Association behaviors of dodecyltrimethylammonium bromide with double hydrophilic block co-polymer poly(ethylene glycol)-block-poly(glutamate sodium).
The association behaviors of single-chain surfactant dodecyltrimethylammonium bromide (DTAB) with double hydrophilic block co-polymers poly(ethylene glycol)-b-poly(sodium glutamate) (PEG(113)-PGlu(50) or PEG(113)-PGlu(100)) were investigated using isothermal titration microcalorimetry, cryogenic transmission electron microscopy, circular dichroism, ζ potential, and particle size measurements. The electrostatic interaction between DTAB and the oppositely charged carboxylate groups of PEG-PGlu induces the formation of super-amphiphiles, which further self-assemble into ordered aggregates. Dependent upon the charge ratios between DTAB and the glutamic acid residue of the co-polymer, the mixture solutions can change from transparent to opalescent without precipitation. Dependent upon the chain length of the PGlu block, the mixture of DTAB and PEG-PGlu diblocks can form two different aggregates at their corresponding electroneutral point. Spherical and rod-like aggregates are formed in the PEG(113)-PGlu(50)/DTAB mixture, while the vesicular aggregates are observed in the PEG(113)-PGlu(100)/DTAB mixture solution. Because the PEG(113)-PGlu(100)/DTAB super-amphiphile has more hydrophobic components than that of the PEG(113)-PGlu(50)/DTAB super-amphiphile, the former prefers forming the ordered aggregates with higher curvature, such as spherical and rod aggregates, but the latter prefers forming vesicular aggregates with lower curvature.
Beijing National Laboratory of Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, People's Republic of China.
Yuchun
Y
Han
Lin
L
Xia
Linyi
L
Zhu
Shusheng
S
Zhang
Zhibo
Z
Li
Yilin
Y
Wang
D057927:Hydrophobic and Hydrophilic Interactions; D011092:Polyethylene Glycols / Q000737:chemistry*; D011099:Polyglutamic Acid / Q000737:chemistry*; D000644:Quaternary Ammonium Compounds / Q000737:chemistry*
D000644:Quaternary Ammonium Compounds; C013912:decyltrimethylammonium; D011099:Polyglutamic Acid; D011092:Polyethylene Glycols