Precipitation fractionation of block copolymers

1985 ◽  
Vol 50 (11) ◽  
pp. 2588-2597 ◽  
Author(s):  
Zdeněk Tuzar ◽  
Antonín Sikora ◽  
Dagmar Straková ◽  
Jiří Podešva ◽  
Jaroslav Stejskal ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Block Copolymer ◽  
Block Copolymers ◽  
Molar Mass ◽  
Chemical Heterogeneity ◽  
Preparative Separation ◽  
The Real

Possibilities offered by classical precipitation fractionation in the preparative separation of polymer admixtures from block copolymers and in an estimate of the polydispersity in molar mass and of the heterogeneity in chemical composition of block copolymers have been examined. A mixture of a two-block copolymer, polystyrene-block-polyisoprene, with polystyrene was separated in the systems cyclohexane/1-propanol and 1,4-dioxan/1-propanol, and a mixture of three two-block styrene-isoprene copolymers having different chemical composition was fractionated in the system benzene/methanol. In the cyclohexane/1-propanol system, two commercial samples of three-block copolymers polystyrene-block-poly(ethene-co-butene)-block-polystyrene and their mixture were fractionated. The results showed that the polydispersity and chemical heterogeneity thus estimated are much lower than the real ones, especially due to the colloid properties of block copolymers.

Synthesis of multisegmented block copolymer by Friedel–Crafts hydroxyalkylation polymerization

2020 ◽  
Vol 11 (14) ◽  
pp. 2542-2549
Author(s):  
Timothy Cuneo ◽  
Xiaosong Cao ◽  
Lei Zou ◽  
Haifeng Gao
Keyword(s):  
Block Copolymer ◽  
Block Copolymers ◽  
Molar Mass ◽  
High Molar Mass

Friedel–Crafts (FC) polycondensation of 1,4-dimethoxybenzene with 4-substituted benzaldehyde species was used to prepare telechelic oligomers and high-molar-mass multisegmented block copolymers.

scholarly journals Bromoform-assisted aqueous free radical polymerisation: a simple, inexpensive route for the preparation of block copolymers

2021 ◽  
Author(s):  
Helena Jayne Hutchins-Crawford ◽  
Matthew J Derry ◽  
Padarat Ninjiaranai ◽  
Robert Molloy ◽  
Brian Tighe ◽  
...  
Keyword(s):  
Free Radical ◽  
Block Copolymer ◽  
Block Copolymers ◽  
Mass Distribution ◽  
Molar Mass ◽  
Molecular Composition ◽  
Molar Mass Distribution ◽  
Radical Polymerisation

In the quest for commercially relevant block copolymer additives, for which overall average molecular composition is key but molar mass distribution is of little importance, we present a straightforward, sulfur-...

Determination of chemical composition and molar mass distribution of random styrene-ethyl acrylate copolymers by high-throughput liquid chromatography

e-Polymers ◽  
2005 ◽  
Vol 5 (1) ◽  
Author(s):  
Iván García Romero ◽  
Mubasher Ahmed Bashir ◽  
Harald Pasch
Keyword(s):  
Chemical Composition ◽  
High Throughput ◽  
Molar Mass ◽  
Ethyl Acrylate ◽  
Parallel Synthesis ◽  
Size Exclusion ◽  
Random Copolymers ◽  
Chemical Heterogeneity ◽  
Scanning Calorimetry

AbstractSynthesis and characterization of random copolymers by spectroscopic and chromatographic techniques are normally slow and expensive because most measurements are conducted consecutively and no high-throughput techniques are used. In the present work parallel synthesis and high-throughput analytical techniques for random styrene-ethyl acrylate copolymers were developed. With combinatorial methods, high-throughput instruments and a better design of experiments, the molar mass and chemical composition analyses were carried out simultaneously with time savings of more than 90% as compared to conventional set-ups. The chemical heterogeneity of high-conversion styrene-ethyl acrylate copolymers was determined successfully by fast gradient HPLC. Determination of the average composition was carried out via selective UV detection in size exclusion chromatography. The results were verified by 1H NMR and calculations based on the copolymerisation parameters. Differential scanning calorimetry and optical microscopy techniques were used for determination of the phase separation behaviour of the copolymers and correlated with the chemical heterogeneity.

Fracture Toughness of Large Forgings for Power Producing Industry

2013 ◽  
Vol 577-578 ◽  
pp. 593-596 ◽  
Author(s):  
Václav Mentl
Keyword(s):  
Fracture Toughness ◽  
Chemical Composition ◽  
Steam Turbine ◽  
Mechanical Treatment ◽  
Material Degradation ◽  
The Real ◽  
Operational Safety ◽  
Local Properties ◽  
Thermo Mechanical Treatment ◽  
Shape And Size

The steam turbine rotors represent large components both in radial and axial directions. Their local properties generally differ from one forging to another, or if we compare head and bottom parts of the original ingot, or central and circumferential localities of one rotor body respectively, or if we compare the properties of separate discs e.g. in the case of welded rotors. These differences stem from both even slight changes in the chemical composition (of separate heats or even within one ingot) and thermo-mechanical treatment and in the differences in technology with respect to the real shape and size of the forgings in question. In the paper, the consequences of the differences in fracture toughness characteristics in various rotor localities are discussed with respect to the rotors operational safety taking into account the existence of cracks and material degradation.

Fluorometric and Ultraviolet−Visible Absorption Study of Poly(methacrylic acid) Shells of High-Molar-Mass Block Copolymer Micelles†

Langmuir ◽  
1999 ◽  
Vol 15 (12) ◽  
pp. 4185-4193 ◽  
Author(s):  
Miroslav Štěpánek ◽  
Klára Podhájecká ◽  
Karel Procházka ◽  
Yue Teng ◽  
Stephen E. Webber
Keyword(s):  
Block Copolymer ◽  
Methacrylic Acid ◽  
Molar Mass ◽  
Absorption Study ◽  
Visible Absorption ◽  
High Molar Mass ◽  
Block Copolymer Micelles ◽  
Copolymer Micelles

Interactions in block copolymers in solution: The effect of hetero-contacts on the segmental interactions in block copolymers of poly(isoprene : styrene) in solution

1969 ◽  
Vol 22 (8) ◽  
pp. 1649 ◽  
Author(s):  
JR Urwin
Keyword(s):  
Block Copolymer ◽  
Block Copolymers ◽  
Linear Relation ◽  
Sequence Block ◽  
Cluster Integrals ◽  
Excluded Volumes

Binary cluster integrals or excluded volumes for chemically different segment pairs in block copolymers of poly(isoprene : styrene) have been calculated from the equation derived by Froelich and Benoit for a two- sequence block copolymer. Expansion factors have been recalculated assuming a linear relation for [η]θ with respect to composition employing published values for polystyrene and polyisoprene. The results are discussed in relation to possible conformations of block copolymers.

scholarly journals Characterizing block-copolymer micelles used in nanomedicines via solution static scattering techniques

2021 ◽  
Author(s):  
Isamu Akiba ◽  
Kazuo Sakurai
Keyword(s):  
Block Copolymer ◽  
Block Copolymers ◽  
Static Solution ◽  
Theoretical Background ◽  
Hydrophobic Drugs ◽  
Safety And Efficacy ◽  
Critical Quality Attributes ◽  
Regulatory Authorities ◽  
Block Copolymer Micelles ◽  
Copolymer Micelles

AbstractBlock copolymers are well recognized as excellent nanotools for delivering hydrophobic drugs. The formulation of such delivery nanoparticles requires robust characterization and clarification of the critical quality attributes correlating with the safety and efficacy of the drug before applying to regulatory authorities for approval. Static solution scattering from block copolymers is one such technique. This paper first outlines the theoretical background and current models for analyzing this scattering and then presents an overview of our recent studies on block copolymers.

scholarly journals Predicting the glass transition temperature and viscosity of secondary organic material using molecular composition

2018 ◽  
Vol 18 (9) ◽  
pp. 6331-6351 ◽  
Author(s):  
Wing-Sy Wong DeRieux ◽  
Ying Li ◽  
Peng Lin ◽  
Julia Laskin ◽  
Alexander Laskin ◽  
...  
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Chemical Composition ◽  
Organic Compounds ◽  
Molar Mass ◽  
Solid Phase ◽  
Amorphous Solid ◽  
Semi Solid ◽  
Oxygen Atoms

Abstract. Secondary organic aerosol (SOA) accounts for a large fraction of submicron particles in the atmosphere. SOA can occur in amorphous solid or semi-solid phase states depending on chemical composition, relative humidity (RH), and temperature. The phase transition between amorphous solid and semi-solid states occurs at the glass transition temperature (Tg). We have recently developed a method to estimate Tg of pure compounds containing carbon, hydrogen, and oxygen atoms (CHO compounds) with molar mass less than 450 g mol−1 based on their molar mass and atomic O : C ratio. In this study, we refine and extend this method for CH and CHO compounds with molar mass up to ∼ 1100 g mol−1 using the number of carbon, hydrogen, and oxygen atoms. We predict viscosity from the Tg-scaled Arrhenius plot of fragility (viscosity vs. Tg∕T) as a function of the fragility parameter D. We compiled D values of organic compounds from the literature and found that D approaches a lower limit of ∼ 10 (±1.7) as the molar mass increases. We estimated the viscosity of α-pinene and isoprene SOA as a function of RH by accounting for the hygroscopic growth of SOA and applying the Gordon–Taylor mixing rule, reproducing previously published experimental measurements very well. Sensitivity studies were conducted to evaluate impacts of Tg, D, the hygroscopicity parameter (κ), and the Gordon–Taylor constant on viscosity predictions. The viscosity of toluene SOA was predicted using the elemental composition obtained by high-resolution mass spectrometry (HRMS), resulting in a good agreement with the measured viscosity. We also estimated the viscosity of biomass burning particles using the chemical composition measured by HRMS with two different ionization techniques: electrospray ionization (ESI) and atmospheric pressure photoionization (APPI). Due to differences in detected organic compounds and signal intensity, predicted viscosities at low RH based on ESI and APPI measurements differ by 2–5 orders of magnitude. Complementary measurements of viscosity and chemical composition are desired to further constrain RH-dependent viscosity in future studies.

scholarly journals Engineering block copolymer materials for patterning ultra-low dimensions

2020 ◽  
Vol 5 (10) ◽  
pp. 1642-1657
Author(s):  
Cian Cummins ◽  
Guillaume Pino ◽  
Daniele Mantione ◽  
Guillaume Fleury
Keyword(s):  
Thin Film ◽  
Block Copolymer ◽  
Block Copolymers ◽  
Low Dimensions ◽  
Processing Strategies ◽  
Synthetic Routes ◽  
Film Processing ◽  
Thin Film Processing

Recently engineered high χ-low N block copolymers for nanolithography are evaluated. Synthetic routes together with thin film processing strategies are highlighted that could enable the relentless scaling for logic technologies at sub-10 nanometres.

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