142 Advances in Polymer Science Editorial Board: A. Abe. A.-C ...

Asymmetric Star Polymers: Synthesis and Properties
Nikos Hadjichristidis, Stergios Pispas, Marinos Pitsikalis, Hermis Iatrou and
Costas Vlahos
Department of Chemistry, University of Athens, Panepistimiopolis, Zografou, 15771 Athens,
Greece E-mail: nhadjich@atlas.uoa.gr
The synthesis and the properties, both in bulk and in solution, of asymmetric star polymers
are reviewed. Asymmetry is introduced when arms of different molecular weight, chemical
nature or topology are incorporated into the same molecule. The phase separation, aggregation
phenomena, dilute solution properties etc. are examined from a theoretical and experimental
point of view. Recent applications of these materials show their importance in
modern technologies.
Keywords. Asymmetry, Miktoarm stars, Synthesis, Morphology, Aggregation, Chain conformation
List of Symbols and Abbrevations . . . . . . . . . . . . . . . . . . . . . . . 72
1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
2 Synthesis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
2.1 Stars with Molecular Weight Asymmetry . . . . . . . . . . . . . . 75
2.2 Stars with Chemical Asymmetry . . . . . . . . . . . . . . . . . . . 78
2.2.1 Miktoarm Stars . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
2.2.1.1 General Strategies and Methods . . . . . . . . . . . . . . . . . . . 78
2.2.1.2
2.2.1.3
2.2.1.4
2.2.1.5
2.2.1.6
2.2.1.7
Synthesis of A2B Miktoarm Star Copolymers . . . . . . . . . . . .
Synthesis of A3B Miktoarm Star Copolymers . . . . . . . . . . . .
Synthesis of AnB (n>5) Miktoarm Star Copolymers . . . . . . . .
Synthesis of A2B2 Miktoarm Star Copolymers . . . . . . . . . . .
Synthesis of AnBn (n>2) Miktoarm Star Copolymers . . . . . . .
Synthesis of ABC Miktoarm Star Terpolymers . . . . . . . . . . .
82
85
85
88
89
93
2.2.1.8 Synthesis of ABCD Miktoarm Star Quaterpolymers . . . . . . . . 96
2.2.2 Asymmetric w-Functionalized Polymers . . . . . . . . . . . . . . 97
2.3 Stars with Topological Asymmetry . . . . . . . . . . . . . . . . . . 98
3 Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100
3.1 Solution Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . 100
3.1.1 Theory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100
3.1.2 Experimental Results . . . . . . . . . . . . . . . . . . . . . . . . . . 104
3.2 Bulk Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
Advances in Polymer Science, Vol.142
© Springer-Verlag Berlin Heidelberg 1999