Fabrication of Mesoporous Polymeric Micelles and Their
Application in Hg2+ Detection
Ju, YY (Ju, Yuan-yuan)[ 1 ] ; Han, GD (Han, Guang-da)[ 1 ] ; Lu, Y (Lu, Yan)[ 2 ] ; Zhao, HY (Zhao, Han-ying)[ 1 ]
ACTA POLYMERICA SINICA, 2018, 8: 1081-1088
DOI: 10.11777/j.issn1000-3304.2018.18009
WOS:000451757500010
Abstract
Amphiphilic
macromolecular brushes with pH-responsiveness and reduction responsiveness were
synthesized by reversible addition-fragmentation chain transfer polymerization
and atom transfer radical polymerization. The side chains of the brush polymers
were covalently connected to the backbones through redox-responsive disulfide
bonds. The structure, molecular weight and molecular weight distribution of the
brush polymers were characterized by H-1-NMR and gel permeation chromatography.
At pH = 10.0, the amphiphilic brush polymers self-assembled into multi-component
micelles with POEGMA shells and PtBMA/PDMAEMA cores. In the cores, the two
hydrophobic blocks segregated into distinct domains due to their
incompatibility, and the hydrophilic POEGMA blocks formed the coronae to
stabilize the structures. The PtBMA chains with larger volume percentage formed
the continuous phases, while the PDMAEMA chains with smaller volume percentage
formed the discontinuous phases. At pH = 4.0, protonated PDMAEMA chains were
highly stretched and formed the coronae of the micelles. Excessive reductant
was added into the micellar solution to reduce the disulfide bonds between
PDMAEMA side chains and the backbones, and mesoporous polymeric micelles with
thiol groups inside the pores were obtained. H-1-NMR results of multi-component
micelles, before and after treatment with the reductant, indicated that the
PDMAEMA side chains were removed completely. Transmission electron microscopy
(TEM) and dynamic light scattering were used to characterize the morphology and
the size of the micelles. Based on TEM results, the average size of the pores
in the micelles was about 2 nm, which was consistent with the average size of
the PDMAEMA discontinuous phases. After the cleavage of the disulfide bonds and
the removal of PDMAEMA chains from the micelles, thiol groups were produced on
the walls of the pores. The thiol groups can be used as reducing agent and
stabilizer in the in situ synthesis of gold nanoparticles. By thiol-bromine
reactions, mesoporous micelles with polythiophene derivatives inside the pores
were synthesized. The micelles showed high sensitivity and excellent
selectivity for Hg2+.
