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Effect of Hydrophilic Shells on the Formation of Colloidal Crystals by Monodisperse Core‐Shell Polymer Microspheres
Author(s) -
Meng Qingbin,
Li Zhanyong,
Li Gang,
Zhu Xiao Xia
Publication year - 2007
Publication title -
macromolecular rapid communications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.348
H-Index - 154
eISSN - 1521-3927
pISSN - 1022-1336
DOI - 10.1002/marc.200700295
Subject(s) - dispersity , colloid , materials science , chemical engineering , polystyrene , copolymer , shell (structure) , polymer chemistry , polymer , colloidal crystal , polystyrene sulfonate , polyacrylamide , core (optical fiber) , acrylic acid , emulsion , pulmonary surfactant , composite material , pedot:pss , engineering
We have found that a soft, hydrophilic shell is necessary in the formation of three‐dimensional colloidal crystals by polymeric microspheres prepared by surfactant‐free emulsion copolymerization. The core‐shell microspheres contain a hard, hydrophobic polystyrene core and a soft, hydrophilic shell made of polyacrylamide or poly(acrylic acid) (PAA). Dilution of the particles induced a red shift of the diffraction peak. We have found a pH switching effect for the formation of colloidal crystals by the microspheres with a PAA shell. When the carboxylic‐acid groups are protonated, the colloidal crystals lose their order. The same effect is observed when a poor solvent is added to the colloidal crystals formed by the microspheres with a polyacrylamide shell.