A novel amphiphilic block copolymer functionalized with strong push-pull azobenzene moieties
P(HEMA-
b
-6CNAzo)
was synthesized by using ATRP. First
the macromolecular initiator P(HEMA-TMS) was prepared through ATRP reaction of monomer HEMA-TMS
which was hydroxylethyl-mathacrylate (HEMA) protected with trimethylsilane (TMS) groups. Then
the precursor diblock copolymer
P(HEMA-TMS-
b
-6MA)
containing aniline groups was prepared by a P(HEMA-TMS)-initiated ATRP of 6-(N-methylanilino)hexyl methacrylate. The amphiphilic azo block copolymer
P(HEMA-
b
-6CNAzo)
was obtained by azo-coupling reaction between P(HEMA-TMS-
b
-6MA) and diazonium salt of 4-aminobenzonitrile and the TMS groups were removed at the same time because of the acidic conditiond. The macro-initiator and block copolymers were characterized by GPC
1
H-NMR and UV-vis. GPC results showed that both P(HEMA-TMS) and P(HEMA-TMS-
b
-6MA) had narrow molecular weight distributions.
1
H-NMR analysis indicated that the ratio of polymerization degree for HEMA andP6MA blocks is 0.95∶1. The conversion rate of azo-coupling reaction and hydrolysis of TMS groups were close to 100%. By adding deionized water under a rate of 1μL/s to a THF solution of P(HEMA-
b
-6CNAzo) with the concentration of 0.2g/L
the amphiphilic block copolymers self-assembled to form colloidal spheres with sizes in range from 60 and to 80nm.