Star-shaped architecture

Problem 12.13 The combination of RAFT chemistry and the FIDA cydoadditicm provides a simple and synthetically nondemanding pathway to well-de ned macromolecular star-shaped architectures. In support of this contention describe the synthesis of polystyrene (PSt) star polymers with up to 4 arms using the aforesaid two different RAFT end groups, namely, diethoxy-phosphoryldithioformate and pyridin-2-yldithioformate, and HDA coupling reactions. 

Characteristics and Applications of Star-Shaped Architecture for PLA and PGCL... 

In this study, lactide was polymerized by Sn-oct in the presence of polyfunctional alcohols such as glycerol or pentaerythritol. The resulting PLA had multi-armed chains to yield a star-shaped architecture. The microstructure, thermal properties, and degradation behaviour were studied to compare the effect of the different architecture, linear PLA with starshaped one. In addition, it was very beneficial to study the effect of various chain end groups on the thermal and hydrolytic stability of this multi-armed PLA. Therefore, OH terminal groups of PLA were converted into Cl, NH2 or COOH groups. 

The star-shaped architecture was also applied to poly(glycolide-co-e-caprolactone) (PGCL) for developing a flexible monofilament suture. The microstructure, thermal properties, and degradation rate of linear and star-shaped PGCL was studied in terms of the different chain structure. Additionally, the mechanical properties of drawn fibres made of linear and star-shaped PGCL were compared. 

Among the great diversity of fullerene-based macromolecular architectures [1] polymer-stars with a fullerene as the central core have been particularly well studied. Interest in them stems first from the potentialities of these new materials to combine the electronic properties of Ceo vvith the well-known advantages of polymers but also from the opportunities offered by the specific chemical reactivity of this fullerene to build new model star-shaped architectures. 

---