ABSTRACT:Macrocyclic polystyrenes with various molecular weight were prepared by the reaction of linear polystyrene having two end vinyl groups and potassium naphthalenide as a coupling agent. Intermolecular side reactions produced higher molecular weight polycondensates and undesirable chain termination reactions also produced linear precursors in addition to the designed molecules. In order to isolate cyclic polymers from the ring closure reaction mixtures, preparative size exclusion chromatography (SEC) method was employed. The purity of SEC-fractionated cyclic polystyrenes was rigorously examined by liquid chromatography at the critical condition (LCCC) and interaction chromatography (IC). After SEC-fractionation, we obtained large amount of highly pure cyclic polymers, though high molecular weight cyclic polymers contain very small amount of linear precursor (< 5%). The purity and isotope effect on reversed-phase liquid chromatography (RPLC) were also rigorously investigated by preparing a deuterated cyclic polystyrene. [DOI 10.1295/polymj.37.506] KEY WORDS Cyclic Polystyrene / GPC Fractionation / LCCC / Isotope Effect / Cyclic macromolecules are of great interest in the investigation of the influence of cyclization on their solution, melt, and solid-state properties. Various physical properties of cyclic polymers have been predicted not only by theoretical methods 1-4 but also by computer simulation studies, 5-7 while they have also been examined experimentally. [8][9][10][11][12][13][14] Cyclic polymers were usually synthesized by the coupling reaction between living precursor polymers with functional groups on both ends and bifunctional linking agents. For example, polystyrenes 9,15-19 and poly(2-vinylpyridine)s 20,21 have been synthesized by this method. Furthermore, , !-heterobifunctional polymers have been used for the synthesis of cyclic polymers.22-24 However, side reactions produce linear precursor polymers, and intermolecular reactions simultaneously produce dimeric and higher molecular weight linear polycondensates. Therefore, it is very difficult to obtain pure cyclic polymers directly, and fractionation is necessary in order to obtain cyclic polymers with high purity. For the isolation of cyclic polymers from the ring closure reaction mixtures, two major fractionation methods have been employed: fractional precipitation method 9,14,[16][17][18] and preparative size exclusion chromatography (SEC). 25,26 Furthermore, liquid chromatography at the critical condition method (LCCC) has been successfully applied for the characterization of cyclic polymers.27-30 Throughout these experimental studies, however, the direct evidence of cyclic structure was not shown, in addition to the fact that the purity of the cyclic molecules has not been determined quantitatively in most of the works. Only for the low molecular weight cyclic polymers, the detailed cyclic structures were directly confirmed by NMR analysis of linking points, 22,23 pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS), 31 and matri...

Polystyrene (PS) bilayers were prepared and were adhered at a temperature between the surface and bulk glass-transition temperatures for a given time. Then, the interfacial adhesion strength (G L ) was examined with a conventional lapshear measurement. G L first increased with increasing adhesion time and then reached a constant value. This result implied that the segments moved across the interface, to a certain depth, even at a temperature below the bulk glass-transition temperature. To confirm this, the interfacial evolution for the PS/deuterated PS bilayers was examined with dynamic secondary-ion mass spectrometry. The G L value was linearly proportional to the thickness of the interfacial adhesion layer. Finally, we propose a strategy for regulating the adhesion strength based on the chain-end chemistry.