Copolymer tadpole

Tadpole polymers are polymers consisting of one cyclic chain and one or more linear chains. Quirk and Ma182 prepared a tadpole copolymer consisting of a cyclic PBd and two linear PS chains. First they reacted PDPPE with two monofunctional living PS chains. The resulting difunctional PS was used to initiate the polymerization of butadiene. The living PBd chains were then cyclized with dichlorodimethylsilane in benzene as shown in Scheme 91. The separation of the tadpole copolymer from the polycondensates was achieved by fractional precipitation. 

Let s compare Figure C5.2 and 4.8. You can easily spot the similarity between the structures that tadpoles form in water and those appearing in block-copolymer melts. This is not a coincidence. Indeed, block-copolymers are also amphiphilic molecules, just like the tadpoles . The only difference is that, instead of a tail and a head, they simply have two tails connected with each other. 

Zhao and coworkers reported the synthesis of single-chain tadpoles as shape amphiphiles. The tadpole particles were synthesized from a block copolymer precursor, containing a hydrophobic polystyrene block attached to a hydrophilic poly(2-(dimethylamino)ethyl methacrylate) (DMAEMA) block. The DMAEMA block was collapsed using a quaternization reaction of the tertiary amine with a diiodo cross-linker. The self-assembly of these tadpole-shaped structures was then studied in various polar and non-polar solvents. These and other single-chain tadpoles represent nanoscale architectures with multiple functionalities and controlled three-dimensional structure. 

Njikang, G., Liu, G.J., and Curda, S.A. (2008b) Tadpoles from the intramolecular photo-cross-linking of diblock copolymers. Macromolecules, 41,5697-5702. 

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