Polystyrene microgel amphiphiles with maltohexaose. Synthesis, characterization, and potential applications

4-Vinylbenzyl maltohexaoside peracetate (1) was copolymerized with divinylbenzene (DVB) using 1-phenyl-1-(2',2',6',6'-tetramethyl-1'-piperidinyloxy)ethane (2) in m-xylene. The copolymerizations were performed at 138 degrees C for 20 h using the mole fraction of 1 in the total feed of 1 and DVB (F1: [1]/[1]+[DVB]) varying from 0.11 to 0.38, affording polymeric products in yields ranging from 32 to 40%. The characterizations by linear PS-calibrated size exclusion chromatography (SEC), dynamic laser light scattering (DLS) measurements, and 1H NMR spectroscopy indicated that the product was assignable to the cross-linked poly(4-vinylbenzyl maltohexaoside peracetate) particle which is able to produce stable solutions, i.e., the PSt microgel with acetyl maltohexaose, 3. The specific rotations ([alpha]D23, c = 1.0 CHCl3) of 3 ranged from +43.3 degrees to +85.6 degrees. The average molar masses determined by the static laser light scattering (SLS) measurement of 3, M(w,SLS)'s, were from 64,700 to 118,000, which were calculated using the respective refractive index increments, dn/dc's, ranging from 0.03387 to 0.08340. The apparent numbers of the 1, 2, and DVB units in 3, N1, N2, and N(DVB), which were estimated from the respective [alpha]D23 values, M(w,SLS)'s, and real yields, ranged from 22 to 35, from 7 to 26, and from 146 to 506, respectively. The deacetylation of 3 was achieved by treatment with sodium methoxide in dry 1,4-dioxane to produce the PSt microgel with maltohexaose as the hydrophilic segment, 4, as a white solid. The solubility of 4 in various solvents was examined, indicating that a hydrophilic property was effectively introduced. Notably, 4 gave clear solutions in the mixed solvent of 1,4-dioxane and H2O. The ability to solubilize fullerite (mixture of fullerenes, C60/C70 = ca. 9/1) in aqueous solutions was examined according to the literature method. Approximately, 100 mg of 4 (1.7 micromol) solubilizes 1.3 mg of fullerite (1.7 micromol).