbenzyl trimethyl ammonium chloride (VBTMAC), were conducted at 70°C. 2, 2'-azobis (2-methylpropionamidine) dihydrochloride (V50) and potassium persulphate (KPS) were used as cationic and anionic initiator, respectively. Ternary copolymerizations were also carried out in the presence of acrylamide as a second comonomer. Monomer conversions were followed by ultraviolet spectroscopy and the polymer microparticles were characterized using photon correlation spectroscopy, electrophoresis, colloid titration, and scanning electron microscopy. The results indicated that VBTMAC and MATMAC were highly reactive in the copolymerization with styrene whereas the incorporation of DADMAC was slow. MAPTAC had an intermediate reactivity. Binary copolymerization with VBTMAC, MATMAC, and MAPTAC produced particles smaller in size, but higher in surface-charge density, than styrene homopolymer particles. However, significant agglomerates were detected in the VBTMAC and MATMAC-containing latexes. In contrast, DADMAC-containing polymer particles were almost identical to styrene particles. Continuous nucleation took place in the binary copolymerizations with VBTMAC and with MATMAC when using V50 initiator. In the case of using KPS, VBTMAC-containing particles grew continuously to a mean size much larger than the corresponding particles initiated by V50. The presence of acrylamide reduced DADMAC-containing particle size and diminished the agglomeration in the VBTMAC- and MATMAC-containing latexes. The results were interpreted via particle formation mechanism. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 1129–1140, 2000

Unprecedented polymerization ofδ-valerolactone initiated by the stable enolate ofγ-butyrolactone

Polymerization of δ-valerolactone has been studied using γ-butyrolactone enolate as initiator. Mechanistic studies show that the initiation proceeds with incorporation of the initiator into the growing polymer chain and acyl-oxygen bond cleavage of the monomer. The molecular weight distribution of the resulting polymers is narrow compared to that of poly(δ-valerolactone) obtained from common anionic initiators, e. g. alkali metal alkoxides.

Synthesis and Polymerization Behavior of 7-Cyano-7-(phenyl)benzoquinone Methide

A novel captodatively substituted benzoquinone methide, 7-cyano-7-(phenyl)benzoquinone methide (3), was synthesized successfully as an isolable crystal at room temperature. 3 polymerized spontaneously on dissolving it in highly polar, basic solvents such as DMSO and DMF. The acid-catalyzed 1,6-addition reaction of 3 was investigated. Acid-catalyzed 1,6-addition reactions of 3 with phenol and N,N-dimethylaniline afforded 1:1 adducts. In the reaction with hydrogen chloride, a 1,6-addition adduct was also formed. Homopolymerizations of 3 and 7,7-di(cyano)benzoquinone methide (1a) with radical, anionic, and cationic initiators were investigated. 3 and 1a are homopolymerizable with an anionic initiator but not with radical and cationic ones. 3 is copolymerizable spontaneously with styrene in an alternating fashion. The copolymer structure of 3 with styrene was determined on the basis of the spectral data of model compounds and the polymerization mechanism was discussed.

Synthesis and structure of poly(phenyl isocyanate)s bearing an optically active alkoxyl group

Novel optically active phenyl isocyanate derivatives (1–6) bearing an (R)-sec-butoxy, (S)-2-methylbutoxy or (S)-3,7-dimethyloctyloxy group at the meta or para position on the phenyl ring were prepared and polymerized with an anionic initiator in tetrahydrofuran (THF). The resulting polymers from 1, 2, 4 and 6 showed much greater specific rotation than that of the corresponding monomers and an intense circular dichroism (CD) band in the main-chain absorption region, indicating that these polymers have a predominantly one-handed helical conformation in solution. On the other hand, the polymers obtained from 3 and 5 showed a much smaller specific rotation than that of the above polymers at room temperature. The polymers from 2 and 5 showed a remarkable change in optical activity with change in temperature, and the specific rotation of the polymers changed from a positive to a negative value with decrease in temperature. The CD band of the polymers in the absorption region due to the main chain changed from a positive to a negative peak with a change in specific rotation. These results indicate that poly-2 and poly-5 undergo a thermally induced helix–helix transition in THF. The temperature for the helix–helix transition of poly-2 was independent of the degree of polymerization. Poly-2 exhibited a reversible helix–helix transition in chloroform and diethyl ether and also in THF, whereas in toluene and dichloromethane such a transition was not observed. Copyright © 2000 John Wiley & Sons, Ltd.

Haloacetaldehyde polymers and macromolecular asymmetry

Polyhaloaldehydes play a special role in aldehyde polymerization. The most prominent trihaloacetaldehyde polymer, polytrichloroacetaldehyde, opened the door to new concepts in polymer chemistry: first, cryotachensic polymerization, the separation of the initiation step from the propagation steps with the ceiling temperature principle for the fabrication of insoluble and infusible polymers, and second, the concept of macromolecular asymmetry and stereospecific and conformationally specific polymerization. Trichloroacetaldhyde could be readily polymerized with a wide range of anionic (and also some cationic) initiators. When the anionic polymerization was initiated with chiral anions, it gave polychloral of one helix sense. To understand the genesis of the polymerization, the oligomerization was investigated to learn how the stereochemistry of the polymerization was established, also in chiral form. All 10 fluoro-, chloro-, and bromo-substituted trihaloacetaldehydes were synthesized as necessary and polymerized, and the polymers were investigated. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 2623–2634, 2000

Samarium enolate on crosslinked polystyrene beads: anionic initiator for well defined synthesis of polymethacrylate on a solid support

Download options Please wait... Article information DOI https://doi.org/10.1039/B007259L Article type Communication Submitted 07 Sep 2000 Accepted 06 Nov 2000 First published 29 Nov 2000 Download Citation Chem. Commun., 2000, 2503-2504 BibTex EndNote MEDLINE ProCite ReferenceManager RefWorks RIS Permissions Request permissions Samarium enolate on crosslinked polystyrene beads: anionic initiator for well defined synthesis of polymethacrylate on a solid support M. Tanaka, A. Sudo, F. Sanda and T. Endo, Chem. Commun., 2000, 2503 DOI: 10.1039/B007259L To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page. If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given. If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page. Read more about how to correctly acknowledge RSC content. Social activity Tweet Share Search articles by author Masayoshi Tanaka Atsushi Sudo Fumio Sanda Takeshi Endo

Hydrophilic magnetic polymer latexes. 2. Encapsulation of adsorbed iron oxide nanoparticles

The encapsulation of seed polymer particles coated by anionic iron oxide nanoparticles has been investigated using N-isopropylacrylamide as a main monomer, N,N-methylene bisacrylamide as a crosslinking agent, itaconic acid as a functional monomer and potassium persulfate as an anionic initiator. The magnetic latexes obtained have been characterized with regard to particle size, iron oxide content and electrophoretic mobility. All these properties have been examined by varying several polymerization parameters: reaction medium, monomer(s) and crosslinking agent concentrations, nature of seed latexes and type of polymerization (batch versus shot process). The magnetic content in the polymer microspheres strongly depends on the polymerization procedure (i.e., encapsulation process) and varies between 6 and 23 wt%, and monodisperse magnetic polymer particles were obtained.

Preparation and characterization of polymer micelles from poly(ethylene glycol)-poly(d,l-lactide) block copolymers as potential drug carrier

Poly(ethylene glycol)-poly(d,l-lactide) block copolymers (PEG-PLA) with varying composition were prepared through successive ring-opening polymerization of ethylene oxide and d,l-lactide using an anionic initiator, and their property of multimolecular micellization in aqueous milieu was examined in detail from the standpoint of designing carriers for hydrophobic drugs. The heterogeneity of PEG-PLA was found to crucially affect the size and distribution of micelles, and narrowly-distributed micelles with sizes of ∼30 nm in diameter were formed only from PEG-PLA with a substantially narrow molecular weight distribution and an appropriate balance in the length ratio of the PEG and PLA segments in PEG-PLA, indicating the importance of establishing a reliable synthetic route for the block copolymers. PEG-PLA micelles have a considerably low critical association concentration (∼1.0 mg/l) which is apparently an advantage in utilizing these micelles as drug carriers in an extremely diluted condition.

Polyolefins Containing Reactive p-Methylstyrene Groups: From High Tm Thermoplastics to Low Tg Elastomers

This paper summarizes the experimental results in a new class of polyolefin co- and terpolymers containing "reactive" p-methylstyrene (p-MS) groups, which includes the materials from high T m thermoplastics to low T g elastomers. Due to the extraordinary copolymerization capability of metallocene catalysts with constrained ligand geometry, p-MS can be effectively copolymerized with α-olefins (i.e., ethylene, propylene, 1-octene, etc.) to form co- and terpolymers having narrow molecular weight and composition distributions. Comparing with other relative styrenic comonomers, i.e., styrene, o-methylstyrene and m-methylstyrene, p-MS shows significantly higher reactivity in metallocene catalysis. In turn, the incorporated p-MS units in polyolefins are very versatile, which not only can be interconverted to various functional groups, such as -OH, -COOH, anhydride, silane and halides, but also can be conveniently transformed to "stable" anionic initiators for "living" anionic graft-from polymerization reactions. Many new functional polyolefin graft co-polymers have been prepared, containing polyolefin backbone (PE, EP, EO, etc.) and functional polymer side chains, such as PMMA, PAN, PS, etc.

Ring-opening polymerization of strained metallocenophanes: a new route to high molecular weight poly(metallocenes)

Ring-opening polymerization (ROP) of strained ring-tilted metallocenophanes can be achieved thermally, via anionic initiation, or by the use of transition metal catalysts and provides access to a wide range of high molecular weight (Mwa 10 5 -10 6 ,M n> 10 5 ) poly(metallocenes). These materials possess a variety of interesting properties and many are very easy to prepare. This article provides an overview of our work with an emphasis on recent research directions. For example, poly(ferrocene) homopolymers have potential as novel charge dissipation materials. Poly(ferrocene) block copolymers, on the other hand, offer opportunities for the preparation of self-assembled nanoscale micellar aggregates in block selective solvents and applications as anisotropic semiconductors and as nanolithographic patterning materials (e.g. via block selective etching processes) in the solid state.

Polymerization of optically active 2-fluorophenyl-4-fluorophenyl-2-pyridylmethyl methacrylate with anionic and radical initiators: Stereospecificity and helix-sense selection

Almost optically pure (+)- and (−)-2-fluorophenyl-4-fluorophenyl-2-pyridylmethyl methacrylate (2F4F2PyMA) monomers were obtained by HPLC resolution of the racemic monomer and polymerized with the use of anionic and free-radical initiators. Helix-sense selectivity during the polymerization seemed to be governed mainly by the chirality of the monomer itself, and the polymers obtained by using the complex of N,N′-diphenylethylenediamine monolithium amide with (S)-(+)-1-(2-pyrrolidinylmethyl)pyrrolidine (PMP) in toluene at −78°C appeared to possess single-handed helical conformation (+)-poly[(−)-2F4F2PyMA], [α]365 + 1510°; (−)-poly[(+)-2F4F2PyMA], [α]365 − 1610°]. The single-handed helical (+)-poly[(−)-2F4F2PyMA] and (−)-poly[(+)-2F4F2PyMA] obtained with the PMP complex exhibited better chiral recognition ability toward trans-stilbene oxide compared with the single-handed helical poly(rac-2F4F2PyMA) prepared previously. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 2645–2648, 1999

The synthesis of a hydrocarbon-soluble organolithium anionic initiator. A gas–liquid chromatography study of the efficiency of the reaction of s-butyllithium with p-divinylbenzene

The extent of conversion of the reaction between sec-butyllithium and p-divinylbenzene was evaluated by quantitative gas–liquid chromatography. The reaction of stoichiometric amounts of ultra-high purity sec-butyllithium with pure p-divinylbenzene at 0°C produces an anionic initiator, 1,4-bis(1-lithio-3-methylpentyl)benzene, 2, in essentially quantitative yields, with low concentrations of monofunctional impurities. Upon the addition of 10mol% excess of triethylamine to sec-butyllithium, the reaction of sec-butyllithium with p-divinylbenzene at 0°C yielded a homogeneous product with composition of 96% difunctionality and 4% monofunctionality, with the total disappearance of p-divinylbenzene as observed by GLC.The high purity 1,4-bis(1-lithio-3-methylpentyl)benzene initiator, 2, is an effective initiator for 1,3-butadiene polymerizations in hydrocarbon solvents and allows the synthesis of polybutadienes with microstructures ranging from 13% to 16% 1,2-vinyl content, as observed by 1H NMR analysis.

Preparation of Poly(cyanoacetylene) Using Late-Transition-Metal Catalysts

Poly(cyanoacetylene) has been prepared by polymerization of cyanoacetylene using a variety of late-transition-metal (Pd- and Ni-based) catalysts. The effect of reaction conditions on molecular weight and polymer yield was explored. Significant catalyst residues remain in the polymer samples. However, spectra are consistent with the proposed poly(cyanoacetylene) structure. Notable differences in molecular weight, effective conjugation length, and ability to undergo thermal cyclization to a supposed aromatic ladder polymer were observed between these polymers and those prepared using conventional anionic or radical initiators.

Novel synthesis of functionalized poly(3-hydroxybutanoic acid) and its copolymers

Novel feasibility of fuctionalized poly(3-hydroxybutanoic acid), PHB, and its copolymers synthesis via ring-opening of β-butyrolactone (ROP) mediated by activated anionic initiators or enzymes in vitro is presented. Using these new synthetic approaches, PHB with defined chemical structure of the end groups as well as block, graft and random copolymers have been obtained and characterized by IR, NMR, ESI-MS and GPC techniques. The relationship between the structure and properties of the novel polymeric materials prepared is discussed.

A Novel Breakable Cross-Linker and pH-Responsive Star-Shaped and Gel Polymers

A bifunctional methacrylate monomer, namely, ethylene glycol di(1-methacryloyloxy)ethyl ether (1), was prepared through the addition reaction between ethylene glycol divinyl ether and methacrylic acid. 1 was used as a cross-linker in the preparation of a star-shaped poly(methyl methacrylate) [poly(MMA)], a branched soluble poly(MMA), and a polymer gel. The addition of 1 to an anionically prepared living poly(MMA) solution generated a star-shaped polymer with a central poly(1) gel core and several poly(MMA) arms. On the other hand, when MMA and 1 were simultaneously added to a tetrahydrofuran (THF) solution of an anionic initiator, a branched soluble poly(MMA) or a polymer gel was obtained, depending on the amount of 1. The cross-linking points in the above polymers could be easily broken by hydrolysis under acidic conditions, leading to linear polymers. In contrast to the common polymer gels, the present polymer gel could be broken to soluble polymers in an acidic medium. However, it was just swollen in a...

Poly(4-vinyltriphenylamine): synthesis and application as a hole transport layer in light-emitting diodes

An efficient synthesis of 4-vinyltriphenylamine has been developed. This monomer has been polymerised using both anionic and free radical initiators to provide polymers suitable for casting films from solution. Light emitting diodes have been fabricated using this polymer as a hole transport layer (HTL). Comparable devices have been fabricated using evaporated triphenylamine or N,N'-diphenyl-N,N'-ditolylbenzidine as the HTL. Devices with the polymeric HTL display a greater brightness than those with the evaporated layers.

Stereostructures of hydrogenated poly(1,4-(1-arylbutadienes)) prepared by anionic initiators studied by means of NMR

Poly(1,4-(1-phenylbutadiene)) (poly1BP) and poly(1,4-(1-biphenylylbutadiene)) (poly1BPB) polymerized anionically in tetrahydrofuran (THF) have microstructures of 90.9 and 96.4% of 1,4 units, and 9.1 and 3.6% of 3,4 units, respectively, as determined by 400 MHz 1H NMR. However, poly(1,4-(1-naphthylbutadiene)) (poly1NB) and poly(1,4-(1-phenanthrylbutadiene)) (poly1PAB) have 1,4 structures only. The 13C NMR spectra of the alternating copolymers of arylethylenes and ethylene obtained by hydrogenation of the poly(1,4-(1-arylbutadienes)) show a fine structure that can be attributed to dyad or triad stereosequences. These spectra indicate that the alternating (arylethylene/ethylene) copolymers prepared from poly1BPB, poly1NB, and poly1PAB slightly favor isotactic structures.

Stereostructures of hydrogenated poly(1,4-(1-arylbutadienes)) prepared by anionic initiators studied by means of NMR

Stereostructures of hydrogenated poly(1,4-(1-arylbutadienes)) prepared by anionic initiators studied by means of NMR

Synthesis and polymerization ofN-(4-tetrahydropyranyl-oxyphenyl)maleimide

N-(4-Tetrahydropyranyl-oxy-phenyl)maleimide (THPMI) was prepared and polymerized by radical or anionic initiators. THPMI could be polymerized by 2,2′-azobis(isobutyronitrile) (AIBN) and potassium tert-butoxide. Radical polymers (poly(THPMI)r) were obtained in 15–50% yields for AIBN in THF at 65°C after 2–5 h. The yield of anionic polymers (poly(THPMI)a) obtained from potassium tert-butoxide in THF at 0°C after 20 h was 91%. The molecular weights of poly(THPMI)r and poly(THPMI)a were Mn = 2750–3300 (Mw/Mn = 1.2–3.3) and Mn = 11300 (Mw/Mn = 6.0), respectively. The difference in molecular weights of the polymers was due to the differences in the termination mechanism of polymerization and the solubility of these polymers in THF. The thermal decomposition temperatures were 205 and 365°C. The first decomposition step was based on elimination of the tetrahydropyranyl group from the poly(THPMI). Positive image patterns were obtained by chemical amplification of positive photoresist composed of poly(THPMI) and 4-morpholinophenyl diazonium trifluoromethanesulfonate used as an acid generator. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 341–347, 1999

Synthesis and Conformational Characteristics of Poly(phenyl isocyanate)s Bearing an Optically Active Ester Group

Optically active phenyl isocyanates (1−9) bearing an optically active ester group were synthesized and polymerized with an achiral anionic initiator. The resulting polymers from 1 and 4−9 showed a much greater specific rotation than that of the corresponding monomer and an intense circular dichroism (CD) band caused by the main-chain absorption, indicating that these polymers have a predominantly one-handed helical conformation in solution. On the other hand, the polymers obtained from 2 and 3 showed a much smaller specific rotation and a weaker CD band than poly-1, which suggests that, as the distance between the polymer main chain and the asymmetric center on the side chain increases, the asymmetric center cannot effectively induce an excess of one helical twist sense of the polymer main chain at room temperature. However, the specific rotation and CD intensity of poly-2 greatly increased because of a predominantly one-handed helical conformation at low temperatures. The polymers obtained from 3−9 did not show such a temperature effect on conformational change. Specific rotation of the copolymers of chiral 8 and achiral 10 changed from a positive to a negative value with an increase in the content of the optically active unit. The helicity of the copolymer may depend on the composition.