AP-GAC

SYNTHESIS AND SELF-ASSEMBLY OF POLYPHOSPHAZENE (PP) BLOCK COPOLYMERS. DESIGN OF NEW INORGANIC NANOSTRUCTURES DERIVED FROM HIGH CRISTALLINE OR/AND CHIRAL HIGH TUNABLE PP BLOCK

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 Obiettivo del progetto (Objective)

'An exciting new area would involve PP block copolymers. These materials would possess an inorganic PP coblock which is superficially reminiscent of Polysiloxane. However, the PP block is inherently much more tunable. A key advantage is that whereas siloxane blocks are intrinsically highly hydrophobic, phosphazene blocks can be easily derivatized to allow them to become hydrophilic. This has the key advantage that self-assembly can be performed in water making processing and practical applications more realistic. This tunability of phosphazene blocks, will allow us to gain deep insight into the factors that facilitate self-assembly of block copolymers in solution and will also allow us to access stabilized nanomaterials for example by introducing crosslinking groups. The introduction of high crystallinity and/or chirality in the PP block will allow us to generate novel and interesting nanostructures.'

Introduzione (Teaser)

Block copolymers (BCPs) are a versatile class of materials formed by repeating chemical blocks that are simple monomers or complex polymers. New formulations have resulted in self-assembly of many novel nanostructures.

Descrizione progetto (Article)

Much like metal alloys or composite materials that combine the strengths of individual components for a superior blend, BCPs make possible a wide array of properties. EU-funded scientists working on the project AP-GAC explored the potential inherent in self-assembly of polyphosphazene-based BCPs into interesting nanostructured compounds.

Polyphosphazene BCPs consist of alternating phosphorous and nitrogen atoms. They are highly tuneable and hundreds have been synthesised with various side groups bound to the phosphorous atoms since the first reported approximately 15 years ago. AP-GAC focused on preparation of BCPs consisting of only two blocks (diblock), either two different polyphosphazenes or a hybrid BCP consisting of a polyphosphazene and a polystyrene.

The team successfully prepared BCPs consisting of two different polyphosphazene BCPs. Synthesis of the diblock required blocking an initiator to prevent triblock formation through bi-directional chain growth. Using their techniques, investigators delivered the first chiral polyphosphazene BCPs with chemical functionalities randomly distributed in one block. A number of interesting nanostructured architectures were created from the BCPs including chiral twisted nanostructures, vesicles, nanospheres and mesoporous films.

With novel macroinitiators prepared by the project team, scientists synthesised hybrid BCPs consisting of one polyphosphazene block and one polystyrene block. Both blocks were synthesised via living polymerisation, chain growth in which the ability of a growing polymer to terminate has been removed. The team used these hybrid BCPs to create nanospheres, multi-compartmental micelles, donut-shaped micelles and cylinder networks by changing the concentration of the polymers.

AP-GAC successfully achieved all research goals with demonstration of self-assembly of diblock BCPs based on polyphosphazene and created a variety of novel nanostructures. Results have been widely published. They should spur innovation both into potential applications of these novel materials as well as into additional materials to be prepared with similar techniques.