Influence of Different Inorganic Salts on Crystallization-driven Morphological Transformation of PCL-b-PEO Micelles in Aqueous Solutions

Different inorganic salts, including NaSCN, NaCl, MgCl2 and Na2SO4, were added into the aqueous solution containing poly（ε-caprolactone）-b-poly（ethylene oxide） （PCL-b-PEO） semicrystalline mieelles. The effects of inorganic salt on the micellar size and morphology were investigated with TEM and DLS....

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Published inChinese journal of polymer science Vol. 32; no. 9; pp. 1128 - 1138
Main Authors Yang, Jie-xin, He, Wei-na, Xu, Jun-ting, Du, Bin-yang, Fan, Zhi-qiang
Format Journal Article
LanguageEnglish
Published Heidelberg Chinese Chemical Society and Institute of Chemistry, CAS 01.09.2014
Subjects
Anions
Aqueous solutions
Asymptotic properties
Cations
Characterization and Evaluation of Materials
Chemistry
Chemistry and Materials Science
Condensed Matter Physics
Industrial Chemistry/Chemical Engineering
Inorganic salts
Micelles
Oxides
Polymer Sciences
Transformations
形态转变
无机盐
氯化镁
水溶液
硫氰酸钠
结晶
胶束
驱动
Micelle
Inorganic salt
Block copolymer
Crystallization
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Summary:Different inorganic salts, including NaSCN, NaCl, MgCl2 and Na2SO4, were added into the aqueous solution containing poly（ε-caprolactone）-b-poly（ethylene oxide） （PCL-b-PEO） semicrystalline mieelles. The effects of inorganic salt on the micellar size and morphology were investigated with TEM and DLS. It is found that addition of NaSCN leads to increase of the micellar size, but the micelles remain to be spherical. By contrast, the other three inorganic salts can induce sphere-to-cylinder or sphere-to-lamella transformations of the PCL-b-PEO semicrystalline mieelles. The alteration rate of the micellar size with the time after addition of the inorganic salts decreases in the following order： NazSO4 〉 NaCl ≈ MgCl2〉 NaSCN. These results were interpreted in terms of the ＂salting-out＂ ability of the cations and anions. The anions SO42- and Cl- have a stronger ＂salting-out＂ ability, driving the morphological transformations of the micelles and leading to a rapid change in micellar size. By contrast, SCN- has a weaker salting-out＂ ability. The cations Na＋ and Mg2＋ may associate with the PEO blocks, leading to a ＂salting-out＂ effect as well. However, the ＂salting-out＂ ability of cations is weaker than that of SO42- and Cl- anions, and the ＂salting-out＂ abilities ofNa＋ and Mg2＋ are similar.
Bibliography:Block copolymer; Crystallization; Inorganic salt; Micelle.
Different inorganic salts, including NaSCN, NaCl, MgCl2 and Na2SO4, were added into the aqueous solution containing poly（ε-caprolactone）-b-poly（ethylene oxide） （PCL-b-PEO） semicrystalline mieelles. The effects of inorganic salt on the micellar size and morphology were investigated with TEM and DLS. It is found that addition of NaSCN leads to increase of the micellar size, but the micelles remain to be spherical. By contrast, the other three inorganic salts can induce sphere-to-cylinder or sphere-to-lamella transformations of the PCL-b-PEO semicrystalline mieelles. The alteration rate of the micellar size with the time after addition of the inorganic salts decreases in the following order： NazSO4 〉 NaCl ≈ MgCl2〉 NaSCN. These results were interpreted in terms of the ＂salting-out＂ ability of the cations and anions. The anions SO42- and Cl- have a stronger ＂salting-out＂ ability, driving the morphological transformations of the micelles and leading to a rapid change in micellar size. By contrast, SCN- has a weaker salting-out＂ ability. The cations Na＋ and Mg2＋ may associate with the PEO blocks, leading to a ＂salting-out＂ effect as well. However, the ＂salting-out＂ ability of cations is weaker than that of SO42- and Cl- anions, and the ＂salting-out＂ abilities ofNa＋ and Mg2＋ are similar.
11-2015/O6
ObjectType-Article-1
SourceType-Scholarly Journals-1
ObjectType-Feature-2
content type line 23
ISSN:0256-7679
1439-6203
DOI:10.1007/s10118-014-1512-z