Synthesis of low molecular weight polystyrene by anionic techniques and intrinsic viscosity–molecular weight relations over a broad range in molecular weight

Altares, Timothy; Wyman, Donald P.; Allen, V. R.

doi:10.1002/pol.1964.100021021

Cited by 86 publications

(15 citation statements)

References 15 publications

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“…The fractions used were fractions 4 and 9 in the PS-1100 series, and they were chosen for two reasons: (a) they represent the two extremes in this series in terms of backbone molecular weight and branch density (fraction 4, 19,600 and 0.064; fraction 9, 12,800 and 0.171) while having the same total molecular weights, and (b) the polystyrene graft chains of molecular weight 1,100 g./mole behave, in good solvents, as though they were in a theta solvent, and therefore changing the solvents will have no effect on their hydrodynamic properties. This has been conclusively shown by Rossi et al (29) and Altares et al (30) in the case of polystyrene to a molecular weight of approximately 3,000 g./mole and in the case of poly-a-methylstyrene (31) to about 6,000 g./mole.…”

Section: 28supporting

confidence: 62%

Reaction of living polystyrene with some natural polymers and their analogs

O’Malley

Marchessault

1968

J. polym. sci., C Polym. symp.

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SynopsisThe preparation and characterization of graft polymers of methylated xylan and polystyrene are described. The copolymers were prepared anionically by reaction of polystyrylpotassium with the methyl glucuronate moiety, to give well-defined comblike structures. Polystyrenes of molecular weight 1,100 and 4,700 were used. The reaction takes place by attack of the polymeric anion at the ester function, which converts it into a ketone. Infrared analysis has confirmed this, since only a ketone absorption band i s observed in the grafted products. Evaluation of intrinsic viscosity measurements on well-defined copolymer fractions was made in terms of branch density, branch length, and backbone molecular weight. These parameters generally affected the viscosity in the manner predicted for homopolymer branched structures. Reactions of the polystyryl anion with a polyester and a polypeptide were also considered. In general, unwanted side reactions were predominant in these systems. However, in the case of one polyester, polypropiolactone, indications are that block copolymers with polystyrene were prepared, but isolation and characterization of the products was not attempted, because of the low molecular weights involved.

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Section: 28supporting

confidence: 62%

Reaction of living polystyrene with some natural polymers and their analogs

O’Malley

Marchessault

1968

J. polym. sci., C Polym. symp.

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“…The analogous behaviors of MHS plot in the low molecular weight region have been reported for many polymer-solvent systems. [35][36][37][38][39][40] The existent distribution of molecular weights in the polymer samples has to be taken into account in quantitative discussions of dilute solution properties. We are here ultimately interested in a fair estimate of the unperturbed chain dimensions of PET by use of the expression, (29) where l/J 0 and < r 2 > 0 are the viscosity constant and the mean square end to end distance in an ideal state, respectively.…”

Section: On the Sedimentation Datamentioning

confidence: 99%

Ultracentrifugal Characterization of Poly(ethylene terephthalate) in Dilute Solutions

Ohoya

Hasegawa

Tsubakiyama

et al. 2001

Polym J

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ABSTRACT:The well-fractionated poly(ethylene terephthalate) (PET) samples ranging in weight average molecular weight Mw from 0.9 to 16 X 10 4 have been studied by sedimentation velocity and equilibrium, and viscometry in hexafluoroisopropanol (HFIP) and m-cresol at 30°C. The second virial coefficient A2 determined in HFIP by the sedimentation equilibrium method is found to have high dependence on Mw expected for the helical wormlike chains in very good solvents. The constant l/J 113 P-1 in the Mandelkern-Flory equation is 2.54X10 6 for PET in HFIP and 2.57X10 6 in mcresol, being in excellent agreement with that reported for several polymer-solvent systems. In spite of an important polymer that has been widely used for a variety of industrial purposes, poly(ethylene terephthalate) (PET) is not still completely disclosed about its molecular characteristics and solution properties. I-s For example, there is significant disagreement among the constants of K' and a of the Mark-HouwinkSakurada (MHS) relationship, eq 1, compiled for several PET-solvent systems in "Polymer Handbook"; 9where [7]] is the intrinsic viscosity and M is the molecular weight. The reasons for this are that PET is soluble only in a limitted number of rather peculiar and dangerous solvents, such as trifluoroacetic acid (TFA) and achlorophenol (o-CP), and that the establishments of most MHS equations are based on the number average molecular weight Mn using the unfractionated samples. The reliable unperturbed chain dimensions, therefore, have not been determined in terms of the MHS relation proposed.The molecular weight and its distribution for several commercial PET samples have recently been measured in hexafluoroisopropanol (HFIP) by Naoki et al. 10 with light scattering and gel permeation chromatography (GPC). On the other hand, a series of preliminary experiments11·12 revealed that HFIP is an easy handling and very good solvent for PET. In this work, we direct our efforts toward the establishment of rigorous MHS relations for PET in HFIP and m-cresol. For this purpose, the polymer was first fractionated by a column elution method 13 and then the fractions obtained were characterized by sedimentation experiments and viscometry. The results for m-cresol solutions were compared with tTo whom all correspondence should be addressed. those obtained in m-cresol by Meyerhoff and Shimotsuma.2 Sedimentation equilibrium offers the weight average molecular weight Mw and requires least correction for polydispersity. HFIP is available with high refractive index increment dn/dc allowing a measurement at low polymer concentraion and providing good precision in Mw. The viscosity-molecular weight relations thus determined are available for the reliable evaluation of unperturbed chain dimensions ( < r 2 >ofM ) 112 from which the chain conformational parameter CJ is derived by the Stockmayer-Fixman method. 14 According to rather old-fashioned theory of the polymer solutions, 15 the dependences of a part of the molecular parameters obtained on molecular weight ar...

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“…It was noted that with small concentrations of the ether ([THF] = [BuLi]), the initiation reaction becomes very rapid, i.e., too fast to be measured by-the optical methods usually used [30,61] in studies of this system. These characteristics are of value from a synthesis standpoint since it is possible now to prepare samples of monodisperse, low molecular weight (~1000) polystyrene [14,62]. The propagation reaction changes its rate in a rather complex fashion with variations in the THF concentration at a constan t concentration of butyllithium.…”

Section: Polymerization Proceduresmentioning

confidence: 99%

“…At this temperature, at l~ast several days are necessary for complete conver- SIOn. The measurement of viscosity is a convenient mode of determining the molecular weight of polymers prepared by these homogeneous anionic polymerization techniques. Values for K and a for several polymer-solvent pairs have been published; polystyrene [13,14], poly-a-methylstyrene [17], polyisoprene [20,] and polybutadiene [23,24].…”

Section: Polymerization Proceduresmentioning

confidence: 99%

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Procedures for homogeneous anionic polymerization

Fetters¹

1966

J. RES. NATL. BUR. STAN. SECT. A.

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This report is a rev ie w of the procedures and equipm e nt used in the preparation of polyniers of predi ctabl e molec ular weights and narrow mol ec ular weight di stributions. The monomers con sidered in detai l are styre ne, a-methyl styre ne, iso pre ne , and butadiene.Key Words: Ho moge neo us anioni c polymerization, monodi s pe rse, polystyrene, poly-a-me thylstyre ne, polyiso pre ne, an d polybutadiene.

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Synthesis of low molecular weight polystyrene by anionic techniques and intrinsic viscosity–molecular weight relations over a broad range in molecular weight

Cited by 86 publications

References 15 publications

Reaction of living polystyrene with some natural polymers and their analogs

Reaction of living polystyrene with some natural polymers and their analogs

Ultracentrifugal Characterization of Poly(ethylene terephthalate) in Dilute Solutions

Procedures for homogeneous anionic polymerization

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