Copolymers, graft comb-type synthesis

Synthesis of poly(L-lysine)-grafted hyaluronic acid (PLL-g-HA) comb-type copolymers has recently been described. HA chains were covalently coupled at the E-amino groups of polylysine by reductive amination reaction (66). These PLL-g-HA derivatives were shown to form complexes with plasmid DNA. The complex showed stability against nuclease degradation and was internalized by liver cells (67-70). 

The use of macromonomers in controlled living polymerization techniques, such as ionic or CRP, is at present the preferred synthesis strategy for the preparation of relatively well-defined graft copolymers. Macromonomers are oligomers fitted with polymerizable end-groups, mainly styrenic or (meth)acrylic, that can copolymerize with monomers to form comb-type graft copolymers with pendent preformed polymer chains. 

One of the primary thrusts in oligomeric research has been in developing oligomers as intermediates in preparative polymer chemistry. The chemistry of chain-ended functional oligomers is important to preparative polymer chemistry because of their use as macromonomers, telechelics and any other type of reactive oligomer. Macromonomers have been used as precursors for the synthesis of graft copolymers, comb-like polymers and networks. Telechelics have been used primarily to synthesize block copolymers," polymer networks and interpenetrating polymer networks. 

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