Satyasankar Jana

Transparent, flexible and highly conductive ion gels from ionic liquid compatible cyclic carbonate network

Transparent, flexible, self-standing and highly ion conductive ion gels have been synthesised from novel ionic liquid compatible cyclic carbonate (CC) network polymer. The use of dual functional cyclic carbonate methacrylate (CCMA) monomer for the synthesis has enabled versatile and operationally simple routes to such type of ion gels.

Sulfobetaine-based polymer brushes in marine environment: Is there an effect of the polymerizable group on the antifouling performance?

Three different zwitterionic polymer brush coatings for marine biofouling control were prepared by surface-initiated atom transfer radical polymerization (ATRP) of sulfobetaine-based monomers including methacrylamide (SBMAm), vinylbenzene (SBVB) and vinylimidazolium (SBVI). None of these brush systems have been assessed regarding marine antifouling performance. Antifouling tests performed indicate that surfaces featuring these three brush systems substantially reduce the adhesion of the marine microalgae, Amphora coffeaeformis, and the settlement of cyprid larvae of the barnacle, Amphibalanus amphitrite, in a similar way, displaying comparable performance. Thus, it appears that the chemical structure of the polymerizable group has no substantial influence on marine antifouling performance.

Dual hydrophilic and salt responsive schizophrenic block copolymers – synthesis and study of self-assembly

A new class of dual hydrophilic diblock copolymers (BCPs) possessing poly(ethylene glycol) (PEG) and zwitterionic polysulfabetaine (PSB) was synthesized by reversible addition–fragmentation chain transfer (RAFT) polymerization. These BCPs formed schizophrenic micelles undergoing core–shell transitions upon changing the medium from deionized water to an electrolyte solution. “Conventional” micelles, i.e. PSB at the core and PEG at the periphery, were formed in deionized water. The micelles “inverted” to form PSB at the shell and PEG at the core in electrolyte solutions. The reversal of core–shell structures was thoroughly studied by 1H-NMR spectroscopic analysis, dynamic light scattering (DLS) and transmission electron microscopic (TEM) techniques. Antifouling evaluation in the sea indicated that BCPs displayed antifouling behaviour to some extent. The dual hydrophilic BCPs reported here are potentially useful as stimuli responsive materials.

Halophilic polysulfabetaines – synthesis and study of gelation and thermoresponsive behavior

Polysulfabetaines (PSBs) derived from zwitterionic sulfates (contrary to commonly used polysulfobetaines which are derived from zwitterionic sulfonates) were synthesized for the first time. PSBs dissolved in brine (halophilic), swelled in deionized water and also exhibited reversible and irreversible thermoresponsive behavior. Large differences in interaction with deionized water and brine solution as well as morphology of particles in dispersion was observed between poly[2-(dimethyl(4-vinylbenzyl)ammonio)ethyl sulfate] (PSB 1) and poly[3-(dimethyl(4-vinylbenzyl)ammonio)propyl sulfate] (PSB 2) even though a single methylene (–CH2–) unit was the sole differentiating factor. The gelation and thermoresponsive behaviour observed in PSBs are similar to that of naturally occurring polymers.

Unimolecular ligand–initiator dual functional systems (ULIS) for low copper ATRP of vinyl monomers including acrylic/methacrylic acids

A novel approach for ATRP has been developed which enables the polymerization of vinyl monomers including those bearing carboxylic acid groups such as acrylic/methacrylic acid in the free acid form with ppm amounts of copper. The quantity of copper used in the polymerization is comparable to those left in purified polymers obtained by a conventional ATRP process.

Nucleophile-initiated anionic polymerization of zwitterionic monomers derived from vinylpyridines in aqueous media under ambient aerobic conditions

Polymerizations in aqueous medium under ambient and aerobic conditions mimic natural processes. Hereby we report an anionic polymerization of vinylpyridine (VP) based zwitterionic monomers by organic and inorganic nucleophiles in water, in the presence of air and at room temperature. The polymerization was initiated by a nucleophile, propagated via a carbanionic mechanism, showing living characteristics. This is a unique example of anionic solution polymerization of a vinyl monomer progressing in aqueous media. Zwitterionic polymers of different chain end functionalities including radically polymerizable vinyl groups were synthesized by utilizing different nucleophiles as the initiator. Furthermore, the electron charge distribution of the monomer and propagating species and the polymerization energies of different polymerization steps were calculated using density functional theory (DFT) calculations and the active–dormant resonance hybrid structure of the propagating carbanion was validated with DFT. This investigation opens up a new, facile way of synthesizing functional zwitterionic polymeric materials, novel functionalization possibilities of surfaces containing nucleophile groups and a novel way of synthesizing macromonomers.