Synthesis of polymers containing conjugated dienyl end-groups by means of anionic living polymerization

In order to synthesize end-functionalized polymers with conjugated dienyl groups, living polymeric anions of polystyrene and polyisoprene were allowed to react with 5-bromo-1,3-pentadiene, 1, and 7-bromo-1,3-heptadiene, 2. The reaction of polystyryl anion and/or polyisoprenyl anion with 1 gave polymers whose end-functionalities were 65–80% regardless of the reaction conditions. On the other hand, almost quantitative functionalization was achieved when a large excess amount of 2 was used as a terminator. When 1,1-diphenylalkyl anion and enolate anion derived from t-butyl methacrylate were used, the degree of end-functionality were 70–80% at best. The resulting end-functionalized polymers were characterized by size exclusion chromatography (SEC), ¹H and ¹³C-NMR and thin layer chromatography coupled with a flame ionization detector (TLC-FID). © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 3464–3472, 1999     

Functional polymers by living anionic polymerization

The application of living anionic polymerization techniques for the functionalization of polymers and block copolymers is reviewed. The attachment of functional groups to polymeric chains of predetermined lengths and narrow molecular weight distributions is described. Carboxyls, hydroxyls, amines, halogens, double bonds, and many other functional groups can be placed at one or two ends in the center or evenly spaced along polymeric chains. Subsequent transformations of the functional groups further contribute to the versatility of such treatments. General methods based on the use, as terminators, of substituted haloalkanes, as well as the addition of living polymers or their initiators to diphenylethylenes, substituted with appropriate functional groups or molecules, are discussed. Another approach, based on the living polymerization of monomers with protected functional groups, is also discussed. It has been used for the preparation of polymers and copolymers with evenly spaced functional groups. The combination of living anionic polymerization techniques with controlled radical and cationic polymerizations is also described. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2116–2133, 2002     

Synthesis of well‐defined functionalized polymers and star branched polymers by means of living anionic polymerization using specially designed 1,1‐diphenylethylene derivatives

This article covers precise syntheses of well‐defined chain‐end and in‐chain functionalized polymers, multi‐functionalized polymers with a definite number of functional groups, star‐branched and graft polymers by recently developed methodologies using specially designed 1,1‐diphenylethylene (DPE) derivatives. The DPE derivatives include various substituted DPE derivatives with functional groups and their derivatives, DPE‐functionalized DPE derivatives, and well‐defined DPE‐functionalized macromonomers. The synthetic utility and importance of these DPE derivatives are described via such polymer syntheses.     

Synthesis of heteroarm star polymers comprising poly(4-methylphenyl vinyl sulfoxide) segment by living anionic polymerization

<正>A series of 3-arm ABC and AA'B and 4-arm ABCD,AA'BC and AA′A″B heteroarm star polymers comprising one poly(4-methylphenyl vinyl sulfoxide) segment and other segments such as polystyrene,poly(α-methylstyrene), poly(4-methoxystyrene) and poly(4-trimethylsilylstyrene) were synthesized by living anionic polymerization based on diphenylethylene(DPE) chemistry.The DPE-functionalized polymers were synthesized by iterative methodology,and the objective star polymers were prepared by two distinct methodologies based on anionic polymerization using DPE-functionalized polymers.The first methodology involves an addition reaction of living anionic polymer with excess DPE-functionalized polymer and a subsequent living anionic polymerization of 4-methylphenyl vinyl sulfoxide(MePVSO) initiated from the in situ formed polymer anion with two or three polymer segments.The second methodology comprises an addition reaction of DPE-functionalized polymer with excess sec-BuLi and a following anionic polymerization of MePVSO initiated from the in situ formed polymer anion and 3-methyl-1,1-diphenylpentyl anion as well.Both approaches could afford the target heteroarm star polymers with predetermined molecular weight,narrow molecular weight distribution (M_w/M_n1.03) and desired composition,evidenced by SEC,~1H-NMR and SLS analyses.These polymers can be used as model polymers to investigate structure-property relationships in heteroarm star polymers.     

Synthesis of well‐defined polymers end‐functionalized with crosslinkable aziridine groups by living anionic polymerization

Well‐defined end‐functionalized polystyrene, poly(α‐methylstyrene), and polyisoprene with polymerizable aziridine groups were synthesized by the termination reactions of the anionic living polymers of styrene, α‐methylstyrene, and isoprene with 1‐[2‐(4‐chlorobutoxy)ethyl]aziridine in tetrahydrofuran at ?78 °C. The resulting polymers possessed the predicted molecular weights and narrow molecular weight distributions (weight‐average molecular weight/number‐average molecular weight < 1.1) as well as aziridine terminal moieties. The cationic ring‐opening polymerization of the ω‐monofunctionalized polystyrene having an aziridinyl group with Et₃OBF₄ gave the polymacromonomer, whereas the α,ω‐difunctional polystyrene underwent crosslinking reactions to afford an insoluble gel. Crosslinking products were similarly obtained by the reaction of the α,ω‐diaziridinyl polystyrene with poly(acrylic acid)‐co‐poly(butyl acrylate). © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4126–4135, 2005     

Precise synthesis of thermo-responsive and water-soluble star-branched polymers and star block copolymers by living anionic polymerization

A series of thermo-responsive and water-soluble 4- and 8-arm star-branched poly(2-(2′-methoxyethoxy)ethyl methacrylate) (poly(1)) with well-defined structures were synthesized by living anionic polymerization of 1, followed by a linking reaction with a core compound substituted with either four or eight benzyl bromide moieties. Furthermore, two kinds of sequentially different 4-arm star block copolymers composed of poly(1)-block-poly ((2,2-dimethyl-1,3-dioxolan-4-yl)methyl methacrylate) (poly(4)) were also synthesized by the same linking reaction of the corresponding AB or BA diblock copolymer anion with a core compound substituted with four benzyl bromide moieties. Thus, both well-defined 4-arm (AB)₄ and (BA)₄ star-block copolymers, whose A and B are poly(1) and poly(4) segments, were successfully synthesized. These star-block copolymers were quantitatively converted to the corresponding 4-arm (AC)₄ and (CA)₄ star-block copolymers with the same compositions by hydrolytic acetal cleavage of the poly(4) segment to poly(2,3-dihydroxypropyl methacrylate) (C segment). Poly(1) segments have LCST values and, on the other hand, both water-insoluble poly(4)s and water-soluble poly(2,3-dihydroxypropyl methacrylate)s are non-thermo-responsive segments. The thermo-responsive behavior of the resulting 4- and 8-arm star-branched poly(1) as well as the 4-arm (AB)₄, (BA)₄, (AC)₄, and (CA)₄ star-branched block copolymers has been extensively studied in terms of molecular weight, arm number, composition, and block sequence. As expected, such variables were observed to affect their LCST values. Interestingly, the thermo-responsive behavior of the 4-arm (AC)₄ and (CA)₄ stars was different from that of the block copolymers used as arm segments.     

Synthesis of asymmetric star-branched polymers consisting of three or four different segments in composition by means of living anionic polymerization with a new dual-functionalized 1,1-bis(3-chloromethylphenyl)ethylene

A series of four-armed A₂BC, AB₂C, and ABC₂ asymmetric star-branched polymers with a three-component system, the A, B, and C segments of which are polystyrene, polyisoprene, and poly(4-trimethylsilylstyrene), respectively, have been successfully synthesized with a methodology based on living anionic polymerization with dual-functionalized 1,1-bis(3-chloromethylphenyl)ethylene ( 1 ). These star-branched polymers have well-defined architectures and precisely controlled chain lengths, as confirmed by size exclusion chromatography, ¹H and ¹³C NMR, vapor pressure osmometry, and static light scattering analyses. A simple and convenient one-pot process for star-branched polymer synthesis is an additional advantage of this methodology. One problem to be solved is that the synthetic route is limited in some cases by the inherently low reactivity of polyisoprenyllithium toward the 1,1-diphenylethylene functionality of in-chain-functionalized polymers. A new four-armed ABCD star-branched polymer, the A, B, C, and D segments of which are polyisoprene, poly(4-methoxystyrene), polystyrene, and poly(4-trimethylsilylstyrene), could also be synthesized through the extension of the methodology using 1 to a four-component system. The successful results strongly demonstrate the synthetic versatility and potential of this methodology for a wide variety of well-defined asymmetric star-branched polymers. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4535–4547, 2004     

Synthesis of graft polymers with poly(isoprene) as main chain by living anionic polymerization mechanism

The graft polymers [poly(isoprene)‐graft‐poly(styrene)] (PI‐g‐PS), [poly(isoprene)‐graft‐poly(isoprene)] (PI‐g‐PI), [poly(isoprene)‐graft‐(poly(isoprene)‐block‐poly(styrene))] PI‐g‐(PI‐b‐PS), and [poly(isoprene)‐graft‐(poly(styrene)‐block‐poly(isoprene))] PI‐g‐(PS‐b‐PI) with PI as main chain were synthesized through living anionic polymerization (LAP) mechanism and the efficient coupling reaction. First, the PI was synthesized by LAP mechanism and epoxidized in H₂O₂/HCOOH system for epoxidized PI (EPI). Then, the graft polymers with controlled molecular weight of main chain and side chains, and grafting ratios were obtained by coupling reaction between PI^?Li⁺, PS^?Li⁺, PS‐b‐PI^?Li⁺, or PI‐b‐PS^?Li⁺ macroanions and the epoxide on EPI. The target polymers and all intermediates were well characterized by SEC,¹H NMR, as well as their thermal properties were also evaluated by DSC. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Preparation of functional polymers by living anionic polymerization: Polymerization of allyl methacrylate

The anionic polymerization of allyl methacrylate was carried out in tetrahydrofuran, both in the presence and in the absence of LiCl, with a variety of initiators, at various temperatures. It was found that (1,1-diphenylhexyl)lithium and the living oligomers of methyl methacrylate and tert-butyl methacrylate are suitable initiators for the anionic polymerization of this monomer. The temperature should be below −30°C, even in the presence of LiCl, for the living polymerization to occur. When the polymerization proceeded at −60°C, in the presence of LiCl, with (1,1-diphenylhexyl)-lithium as initiator, the number-average molecular weight of the polymer was directly proportional to the monomer conversion and monodisperse poly(allyl methacrylate)s with high molecular weights were obtained. ¹H-NMR and FT-IR indicated that the α CC double bond of the monomer was selectively polymerized and that the allyl group remained unreacted. The prepared poly(allyl methacrylate) is a functional polymer since it contains a reactive CC double bond on each repeating unit. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 2901–2906, 1997     

Synthesis of water-soluble fullerene-containing vinyl polymers by low-temperature radiation-induced living polymerization

Water-soluble polymers of acrylamide and acrylic acid that contain fullerene (more than 90% C₆₀) have been prepared by the low-temperature radiation-induced living polymerization. In the absorption spectra of these polymers, a monotonically decaying absorption typical of the covalently bound fullerene or its associates is observed in the range 240–700 nm. The radiation initiation of the process allows preparation of high-purity polymers useful for designing medicinal preparations.     

Metal-complex-bearing star polymers by metal-catalyzed living radical polymerization: Synthesis and characterization of poly(methyl methacrylate) star polymers with Ru(II)-embedded microgel cores

One-pot, spontaneous, and in-situ incorporation of Ru(II) complexes into a microgel (solubilized nanometer-scale network) has been achieved in near quantitative efficiency by a polymer-linking reaction of linear living poly(methyl methacrylate) (PMMA) with a bifunctional methacrylate (ethylene glycol dimethacrylate or bisphenol A dimethacrylate; linking agent) and a phosphine-ligand monomer [diphenyl-4-styryl-phosphine ( 3 ); i.e., CH₂CH C₆H₄ p-PPh₂] in the RuCl₂(PPh₃)₃-catalyzed living radical polymerization. The products were Ru-bearing. PMMA-armed star polymers with a microgel-core that consisted of a copolymer network of the linking agent and 3 . Upon the network formation, the phosphine ligands efficiently encapsulated RuCl₂(PPh₃)₃, thus achieving a polymer catalyst directly from a polymerization catalyst. Colored dark brown-red, the star polymers exhibited UV-vis absorptions originating from the entrapped complex (3.1–7.4 × 10⁻⁵ mol Ru/g of polymer), the incorporation efficiency being close to 100% with respect to the original polymerization-catalyst. Detailed spectroscopic characterization showed the following: an absolute molecular weight of 1.7 × 10⁵ to 1.7 × 10⁶, an arm number of 11–92 arms/polymer, and a radius of gyration of 8–19 nm (in DMF). Direct observation of the individual star molecules in solid state was achieved by transmission electron microscopy (unstained; 2–3 nm dark dots for the core) and atomic force microscopy (semi-circular images). © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4966–4980, 2006     

Synthesis of low polydispersity polybutadiene and polyethylene stars by convergent living anionic polymerization

Star‐shaped polybutadiene stars were synthesized by a convergent coupling of polybutadienyllithium with 4‐(chlorodimethylsilyl)styrene (CDMSS). CDMSS was added slowly and continuously to the living anionic chains until a stoichiometric equivalent was reached. Gel permeation chromatography‐multi‐angle laser light scattering (GPC‐MALLS) was used to determine the molecular weights and molecular weight distribution of the polybutadiene polymers. The number of arms incorporated into the star depended on the molecular weight of the initial chains and the rate of addition of the CDMSS. Low molecular weight polybutadiene arms (M_n = 640 g/mol) resulted in polybutadiene star polymers with an average of 12.6 arms, while higher molecular weight polybutadiene arms (M_n = 16,000 g/mol) resulted in polybutadiene star polymers with an average of 5.3 arms. The polybutadiene star polymers exhibited high 1,4‐polybutadiene microstructure (88.3–93.1%), and narrow molecular weight distributions (M_w/M_n = 1.11–1.20). Polybutadiene stars were subsequently hydrogenated by two methods, heterogeneous catalysis (catalytic hydrogenation using Pd/CaCO₃) or reaction with p‐toluenesulfonhydrazide (TSH), to transform the polybutadiene stars into polyethylene stars. The hydrogenation of the polybutadiene stars was found to be close to quantitative by ¹H NMR and FTIR spectroscopy. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 828–836, 2006     

Structure of polymers formed by anionic polymerization of adipimide

Products obtained by anionic polymerization of adipimide contain foreign structures derived from 6-oxo-1,11-undecanedioic acid, as a result of base catalysed condensation. The decrease in adipimide units, however, is much greater than corresponds to the number of oxodicarboxylic acid units so that there must be additional reactions consuming adipimide units. At short polymerization periods, the polymers are mostly crosslinked; the fraction of insoluble polymer decreases with increasing temperature and time of polymerization. Even at low polymerization temperatures, the content of adipimide monomer units in the polymers is below 90 per cent. Therefore, the polymerization products have to be considered as copolymers rather than as homopolymers.     

Controlled synthesis of functionalized polymers by transition‐metal‐mediated living radical polymerization

This paper discusses recent progress in transition‐metal‐catalyzed living radical polymerizations, partly focusing on the search of metal complex catalysts that play a critical role in controlling polymer molecular weights, then‐distributions, and architectures. Following a brief overview of the design of initiating systems (initiators and metal catalysts), half‐metallocene‐type complex catalysts are presented that induce living radical polymerizations of methacrylates, acrylates, and styrene to give markedly narrow molecular weight distributions and controlled molecular weights. Some of these halfmetallocenes also work in water where suspension living radical polymerization is feasible.     

Synthesis of novel hydrocarbon polymers containing 6‐membered rings in the main chain: living anionic polymerization of 1,3‐cyclohexadiene

The n‐butyllithium (n‐BuLi)/N,N,N',N'‐tetrametylethylene‐diamine (TMEDA) system (the molar ratio of TMEDA to n‐BuLi higher than 4/4) has been found to polymerize 1,3‐cyclohexadiene (1,3‐CHD) to produce “living” polymer having narrow molecular weight distribution with well‐controlled polymer chain length. Binary and ternary block copolymers with narrow molecular weight distribution could be synthesized from 1,3‐cyclohexadiene, styrene, and butadiene with very high efficiency. These polymers and their hydrogenated derivatives have excellent thermal, mechanical, chemical, and optical properties for the new industrial materials.     

Synthesis of ultra-high-molecular-weight polyacrylonitrile by anionic polymerization

The anionic polymerization of acrylonitrile in DMF initiated by lithium 1,2-bis(diethylamino)-2-oxoethanolate in the range ?60 to 0°C has been studied. The initiator efficiency at low temperatures (?60 to ?40°C) is 2–6%; it remains nearly invariable with conversion owing to the associated state of the initiator. The low concentration of growing active centers is constant throughout the process; as a result, polymers with M > 3 × 10⁵ are produced. The polymers are characterized by a narrow molecular-mass distribution, M _w/M _n = 1.3–1.6, and contain insignificant amounts of low-molecular-mass fractions. It has been shown that controlled polymerization processes can be carried outat moderately low temperatures (?30 to 0°C), and experimental conditions for freezing of polymerization and its recommencement have been ascertained. Optimum conditions for the synthesis of a high-molecular-mass polyacrylonitrile with M > 3 × 10⁵ have been established, and the method for preparing polymers with M = (6.50–8.5) × 10⁵ on an enlarged scale using high concentrations of the monomer has been developed.     

Synthesis and characterization of amphiphilic triblock polymers by copper mediated living radical polymerization

2-Dimethylaminoethyl methacrylate (DMAEMA) and 2-diethylaminoethyl methacrylate (DEAEMA) block copolymers have been synthesized by using poly(ethylene glycol), poly(tetrahydrofuran) (PTHF) and poly(ethylene butylenes) macroinitiators with copper mediated living radical polymerization. The use of difunctional macroinitiator gave ABA block copolymers with narrow polydispersities (PDI) and controlled number average molecular weights (M_n’s). By using DMAEMA, polymerizations proceed with excellent first order kinetics indicative of well-controlled living polymerization. Online ¹H NMR monitoring has been used to investigate the polymerization of DEAEMA. The first order kinetic plots for the polymerization of DEAMA showed two different rate regimes ascribed to an induction period which is not observed for DMAEMA. ABA triblock copolymers with DMAEMA as the A blocks and PTHF or PBD as B blocks leads to amphiphilic block copolymers with M_n’s between 22 and 24 K (PDI 1.24-1.32) which form aggregates/micelles in solution. The critical aggregation concentrations, as determined by pyrene fluorimetry, are 0.07 and 0.03 g dm⁻¹ for PTHF- and PBD-containing triblocks respectively.     

Synthesis of carbosilane block copolymers by means of a living anionic polymerization of 1,1-diethylsilacyclobutane

Block polymerization of 1,1-diethylsilacyclobutane with styrene derivatives and methacrylate derivatives was investigated. Sequential addition of styrene to a living poly(1,1-diethylsilabutane), which was prepared from phenyllithium and 1,1-diethylsilacyclobutane in THF–hexane at −48°C, gave poly(1,1-diethylsilabutane)-b-polystyrene. Similarly, addition of 4-(tert-butyldimethylsiloxy)styrene to the living poly(1,1-diethylsilabutane) provided poly(1,1-diethylsilabutane)-b-poly(4-(tert-butyldimethylsiloxy)styrene). Poly(1,1-diethylsilabutane)-b-poly(methyl methacrylate) was obtained by treatment of living poly(1,1-diethylsilabutane) with 1,1-diphenylethylene followed by an addition of methyl methacrylate. Poly(1,1-diethylsilabutane)-b-poly(2-(tert-butyldimethylsiloxy)ethyl methacrylate) was also synthesized by adding 2-(tert-butyldimethylsiloxy)ethyl methacrylate to the living poly(1,1-diethylsilabutane) which was end-capped with 1,1-diphenylethylene in the presence of lithium chloride. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 2699–2706, 1998