Preparation of low molecular weight cyclic polystyrenes with high purity via liquid chromatography at the critical condition

다국어 초록 (Multilingual Abstract)

<P><B>Abstract</B></P> <P>Cyclic polymers synthesized by ring-closure method from linear precursors contain some of linear contaminates. In this work, the origin of linear contaminates in cyclic polystyrenes (<I>c</I>-PS) is demonstrated by the coupling of liquid chromatography at the critical condition (LCCC) with matrix-assisted laser desorption/ionization time-of-flight mass spectra. The linear contaminates are revealed to be the “dead” chains during ATRP by chain termination, the unreacted linear polystyrene (<I>l</I>-PS) precursors, and the dimers by the imperfect ring-closure reaction. The <I>c</I>-PS are purified by LCCC fractionation, and the results show the LCCC fractionation at the critical adsorption point (CAP) of <I>c</I>-PS is more efficient than that at the CAP of linears for low molecular weight (<10,000) PS. A two-step LCCC method is presented for the preparation of <I>c</I>-PS with high purity (>99.6%) via the tandem-coupled LCCC fractionation at the CAP of <I>l</I>-PS and at the CAP of <I>c</I>-PS.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The linear contaminates in cyclic polystyrenes (<I>c</I>-PS) were identified. </LI> <LI> The LCCC fractionation at the CAP of <I>c</I>-PS is very efficient. </LI> <LI> Highly purified <I>c</I>-PS were obtained by a tandem-coupled LCCC fractionation method. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>