Glycoconjugated polymer.: 4.: Synthesis and aggregation property of well-defined end-functionalized polystyrene with β-cyclodextrin

2,2,6,6-Tetramethylpiperidinyloxy (TEMPO)-substituted beta-cyclodextrin (beta-CyD), 1, was synthesized as the initiator for the nitroxide-mediated living radical polymerization. Styrene (St) was polymerized with 1 using a molar ratio of St and 1 in a feed ([St]/[1]) of 200 at 120 degreesC for 6 h. The size exclusion chromatography (SEC) trace of the product exhibited a symmetrical peak with a weight-average molecular weight (M-w,SEC) of 11400 and a polydispersity (M-w/M-n) of 1.13. In the H-1 NMR spectrum of the product, the signals due to polystyrene (PSt) appeared along with the characteristic signals due to the 1 unit. Thus, the product was assignable to the end-functionalized PSt with acetylated beta-CyD, 2. The introduction of acetylated beta-CyD into 2 was found to occur in a quantitative fashion, which was confirmed by thin-layer chromatography equipped with a flame ionization detector (TLC-FID). For the [St]/[1] of 600 at 120 degreesC, the St/1 system proceeded in a controlled manner to afford 2 with polymerization times of 1.5-9 h with yields of 5-40% and M-w,M-SEC's of 7500-26 000. On the other hand, the St/1 system for 15 and 20 h afforded polymers with 54 and 75% though an unexpected side reaction occurred. Polymer 2 with M-w,SEC'S of 7500-26 000 was modified by deacetylation using sodium methoxide in dry THF into end-functionalized PSt with beta-CyD, 3. Particle formation was observed during dynamic laser light scattering measurements of 3 in benzene, indicating that 3 was stably suspended in a good solvent for PSt by forming aggregates with beta-CyD as a core. The average aggregation numbers (N-A) of the aggregates were found to range from 42 to 125, which were determined by static laser light scattering measurement.