“Charge transfer” polymerization—and the absence thereof!

Mechanisms for “charge‐transfer” spontaneous polymerizations and cycloadditions between electron‐rich olefins and electron‐poor olefins were reviewed. As for propagation, literature proposals involving charge‐transfer complexes were rejected. Instead, alternating copolymerization is ascribed to polar effects in free‐radical reactions. As for spontaneous initiation, literature proposals involving charge‐transfer complexes, with or without proton transfer, were rejected. Instead, the initiating species is postulated to be a tetramethylene zwitterion biradical, which may initiate either ionic homopolymerization or free‐radical copolymerization. A new hypothesis proposes that any interaction that brings vinyl monomers close together may facilitate tetramethylene formation and spontaneous polymerization. These interactions include Coulombic, acid–base, hydrophobic–hydrophilic and templating–tethering interactions. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2069–2077, 2001     

Radical polymerization behavior of a vinyl monomer bearing five‐membered cyclic carbonate structure and reactions of the obtained polymers with amines

Radical polymerization behavior of a vinyl substituted cyclic carbonate, 4‐phenyl‐5‐vinyl‐1,3‐dioxoran‐2‐one ( 1 ), is described. Radical polymerization of 1 proceeded through selective vinyl polymerization to produce polymers bearing carbonate groups in the side chain, in contrast to that of an oxirane analogue of 1 , 1‐phenyl‐2‐vinyl oxirane that proceeds via the selective ring‐opening fashion. Although the homopolymerization of 1 produce polymers in relatively lower yield, copolymerizations effectively provided cyclic carbonate‐containing copolymers. Nucleophilic addition of primary amines to the resulting homopolymers and copolymers produced the corresponding multifunctional polymers. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 584–592, 2005     

Effect of the solvent polarity on the living ligated anionic polymerization of tert-butyl methacrylate and copolymerization with methyl methacrylate

An anionic polymerization of t-butyl methacrylate and a copolymerization with methyl methacrylate were initiated with an organolithium ligated with 10 equiv of LiCl. As a rule, the complexation of the active species by LiCl masked the effect that the polarity of the solvent might have on the molecular structure of the chains. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1774–1785, 2001     

Radical copolymerization of 2‐trifluoromethylacrylic monomers. I. Kinetics of their copolymerization with norbornenes and vinyl ethers as studied by in situ 1H NMR analysis

Radical copolymerizations of electron‐deficient 2‐trifluoromethylacrylic (TFMA) monomers and electron‐rich norbornene derivatives and vinyl ethers with azobisisobutyronitrile were investigated by analyzing the kinetics in situ with ¹H NMR. Although none of the monomers underwent radical homopolymerization under normal conditions, they copolymerized readily, producing a copolymer containing 60–70 mol % TFMA. Terpolymerization involving these monomers was also investigated. The rates of copolymerization and kinetic chain lengths were determined in some cases on the basis of the in situ kinetics analysis. These radial copolymerizations of TFMA provide a basis for the preparation of chemical‐amplification resist polymers for emerging 157‐nm lithography. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1468–1477, 2004     

Single-electron and two-electron transfer in the anionic polymerization of vinyl monomers and the ring-opening polymerization of lactones*

Single-electron-transfer (SET) and two-electron-transfer reactions and their mechanisms were examined in the anionic polymerization of vinyl monomers and in the ring-opening polymerization of lactones. SET resulted in the formation of radical anions or enolates at the initiation step of styrene or lactone polymerization with naphthalene sodium as a catalyst. However, alkali-metal supramolecular complexes such as M⁺crown–M⁻ (M = Na or K) were able to transfer two electrons to both these monomers to form carbanions as reactive intermediates. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2158–2165, 2002     

Synthesis and radical polymerization of 2-vinyldibenzothiophene

A monomer having dibenzothiophene moiety, 2-vinyldibenzothiophene (1), was prepared by the Ni-catalyzed cross-coupling reaction of vinyl bromide with the Grignard reagent of 2-bromodibenzothiophene. The radical homopolymerization of 1 and the copolymerization with styrene were carried out at 60°C in toluene (1.0M) for 20 h using AIBN (5 mol %) as an initiator to obtain the corresponding polymers in high yields. Thermal analyses of the copolymers showed that both 10% weight loss and glass transition temperatures increase when increasing the content of 1 unit. The monomer reactivity ratio was evaluated as r₁ = 2.55 (1) and r₂ = 0.16 (styrene). © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 2813–2819, 1997     

Synthesis of brush‐shaped polymers consisting of a poly(phenylacetylene) backbone and pendant poly(vinyl ether)s via selective reaction of 2‐Vinyloxyethyl 4‐Ethynylbenzoate

We have newly designed an original bifunctional monomer (PAVE) containing both a phenylacetylene (PA) group and a vinyl ether (VE) group, which is expected to be a key material for the synthesis of brush‐shaped polymers consisting of a poly(phenylacetylene) (polyPA) main chain and polyVE side chains. Actually, we have demonstrated the selective chemical transformation of the VE moiety of PAVE to an initiator site for the living cationic polymerization of isobutyl vinyl ether (IBVE), and then succeeded in the controlled synthesis of a novel PA‐end‐capped polyIBVE macromonomer. Moreover, using this macromonomer, the first synthesis of a brush‐shaped polyPA bearing polyVE side chains was achieved via Rh complex‐mediated homopolymerization. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 2800–2805     

Effects of solvent as an electron-pair acceptor on propagation reactions during radical polymerization and copolymerization of polar vinyl monomers

We carried out radical homopolymerization and copolymerization in various kinds of solvents at 60°C by using diisopropyl fumarate (DiPF) and methyl methacrylate (MMA) as electron-accepting polar monomers and styrene (St) and vinyl benzoate (VB) as electron-donating monomers. The highest polymerization rate was observed in the polar and electron-pair accepting solvents, such as 2,2,2-trifluoroethanol for the homopolymerization and copolymerization of these monomers. It has been revealed that the polymerization rate is correlated to the electron-pair–accepting property of the solvent used, rather than the polarity in the linear free energy relationship. We have demonstrated the validity of the acceptor number as the index for interpreting the interaction of the solvent with the monomer and the propagating chain end. The monomer reactivity ratios were determined for the St–DiPF, VB–DiPF, and St–MMA copolymerizations. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 2803–2814, 1999     

Anionic hydrogen‐transfer polymerization of N‐isopropylacrylamide under microwave irradiation

Anionic hydrogen‐transfer homopolymerization of N‐isopropylacrylamide (NIPAAm) was carried out using t‐BuOK as an initiator in DMF under microwave irradiation. After 100 W of microwave was irradiated to the reaction mixture at 140°C for 6 h in the temperature control mode, corresponding polymer was obtained in 10% yield. In the case of conventional oil bath heating, by contrast, corresponding polymer was not obtained in similar anionic polymerization conditions. With 100 W and 2.45 GHz of microwave irradiation, formation of the polymer was obtained. Microwave‐assisted anionic hydrogen‐transfer copolymerization of NIPPAm and acrylamide (AAm) led to the formation of thermo‐sensitive copolymers whose thermo‐sensitivity was controlled by the NIPAAm/AAm unit ratio. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 2415–2419     

Oxazoline‐terminated macromonomers by the alkylation of 2‐methyl‐2‐oxazoline

Well‐defined macromonomers of poly(ethylene oxide) and poly(tert‐butyl methacrylate) were obtained by anionic polymerization induced directly by the carbanion issued from 2‐methyl‐2‐oxazoline. When ethylene oxide was added to this carbanion with lithium as the counterion, a new compound able to initiate the polymerization of ε‐caprolactone in an anionically coordinated way was synthesized, and this led to well‐defined poly(ε‐caprolactone) macromonomers. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2440–2447, 2005     

Bicyclobutanes and cyclobutenes: Unusual carbocyclic monomers

Bicyclobutanes and cyclobutenes substituted with electron‐attracting groups represent novel classes of reactive monomers. They readily undergo free‐radical and anionic polymerizations to give high polymers consisting of 1,3‐ and 1,2‐enchained cyclobutane rings, respectively. They also copolymerize readily with conventional vinyl monomers. These polymers display numerous attractive properties in comparison with their vinyl counterparts, including enhanced thermal stability, superior optical properties, and higher glass‐transition temperatures. The syntheses of these monomers are reviewed, and suggestions toward future larger scale production are made. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 625–635, 2003     

Graft copolymerization of acrylonitrile onto polystyrene

It is possible to graft vinyl monomers, such as acrylonitrile, onto polystyrene via anionic processes but not by a radical process. Both homopolymerization of the added acrylonitrile and graft copolymerization in which acrylonitrile units are added to the para position on the benzene ring in styrene occur; the conversion of acrylonitrile into polymer depends upon the time and temperature of the reaction and on the concentration of the anionic initiator, butyllithium. A constant 15–20% of the acrylonitrile is converted to graft copolymer while the remainder is homopolymerized; graft copolymer may be separated from homopolymer by selective precipitation from either N,N′-dimethylformamide or aqueous potassium thiocyanate. Treatment of the mixed graft and homopolymer with aqueous sodium hydroxide converts the nitrile into an acid salt and one may conveniently separate homopolymer from graft copolymer in this way. Each polystyrene chain is grafted with acrylonitrile units. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 1275–1282, 1997     

Application of ketenes to well-defined polyester synthesis. III. Living anionic polymerization of ethyl(4-methoxyphenyl)ketene—Development of polyester having masked phenol side chain

A novel ketene, ethyl(4-methoxyphenyl)ketene (EMPK), was synthesized by the dehydrochlorination of 2-(4-methoxyphenyl)butanoyl chloride. The anionic polymerizations of EMPK by butyllithium in tetrahydrofuran at −20 °C were carried out with a varying feed ratio to give the corresponding polyesters having predictable molecular weights and narrow molecular weight distributions, quantitatively. The selective formation of the polyester was confirmed by IR analysis, and the reductive degradation of the polymer was supported by lithium–aluminium hydride. The second feed of the monomer (after the first stage of polymerization) resulted in the formation of the polymer with the expectedly increased molecular weight and low polydispersity to strongly support the living mechanism of this polymerization. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1596–1600, 2001     

New polymers derived from 4‐vinylsilylbenzocyclobutene monomer with good thermal stability,excellent film‐forming property,and low‐dielectric constant

A series of benzocyclobutene (BCB) polymers derived from a new readily available monomer, 4‐(1′,1′‐dimethyl‐1′‐vinyl) silylbenzocyclobutene (4‐DMVSBCB), were conveniently prepared by radical and anionic polymerization. The homo‐ and co‐polymerization results show that the reactivity of 4‐DMVSBCB in anionic polymerization is relatively higher compared with radical polymerization. The molecular weight of 4‐DMVSBCB polymers and content of 4‐DMVSBCB can be controlled by anionic copolymerization. The introduction of rigid and crosslinkable BCB building blocks in side chains and carbosilanes in molecule gives rise to insulating materials with good film‐forming property, smooth and flat film surface, and low‐dielectric constants of 2.41–2.45, as preserving good thermal stability. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

A novel route to poly(2-hydroxyethyl methacrylate) and its amphiphilic block copolymers

The vinyl of the ester group of 2-vinyloxyethyl methacrylate was first selectively reacted with acetic acid to obtain 2-[1-(acetoxy)ethoxy]ethyl methacrylate ( 2 ). This protected monomer was subjected to anionic polymerization in tetrahydrofuran at −60°C in the presence of LiCl, using 1,1-diphenylhexyllithium as initiator. The molecular weight of the polymer could thus be controlled and a narrow molecular weight distribution obtained. The protecting group, 1-(acetoxy)ethyl, could be easily eliminated (by quenching the polymerization reaction with methanol and water) to generate poly(2-hydroxyethyl methacrylate) (poly(HEMA)). Block copolymers were also prepared by the sequential anionic polymerization of MMA and 2 or styrene and 2 . They possess narrow molecular weight distributions, and controlled molecular weights and compositions. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1865–1872, 1998     

Copolymerization of vinyl acetate with 1-octene and ethylene by cobalt-mediated radical polymerization

The cobalt-mediated radical polymerization of vinyl acetate was extended to copolymerization with 1-alkenes (ethylene or 1-octene). In agreement with the low amount of 1-alkene that could be incorporated into the copolymer, a gradient structure was predictable, but a rather low polydispersity was observed. A poly(vinyl acetate)-b-poly(octene) copolymer was also successfully synthesized, leading to a poly (vinyl alcohol)-b-poly(octene) amphiphilic copolymer upon the methanolysis of the poly (vinyl acetate) block. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2532–2542, 2007     

Expanding vinyl ether monomer repertoire for ring-expansion cationic polymerization: Various cyclic polymers with tailored pendant groups

Herein, we clarified the ring-expansion cationic polymerization with a cyclic hemiacetal ester (HAE)-based initiator was versatile in terms of applicable vinyl ether monomers. Although there was a risk that higher reactive vinyl ethers may incur β-H elimination of the HAE-based cyclic dormant species to irreversibly give linear chains, the polymerizations were controlled to give corresponding cyclic polymers from various alkyl vinyl ethers of different reactivities. Functional vinyl ether monomers were also available, and for instance a vinyl ether monomer carrying an initiator moiety for metal-catalyzed living radical polymerization in the pendant allowed construction of ring-linear graft copolymers through the grafting-from approach. Furthermore, ring-based gel was prepared via the addition of divinyl ether at the end of the ring-expansion polymerization, where multi HAE bonds cyclic polymers or fused rings were crosslinked with each other. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 3082–3089     

Preparation of functionalized block copolymers based on a polysiloxane backbone by anionic ring‐opening polymerization

Polysiloxane diblock copolymers containing a pure polysiloxane backbone were prepared by the functionalization of poly(dimethylsiloxane)‐b‐poly(methylvinylsiloxane) copolymers. The copolymers were obtained by the sequential anionic copolymerization of either 1,3,5,7‐tetramethyl‐1,3,5,7‐tetravinylcyclotetrasiloxane or 1,3,5‐trimethyl‐1,3,5‐trivinylcyclotrisiloxane with hexamethylcyclotrisiloxane. The two vinyl monomers showed large differences in the propagation rates, but both could be used for the formation of polysiloxane block copolymers. Differences in the polymerization sequences were investigated and revealed that better control was obtained if the slower propagating monomer was polymerized first. The method permitted the synthesis of block copolymers with molecular weight distributions around 1.4 and lower and high block purities. The vinyl groups of the block copolymers were quantitatively and selectively functionalized by hydrosilation or epoxidation reactions. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1539–1551, 2002     

Designing of dipeptide‐based oligoconjugates as potential carrier for drug delivery. Pyroglutamil‐S‐glutamic acid bisoligo‐3‐hydroxybutyrates

In the present article, we describe the synthesis and characterization of conjugates based on pyroglutamyl‐S‐glutamic acid and bisoligo‐[R,S]‐3‐hydroxybutyrates (PyGlu‐S_‐Glu_bisOHB) using anionic ring opening polymerization of β‐butyrolactone with a dipeptide bearing two carboxylate groups as potassium salt. The results indicated that the above‐mentioned reaction is accompanied of oligomerization of β‐butyrolactone yielding (3‐hydroxybutyrates) oligomers with crotonate and carboxyl end groups. We report also the end group analysis of the synthesized conjugates using electrospray ionization tandem mass spectrometry (ESI‐MS), the latter confirmed the presence of a mixture of dipeptide conjugate with β‐butyrolactone oligomer chain and β‐butyrolactone homopolymer. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4103–4111, 2008     

Stabilization and kinetics in the emulsion copolymerization of butyl acrylate and methyl methacrylate

We carried out emulsion homopolymerizations and copolymerizations of butyl acrylate (BuA) and methyl methacrylate (MMA) with different types and concentrations of surfactants to determine the influence of these parameters on the particle size and particle size distribution and to elucidate the mechanism of particle formation. As expected, the mechanisms of nucleation above and below the critical micelle concentration were very different; however, it was also found that the presence of partially soluble monomers such as MMA in the water phase had a significant influence on the critical micelle concentration of Triton X‐405 (>50%). In addition, the nucleation mechanism during copolymerization seemed to be dominated by BuA, with the number of particles per liter being very similar to the number nucleated during its homopolymerization. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2832–2846, 2001