Lower Critical Solution Temperature in Poly( N ‐Isopropylacrylamide): Comparison of Detection Methods and Molar Mass Distribution Influence

The molecular weight dependence of the lower critical solution temperature of poly(N,N-diethylacrylamide) was studied with 11 samples of the polymer with a number-average molecular weight (Mn) ranging from 9.6 × 103 to 1.3 × 106 g mol1 and relatively narrow polydispersity indices from 1.19 and 2.60. These samples were obtained by fractional precipitation of the polymer. LCST values of polymers were measured by turbidimetry and microcalorimetry. An inverse dependence of LCST on the molar mass was found and the LCST of the samples remained more or less a constant above a critical molecular weight of ca. 2 × 105 g mol1. The enthalpy and the entropy changes as well as the LCST of the polymer depend strongly on the molar mass of the polymer, especially in low molecular weight range.Key words: poly(N,N-diethylacrylamide), LCST, thermosensitive, phase diagram, effect of molecular weight.

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Applying Phase Separation of a Solvent System with a Lower Critical Solution Temperature for Enhancement of Cooling Rates by Forced and Free Convection

Proceedings of the 15th International Heat Transfer Conference ◽

10.1615/ihtc15.hte.008983 ◽

2014 ◽

Cited By ~ 1

Author(s):

Amos Ullmann ◽

Itay Lipstein ◽

Neima Brauner

Keyword(s):

Phase Separation ◽

Free Convection ◽

Lower Critical Solution Temperature ◽

Solvent System ◽

Solution Temperature ◽

Cooling Rates ◽

Critical Solution Temperature

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QELSS diffusion data for moderately broad molar mass distribution polymer samples compared with data from classical gradient techniques

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19891821 ◽

1989 ◽

Vol 54 (7) ◽

pp. 1821-1829

Author(s):

Bedřich Porsch ◽

Simon King ◽

Lars-Olof Sundelöf

Keyword(s):

Diffusion Coefficient ◽

Mass Distribution ◽

Molar Mass ◽

Molar Mass Distribution ◽

Diffusion Data ◽

Mass Distributions ◽

Classical Diffusion ◽

Polydisperse Polymer

The differences between the QELSS and classical diffusion coefficient of a polydisperse polymer resulting from distinct definitions of experimentally accessible average values are calculated for two assumed specific forms of molar mass distributions. Predicted deviations are compared with the experiment using NBS 706 standard polystyrene. QELSS Dz of this sample relates within 2-4% to the classical diffusion coefficient, if the Schulz-Zimm molar mass distribution is assumed to be valid. In general, differences between the height-area and QELSS diffusion coefficient of about 20% may be found for Mw/Mn ~ 2, and this value may increase above 35%, if strongly tailing molar mass distribution pertains to the sample.

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A polyelectrolyte-containing copolymer with a gas-switchable lower critical solution temperature-type phase transition

Polymer Chemistry ◽

10.1039/c8py01265b ◽

2019 ◽

Vol 10 (2) ◽

pp. 260-266 ◽

Cited By ~ 4

Author(s):

Jin-Jin Li ◽

Yin-Ning Zhou ◽

Zheng-Hong Luo ◽

Shiping Zhu

Keyword(s):

Phase Transition ◽

Cloud Point ◽

Lower Critical Solution Temperature ◽

Solution Temperature ◽

Critical Solution Temperature ◽

Type Phase

A polyelectrolyte-containing copolymer with a CO2/N2-switchable cloud point, resulting from the gas-induced alternation of hydrophilicity, was prepared.

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