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Characterisation of poly( N ‐isopropylacrylamide) by asymmetrical flow field‐flow fractionation, dynamic light scattering, and size exclusion chromatography
Author(s) -
Yohannes Gebrenegus,
Shan Jun,
Jussila Matti,
Nuopponen Markus,
Tenhu Heikki,
Riekkola MarjaLiisa
Publication year - 2005
Publication title -
journal of separation science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.72
H-Index - 102
eISSN - 1615-9314
pISSN - 1615-9306
DOI - 10.1002/jssc.200401880
Subject(s) - molar mass , dynamic light scattering , light scattering , multiangle light scattering , size exclusion chromatography , field flow fractionation , chain transfer , analytical chemistry (journal) , poly(n isopropylacrylamide) , polymer , chemistry , chromatography , particle size , scattering , fractionation , polymerization , materials science , radical polymerization , optics , organic chemistry , nanoparticle , copolymer , nanotechnology , physics , enzyme
Asymmetrical flow field‐flow fractionation (AsFlFFF) was used to determine the hydrodynamic particle sizes, molar masses, and phase transition behaviour of various poly( N ‐isopropylacrylamide) (PNIPAM) samples synthesised by reversible addition–fragmentation chain transfer (RAFT) and conventional free radical polymerisation processes. The results were compared with corresponding data obtained by dynamic light scattering (DLS) and size exclusion chromatography (SEC). Agreement between the three methods was good except at higher molar masses, where the molar mass averages obtained by SEC were much lower than those obtained by AsFlFFF and light scattering. The aggregation of the polymers, which are thermally sensitive, was studied by DLS and AsFlFFF at various temperatures. In deionised water there was an abrupt change in the particle size due to phase separation at ≈32–35°C. The critical temperatures determined by AsFlFFF were 3–5°C higher than those obtained by DLS.