Liquid chromatography at critical conditions (LCCC) - Chemical heterogeneity of polyethylene oxides

2022 ◽  
Keyword(s):  
Liquid Chromatography ◽  
Critical Conditions ◽  
Chemical Heterogeneity ◽  
Polyethylene Oxides

scholarly journals Separation of Poly(styrene-block-t-butyl methacrylate) Copolymers by Various Liquid Chromatography Techniques

2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
Tina Šmigovec Ljubič ◽  
David Pahovnik ◽  
Majda Žigon ◽  
Ema Žagar
Keyword(s):  
Liquid Chromatography ◽  
Block Copolymers ◽  
Molar Mass ◽  
Small Difference ◽  
Reversed Phase ◽  
Butyl Methacrylate ◽  
Critical Conditions ◽  
Chromatographic Techniques ◽  
Methacrylate Copolymers ◽  
Gradient Liquid Chromatography

The separation of a mixture of three poly(styrene-block-t-butyl methacrylate) copolymers (PS-b-PtBMA), consisting of polystyrene (PS) blocks of similar length andt-butyl methacrylate (PtBMA) blocks of different lengths, was performed using various chromatographic techniques, that is, a gradient liquid chromatography on reversed-phase (C18 and C8) and normal-phase columns, a liquid chromatography under critical conditions for polystyrene as well as a fully automated two-dimensional liquid chromatography that separates block copolymers by chemical composition in the first dimension and by molar mass in the second dimension. The results show that a partial separation of the mixture of PS-b-PtBMA copolymers can be achieved only by gradient liquid chromatography on reversed-phase columns. The coelution of the two block copolymers is ascribed to a much shorter PtBMA block length, compared to the PS block, as well as a small difference in the length of the PtBMA block in two of these copolymers, which was confirmed by SEC-MALS and NMR spectroscopy.

Characterization of Polystyrene-block-Poly(2-vinyl pyridine) Copolymers and Blends of Their Homopolymers by Liquid Chromatography at Critical Conditions

2019 ◽  
Vol 52 (20) ◽  
pp. 7688-7695 ◽  
Author(s):  
Rabia Khatoon ◽  
Sana Rahim ◽  
Rubina Abdul-Karim ◽  
Syed Ghulam Musharraf ◽  
Muhammad Imran Malik
Keyword(s):  
Liquid Chromatography ◽  
Critical Conditions ◽  
Vinyl Pyridine
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