B-polystyrene Triblock Copolymers Research Articles

The aggregation of polystyrene- b-poly(ethylene oxide)- b-polystyrene triblock copolymers in aqueous solution

The aggregation of PS 4- b-PEO 227- b-PS 4 triblock copolymer (the PS and PEO are abbreviations of polystyrene and poly(ethylene oxide), and the subscripts represent the degree of polymerization) in aqueous solution was investigated by Nuclear Magnetic Resonance, Fluorescence Probe, and Transmission Electron Microscope techniques. The experimental results showed that the aggregation did occur and the critical concentration for aggregation was about 0.01 g/l. When the concentration of colloid solution was 10 g/l, the spherical aggregate with a highly polydispersity and radii ranging from 100 to 500 nm was observed. The possible structures of primary micelles and micellar aggregates were proposed. Additionally, the aggregation of PS 43- b-PEO 45- b-PS 43 and PS 18- b-PEO 45- b-PS 18 block copolymers was primarily concerned. The spherical aggregates with a certain size distribution were observed by Transmission Electron Microscope.

Synthesis and characterization of polystyrene-b-poly(ethylene oxide)-b-polystyrene triblock copolymers by atom-transfer radical polymerization

Well-defined polystyrene (PS)-b-poly(ethylene oxide) (PEO)-b-PS triblock copolymers were synthesized by atom-transfer radical polymerization (ATRP), using C—X-end-group PEO as macroinitiators. The triblock copolymers were characterized by infrared spectroscopy, nuclear magnetic resonance spectroscopy, and gel permeation chromatography. The experimental results showed that the polymerization was controlled/living. It was found that when the number-average molecular weight of the macroinititors increased from 2000 to 10,000, the molecular weight distribution of the triblock copolymers decreased roughly from 1.49 to 1.07 and the rate of polymerization became much slower. The possible polymerization mechanism is discussed. According to the Cu content measured with atomic absorption spectrometry, the removal of catalysts, with CHCl3 as the solvent and kaolin as the in situ absorption agent, was effective. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 2882–2888, 2000

Preparation and Spectroscopic Properties of Phenanthrene-Labeled SEBS Triblock Copolymers

Phenanthrene-labeled poly(styrene-b-poly(ethylene-co-butylene)-b-polystyrene triblock copolymers (SEBS) have been prepared from a maleated derivative of the polymer. The dye was attached either through an imine or an ester linkage. The model compound 4, N-phenanthrylmethyl succinimide, exhibits an exponential fluorescence decay in deaerated THF solution, with a lifetime of τ0 = 44.5 ns. However, the fluorescence decays of the labeled SEBS polymers, both in film and in solution, could only be fitted with a sum of three exponential functions, with lifetimes approximately equal to 2, 14, and 44 ns. The long lifetime coincides with that of unquenched phenanthrene. The shortest lifetime, 2 ns, was attributed to polystyrene (PS) emission and could be corrected using the decay of the PS component of unlabeled SEBS (τPS ≈ 2 ns). The 14 ns lifetime appears to be a result of phenanthrene self-quenching brought about by local aggregation, driven not by the dye itself but by the functional group used to attach the dy...

Diblock and triblock functional copolymers by controlled radical polymerization

Controlled polystyrenes with different molar mass values were synthesized starting from benzoyl peroxide and TEMPO (2,2,6,6-tetramethylpiperidinyl-1-oxy). The polystyrene homopolymers served as initiators for the block copolymerization of phthalimide methylstyrene (PIMS) to synthesize polystyrene-b-poly(PIMS) diblock copolymers. Diblock copolymers with well defined structures as well as controlled and narrow molar mass distribution were obtained from the lower-mass polystyrene homopolymers. The lower-mass copolymers were found to be active as initiators in the synthesis of the polystyrene-b-poly(PIMS)-b-polystyrene triblock copolymers. In each reaction step, the effects of conversion and reaction time on the molar mass characteristics of the prepared block copolymers were investigated. The diblock and triblock copolymers were modified using hydrazine as the reagent in order to obtain the corresponding functional amino block copolymers. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 1237–1244, 1999

Diblock and triblock functional copolymers by controlled radical polymerization

Controlled polystyrenes with different molar mass values were synthesized starting from benzoyl peroxide and TEMPO (2,2,6,6-tetramethylpiperidinyl-1-oxy). The polystyrene homopolymers served as initiators for the block copolymerization of phthalimide methylstyrene (PIMS) to synthesize polystyrene-b-poly(PIMS) diblock copolymers. Diblock copolymers with well defined structures as well as controlled and narrow molar mass distribution were obtained from the lower-mass polystyrene homopolymers. The lower-mass copolymers were found to be active as initiators in the synthesis of the polystyrene-b-poly(PIMS)-b-polystyrene triblock copolymers. In each reaction step, the effects of conversion and reaction time on the molar mass characteristics of the prepared block copolymers were investigated. The diblock and triblock copolymers were modified using hydrazine as the reagent in order to obtain the corresponding functional amino block copolymers. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 1237–1244, 1999

Micellization of Polystyrene-b-poly(ethylene/butylene)-b-polystyrene Triblock and Polystyrene-b-poly(ethylene/propylene) Diblock Copolymers in n-Octane

Static and dynamic light scattering and viscometry experiments were performed to study the micellization thermodynamics, micelle structural parameters, and micelle size distribution of a polystyrene-b-poly(ethylene/propylene) diblock copolymer, SEP2, and a polystyrene-b-poly(ethylene/butylene)-b-polystyrene triblock copolymer, SEBS2, in n-octane solutions. n-Octane is a selective solvent for the olefin blocks. Both copolymers have similar chemical composition and molar mass, but whereas SEP2 will form classical micelles, SEBS2 will have to form micelles with a corona constituted by loops of the middle poly(ethylene/butylene) block in order to bring the two end polystyrene blocks into the core and it is also conceivable that some of these end blocks become extended into solution. The influence of the different micelle architecture in the micellization process was analyzed. Standard thermodynamic functions of micellization were determined from light scattering measurements. All the functions obtained for SEBS2 are much smaller than those for SEP2. SEBS2 micelles have also lower association number and size than those for SEP2. Interestingly, an aggregation process of micelles was detected for SEBS2 solutions at relatively low concentration whereas in the SEP2 solutions only micelles with a narrow size distribution were observed. The different behaviors observed for both copolymers confirm the possible structure suggested above for a triblock copolymer dissolved in a selective solvent of the middle block.

Micellization of Polystyrene-b-Poly(ethylene/butylene)-b-Polystyrene Triblock Copolymers in 4-Methyl-2-pentanone

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMicellization of Polystyrene-b-Poly(ethylene/butylene)-b-Polystyrene Triblock Copolymers in 4-Methyl-2-pentanoneManuel Villacampa, Jose R. Quintana, R. Salazar, and Issa KatimeCite this: Macromolecules 1995, 28, 4, 1025–1031Publication Date (Print):February 1, 1995Publication History Published online1 May 2002Published inissue 1 February 1995https://doi.org/10.1021/ma00108a033RIGHTS & PERMISSIONSArticle Views118Altmetric-Citations25LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (886 KB) Get e-Alerts Get e-Alerts