Swati De

Efficient synthesis of multifunctional polymers via thiol–epoxy “click” chemistry

We demonstrate high efficiency and simplicity of the thiol-epoxy reaction towards preparation of a wide range of main-chain as well as end-chain multifunctional polymers.

Facile and General Preparation of Multifunctional Main-Chain Cationic Polymers through Application of Robust, Efficient, and Orthogonal Click Chemistries

Poly(ß-hydroxyl amine)s are prepared from readily available small molecular building blocks at ambient conditions. These macromolecules can be transformed into main-chain cationic polymers upon quaternization of the backbone amine units. The modular and mild nature of the synthesis allows for incorporation of multiple (2-4) chemically distinct reactive sites in the polymer chain. Modifications of the reactive sites afford multifunctional polymers with tunable properties. The orthogonal nature of the involved chemistries sets the synthetic pathway free from any functional group protection/deprotection requirements. This feature also allows for alteration of the modification sequence.

A general synthetic strategy to prepare poly(ethylene glycol)-based multifunctional copolymers

We report polyethylene glycol-based reactive diblock copolymer as well as random copolymer scaffolds that can be transformed into desired bifunctional copolymers in two synthetic steps. Synthesis of the general scaffolds is achieved via a controlled atom transfer radical polymerization process while the functional groups are introduced via thiol–epoxy ‘click’ and esterification reactions.

Synthesis and self-assembly of dynamic covalent block copolymers

A diblock copolymer is designed to have incompatible blocks, unsymmetrical block lengths, and a reversible linkage. This copolymer self-assembles into nanostructured cylindrical morphology in thin films. Removal of the nanosized cylinders by breaking the reversible linkage then affords nanoporous membranes featuring a chemically reactive functionality in the pores.

Effect of precursor chemical composition on the formation and stability of G-quadruplex core supramolecular star polymers

A homologous series of guanosine end-functional poly(butadiene)s has been prepared. The potassium cation-templated assembly of these guanosine functionalised precursors then furnished supramolecular star polymers with a G-quadruplex core. Comparison with the previously reported poly(ethylene glycol)-based supramolecular star polymers revealed that in designing supramolecular star polymers, chemically non-polar assembly precursors – that do not interfere with the supramolecular interactions of the core – are essential for the preparation of high stability and high molecular weight supramolecular branched architectures. In addition, in comparison to star polymers composed of chemically polar polymer chains, the non-polar supramolecular ensembles show chain-length independent properties.

Introducing a reversible linkage to block copolymer self-assembly: towards controlling nanopore chemistry.

Block copolymer self-assembly[1] has shown remarkable potential towards preparation of highly ordered nanoporous membranes.[2] In this approach, covalently connected yet chemically dissimilar polymer blocks phase separate into ordered nanostructures with length scales on the order of ten to a hundred nanometres. Selective removal of the minor phase from these nanostructured polymer thin films affords nanoporous membranes. Such membranes have found use in surface patterning, templated nanomaterial synthesis, separation, filtration, catalysis, sensing, and drug delivery applications. The far-ranging applicability and performance of these porous materials will further enhance if the surface of the nanopore can carry chemically reactive functionalities that can be altered under ambient conditions. So far, strategies for covalent chemical functionalization of the nanopores in highly ordered porous thin films remains undeveloped. To this end, we designed and synthesized a diblock copolymer featuring incompatible blocks, unsymmetrical block lengths, and a reversible copolymer linkage (Fig. 1 and Scheme 1).[3] Self-assembly of this copolymer results in nanostructured thin films exhibiting highly ordered cylindrical morphology (Fig. 2). Removal of the nanosized cylinders by reversing the dynamic covalent – oxy-imine – linkage then affords ordered nanoporous membranes that contain chemically reactive oxy-amine functionalities. Covalent and non-covalent membrane-functionalization were carried out both by reestablishing imine bonds with fluorescent organic molecules and via forming metal complexes. Received: May 7, 2012