Anionic Copolymerization Of Styrene Research Articles

Regulation from gradient to near periodic sequence during anionic copolymerization of styrene and dimethyl-[4-(1-phenyl-vinyl)phenyl]silane (DPE-SiH)

A facile strategy for achieving sequence-controlled polymers with a sufficient molecular diversity is of great importance. The periodic and gradient copolymers of styrene (St) and dimethyl-[4-(1-phenylvinyl)phenyl]silane (DPE-SiH) obtained through the living anionic copolymerization (LACOP) under the variable feed ratios (St:DPE-SiH = 0.5–4) in a nonpolar solvent without additives were well studied in our prior work (Zhang et al., 2019) [34]. Herein, a further study on the critical feed ratio of St (S) and DPE-SiH (D) at 3:1 is performed during the LACOP, where a peculiar interest lies whether a novel sequence will emerge between the periodic and gradient sequence with the additives of t-BuOK and THF. As the whole chain propagation process is monitored using in situ1H NMR spectroscopy, the copolymerization kinetics, i.e., the reactivity ratio (r), apparent rate parameters (Kapp.), and the copolymer microstructures are investigated. Both t-BuOK and THF favors the incorporation of St into LACOP, as the trends rSt = 0.1 (gradient sequence without additives) < rSt = 0.22–0.29 (near periodic sequence for t-BuOK) < rSt = 0.7–0.76 (near periodic sequence for THF). The near periodic sequences exhibit different periodicities distributed as “DSSDSS” for the t-BuOK and “DSSSDSSS” for the THF in the major. The strategy achieves the sequence regulation from statistically gradient to near periodic copolymers. Furthermore, we observe that the near periodic copolymers exhibit the similar Tg values but over the gradient copolymers.

Tuning Compositional Drift in the Anionic Copolymerization of Styrene and Isoprene

The properties of polymer materials are largely a result of the local and long-range order of polymer chains and systems of polymer chains. The ability to tune polymer chain architecture at the mon...

Study on the Mechanism of a Side Coupling Reaction during the Living Anionic Copolymerization of Styrene and 1-(Ethoxydimethylsilyphenyl)-1-phenylethylene (DPE-SiOEt).

A 1,1-diphenylethylene (DPE) derivative with an alkoxysilyl group (DPE-SiOEt) was synthesized. It was end-capped with poly(styryl)lithium (PSLi) and then copolymerized with styrene via living anionic polymerization (LAP) in a non-polar solvent at room temperature. The observed side coupling reaction was carefully investigated by end-capping the polymer. Changes in molecular weight support the plausibility of a mechanism involving living anionic species (PSLi or lithiated DPE-end-capped polystyrene, PSDLi) and the alkoxysilyl groups. Through a series of copolymerizations with different feed ratios, the kinetics of the side coupling reaction were also studied. The results showed that the side reactions could be controlled using an excess feed of DPE-SiOEt, a potentially useful strategy for the synthesis and application of well-defined alkoxysilyl-functionalized polymers via LAP.

Electronically excited reactive complexes in the anionic copolymerization of nonpolar monomers

The anionic copolymerization of styrene with nonpolar monomers (butadiene and isoprene) is studied theoretically and experimentally. The known problem of activity transformation, when the monomer more active in homopolymerization becomes less active in copolymerization, is considered. This problem has not previously been solved by traditional theory methods. The structure of complexes of living polymers with monomer molecules and the reaction activation energy are ab initio calculated. The activity of the monomer is shown to be determined by the energy of the electronically excited state of the reactive complex between the monomer molecules and the growing active center.

Further Studies on the Anionic Copolymerization of Styrene and Glycidyl Methacrylate in Toluene

Sequential anionic copolymerization of styrene and glycidyl methacrylate (GMA) was performed with the protection of argon under normal pressure, where styrene, GMA, toluene, THF, n-butyllithium and a small amount of lithium chloride (LiCl) were used as first monomer, second monomer, solvent, polar reagent, initiator and additive, respectively. Polystyrene-b-poly(glycidyl methacrylate) diblock copolymers (PS-b-PGMA) with well-defined structure and narrow molecular weight distribution were prepared by the copolymerization reaction of poly(styryl)lithium with GMA under certain temperatures. The copolymers were characterized using gel permeation chromatography (GPC), 1H-NMR, 13C-NMR, thin layer chromatography (TLC) and hydrochloric acid-dioxane argentimetric methods. The effects of additives, copolymerization temperature and THF dosage on the copolymerization were studied. No chain transfer reaction of anionic polymerization of styrene in toluene was observed. Slightly broader molecular weight distribution of PS-b-PGMA was observed with the increase the GMA repeat units. Using THF/toluene blend solvent could reduce the polydispersity index (M w /M n ) and dissolve the copolymer better than toluene alone. Lower temperature (< -40°C) and LiCl are required to prepare PS-b-PGMA with narrower molecular weight distribution.

Synthesis of Arborescent Copolymers by a One‐Pot Method

AbstractA “grafting from” scheme was developed for the preparation of arborescent copolymers in one single reactor, by anionic copolymerization of styrene with 1,3‐diisopropenylbenzene and activation of the pendent isopropenyl moieties with sec‐butyllithium. Arborescent polystyrene‐graft‐poly(tert‐butyl methacrylate) copolymers were thus obtained by addition of tert‐butyl methacrylate to linear and G0 macroinitiators, respectively. Arborescent polystyrene‐graft‐[polystyrene‐block‐poly(2‐vinylpyridine)] copolymers were also synthesized by successive additions of styrene and 2‐vinylpyridine to the same macroinitiators. The copolymers were characterized by SEC‐MALLS and 1H NMR analysis.magnified image

Effects of 1,2‐butadiene on the anionic copolymerization of styrene and 1,3‐butadiene in the presence of polar additives

Abstract1,2‐Butadiene is shown to be a chain terminating/transferring agent in butyllithium‐initiated diene polymerization. The influence of 1,2‐butadiene on the anionic copolymerization of 1,3‐butadiene and styrene is investigated using n‐butyllithium as initiator and tetrahydrofuran or N,N,N′,N′‐tetramethylethylenediamine as polar additive. A decrease of copolymerization rate is observed on the addition of 1,2‐butadiene. On introducing 1,2‐butadiene, the number average molecular weight (Mn) decreases and the molecular weight distribution broadens. The vinyl content of copolymer increases slightly with an increase of 1,2‐butadiene. During the copolymerization, 1,2‐butadiene in the presence of a high ratio of polar additives to n‐butyllithium greatly decreases the copolymerization rate, resulting in a lower value of Mn and a narrower molecular weight distribution than that found for a low ratio of polar additives to n‐butyllithium. This evolution can be explained by the base‐catalyzed isomerization of 1,2‐butadiene to form 1‐butylene in the presence of polar additives. With an increasing amount of 1,2‐butadiene, the vulcanized rubber exhibits an increased rolling resistance and a reduced wet skid resistance owing to the decrease of coupling efficiency. These results further indicate the activity of alkynyllithium derivatives produced by the reaction of alkyllithium and 1‐butyne is less than that of the alkyllithium. Copyright © 2007 Society of Chemical Industry

Synthesis of networked polystyrene endowed with nucleophilic reaction sites by the living anionic polymerization technique

The living anionic copolymerization of styrene with 1,2-bis(4′-ethenylphenyl)ethane (1) or p-divinylbenzene (PDVB) with sec-butyllithium in benzene was carried out. The copolymerizations of styrene with more than 20 mol % of 1 gave insoluble polymers in quantitative yields, whereas the yield showed the maximum (97%) for PDVB at 15 mol %. The content of unreacted double bonds of the network polymer formed by the copolymerization with PDVB was four times as large as that formed with 1. Gas chromatographic analyses of the copolymerization suggested close reactivities of the double bonds between styrene and 1, whereas a rapid consumption of PDVB compared with styrene was observed in their copolymerization. The r1, r2,and r1r2 values for the copolymerization of styrene with 1 were determined to be 1.00, 1.09, and 1.09, respectively, which suggests that a more homogeneous network structure can be attained with 1. The living chain end of the produced living gel initiated the polymerization of tert-butyl methacrylate to give an insoluble block copolymer in a good yield. The hydrolysis of the ester group of the block copolymer led to an amphiphilic copolymer that exhibited a characteristic property of a hydrogel. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 2543–2547, 2000

Kinetics of arm-first star polymers formation in a non-polar solvent

Star polymer formation by sequential anionic copolymerization of styrene and divinylbenzene in a non-polar solvent (benzene) was re-examined. Kinetic investigations established that the core formation is rather slow. Moreover, once the star molecules have reached their plateau molar mass, their cores still contain residual pendant unsaturations. This result arose from UV spectroscopic determinations, and was checked by sec-butyllithium addition to the star polymer solution. Fractionation experiments confirmed the rather narrow molar mass distribution in star polymer samples obtained by this arm-first process.

The anionic copolymerization behavior of the styrene: p-tert-butylstyrene and styrene:p-methylstyrene monomer pairs in benzene

The anionic copolymerization of styrene:p-tert-butylstyrene and styrene:p-methylstyrene has been studied. In benzene, near statistical copolymers can be formed at 20°C when the lithium counter-ion is used. The addition of tetrahydrofuran (THF) is known to disrupt chain end association. The addition of THF(THF/Active center = 10) to the sytrene:p-tert-butylstyrene system led to virtually no change in the reactivity ratios.

Proprietes physico-chimiques de reseaux polymeriques modeles—I. Caracterisation des parametres de structure

Polystyrene gels were prepared by anionic copolymerization of styrene and divinylbenzene in dilute solution (7.5%), the molecular weight between crosslinks ranging from 6500 to 75,000. We have characterized the molecular parameters of the statistical theory: the number of elastic chains, the functionality of the crosslinks, the memory term and the Flory-Huggins interaction parameter. The results reveal a small influence of the crosslinks on these parameters without the memory term, and no influence of the swelling solvent.

Proprietes physico-chimiques de reseaux polymeriques modeles—II. Influence de la temperature

Polystyrene gels were prepared by anionic copolymerization of styrene and divinylbenzene in dilute solution. There has been a study of the stress-birefringence, as a function of temperature, of these networks swollen to equilibrium in cyclohexane and methylcyclohexane.

Glass transition temperature of ideal polymeric networks

Measurements of the glass transition temperature ( T g ) have been carried out on polystyrene networks prepared by the anionic copolymerization of styrene and divinylbenzene, and star-shaped polystyrene of varying functionality. The results show a linear variation of T g versus M ̄ −1 n in all cases. The value of the slope interpreted in terms of the free volume theory shows that the glass transition temperature depends closely on the average functionality of the crosslinks. In order to study the influence of free chains on the glass transition of crosslinked polymers a series of networks were contaminated with increasing ratios of linear polystyrene chains, slightly polydisperse.

Elastic behaviour of ideal polystyrene networks

Polystyrene gels were prepared by anionic copolymerization of styrene and divinylbenzene in dilute solution (7.5%), the molecular weight between crosslinks ranging from 10 000 to 75 000. A study of the photoelasticity of these networks swollen to equilibrium in benzene and cyclohexane allowed some molecular parameters such as the memory term, the number of elastic chains, the functionality of the crosslinks, and the optical anisotropy of the random links to be calculated. The Mooney—Rivlin representation shows that both in elongation and compression, the C 2 term is nul, the C 1 term becoming identified with the theoretical modulus from the Flory, Wall and Hermans theory.

Anionic Copolymerization of Styrene with p-Divinylbenzene

Anionic Copolymerization of Styrene with p-Divinylbenzene

Anionic copolymerization of styrene and isoprene in cyclohexane

AbstractThe copolymerization of isoprene with styrene initiated with sec‐butyllithium in cyclohexane solution has been studied by kinetic methods. The rates of the homopolymerization have been measured by normal methods. The rates of the cross‐propagation reactions were measured by the rate of appearance or disappearance of the ultraviolet absorption of polystyryllithium when the individual chain ends were reacted with the opposite monomer in the absence of the first. The rates of some of the reactions were also measured in the presence of the other monomer. It was found that polyisoprenyllithium reacted with both monomers with a one quarter‐order dependence, and the polystyryllithium with a one half‐order dependence. It was found possible to describe the copolymerization in terms of the four individual rate constants and to predict the initial copolymer composition. It was not found necessary to resort to explanations based on preferential absorption of isoprene around the chain ends to explain the high isoprene content of the copolymer.

Reconsideration of the kinetics of anionic copolymerization of styrene and methyl methacrylate

Reconsideration of the kinetics of anionic copolymerization of styrene and methyl methacrylate