Polystyrene Microgel Amphiphiles with Maltohexaose.Synthesis,Characterization,and Potential Applications

摘要

4-Vinylbenzyl maltohexaoside peracetate (1) was copolymerized with divinylbenzene (DVB) using 1-phenyl-l-(2',2',6',6'-tetramethyl-1'-piperidinyloxy)ethane (2) in m-xylene.The copolymerizations were performed at 138 deg C for 20 h using the mole fraction of 1 in the total feed of 1 and DVB (F_1: [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]_D~(23),c = 1.0 CHCl_3) of 3 ranged from +43.3 deg to +85.6 deg .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,N_1,N_2,and N_(DVB),which were estimated from the respective [alpha]_D~(23) 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 H_2O.The ability to solubilize fullerite (mixture of fullerenes,C_(60)/C_(70) = ca.9/1) in aqueous solutions was examined according to the literature method.Approximately,100 mg of 4 (1.7 mumol) solubilizes 1.3 mg of fullerite (1.7 mu mol).