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30–40 nm which is in sharp contrast to vesicular assembly formed
by P2. The hydrodynamic diameter (DH) estimated by DLS
studies (Fig. 3c) was found to be 30 Æ 10 nm which is in good
agreement with TEM results. Micelle formation was further
supported by the ability of P3 solution to encapsulate the
hydrophobic guest pyrene (I1/I3 = 1.26) (Fig. 3d). However when
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band around 534 nm due to the R6G dye could be seen (Fig. S5,
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any vesicular assembly. Moreover aqueous solution of P3 did not
show any LCST. Thus based on these control experiments it can
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key factor for unprecedented vesicle formation and thermo-
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We have demonstrated spontaneous vesicular assembly from
a thermo-responsive amphiphilic random copolymer consisting
of methacrylate-type hydrophobic and methacrylamide-type
hydrophilic repeat units. Above a CMTT (which is close to
the LCST of the polymer) the vesicular assembly was reversibly
converted to micelle-type aggregates. Control experiments sug-
gested that the amide groups in the polymer backbone are
responsible for unprecedented stimuli-responsive behavior from
a remarkably simple random copolymer. Currently we are
engaged in chemical modification of the vesicular surface with
appropriate ligand moieties and tuning the CMTT (preferably
bringing it down to B40 1C) by adjusting the hydrophobic/
hydrophilic segments for taking this remarkably simple polymer
to the biomedical domain as a targeted drug-delivery vehicle.14
We thank CSIR for financial support (01(2366)/10/EMR-II).
KD thanks CSIR for research fellowship.
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c
This journal is The Royal Society of Chemistry 2011
Chem. Commun., 2011, 47, 12491–12493 12493