(State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Material Science and Engineering, Donghua University, Shanghai 201620, China)
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DOI:
10.7502/j.issn.1674-3962.2013.06.05
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Abstract:
The amphipathic block copolymer poly(t-butyl acrylate)-b-poly(2-dimethylamino)ethyl methacrylate (PtBA-b-PDMAEMA) was synthesized via sequential atom transfer radical polymerization (ATRP), and PtBA-b-PDMAEMA micelles were prepared by adding the selective-solvent water into the cosolvent THF solution. The shell cross-linking micelles (SCL micelle) were obtained by cross-linking PDMAEMA using 1, 2-bis-(2-iodoethoxy) ethane (BIEE) as a cross-linker. The structure and morphology of the SCL micelle were investigated by means of 1H NMR, dynamic light scattering (DLS) and transmission electron microscopy (TEM). The effect of molar ratio of BIEE to PDMAEMA ([BIEE]/[PDMAEMA]) on the cross-linking network structure was investigated in detail. It was found that intra-micelle cross-linking tended to be formed when [BIEE]/[PDMAEMA] ratio was lower than 0.5, and the spherical SCL micelles were obtained. When the ratio was higher than 0.5, inter-micelle cross-linking structure would be obtained, which increased the hydrodynamic diameters of the SCL micelles. In addition, the pH/ thermo-responsive behaviors of the SCL micelles were studied. The SCL micelles showed reversible collapse and stretch with the changes of temperature and pH of the medium, and could be good carriers for drug controlled release system.