Anbanandam Parthiban

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.

Salt-Responsive Polysulfabetaines from Acrylate and Acrylamide Precursors: Robust Stabilization of Metal Nanoparticles in Hyposalinity and Hypersalinity.

Metal nanoparticles (MNps) tend to be influenced by environmental factors such as pH, ionic strength, and temperature, thereby leading to aggregation. Forming stable aqueous dispersions could be one way of addressing the environmental toxicity of MNps. In contrast to the electrolyte-induced aggregation of MNps, novel zwitterionic sulfabetaine polymers reported here act as stabilizers of MNps even under high salinity. Polysulfabetaines exhibited unique solubility and swelling tendencies in brine and deionized water, respectively. The polysulfabetaines derived from methacrylate (PSBMA) and methacrylamide (PSBMAm) also showed reversible salt-responsive and thermoresponsive behaviors as confirmed by cloud-point titration, transmittance, and dynamic light scattering studies. The brine soluble nature was explored for its ability to be used as a capping agents to form metal nanoparticles using formic acid as a reducing agent. Thus, silver and noble metal (gold and palladium) nanoparticles were synthesized. The nanoparticles formed were characterized by UV-vis, XRD, TEM, EDX, and DLS studies. The size of the nanoparticles remained more or less the same even after 2 months of storage in 2 M sodium chloride solution under ambient conditions and also at elevated temperatures as confirmed by light-scattering measurements. The tunable, stimuli-responsive polysulfabetaine-capped stable MNp formed under low (hyposalinity) and hypersalinity could find potential applications in a variety of areas.

Triblock copolymers composed of soft and semi-crystalline segments—synthesis and characterization of poly[(n-butyl acrylate)-block-(ε-caprolactone)-block-(L-lactide)]

Poly(n-butyl acrylate) terminated with benzyl alcohol units (PnBA-MI) of varying molecular weights were synthesized by polymerizing n-butyl acrylate using substituted benzyl alcohol based initiators under atom transfer radical polymerization (ATRP) conditions. Between the ligands bipyridine and PMDETA, the latter ligand showed better control for the polymerization of n-BA. High molecular weight diblock copolymers of poly[(n-butyl acrylate)-block-(e-caprolactone)] were synthesized by ring opening polymerization (ROP) of e-caprolactone using PnBA-MI which formed thin, flexible and opaque films which are soft to touch. Triblock copolymers of poly[(n-butyl acrylate)-block-(e-caprolactone)-block-(L-lactide)] were synthesized in a one pot, two step reaction by the sequential addition of monomers. The molecular weights of PCL and PL segments in the triblock copolymers were comparable. Due to this, the triblock copolymer showed exothermic transition upon cooling well above the Tm of PCL block.

Antibacterial, electrospun nanofibers of novel poly(sulfobetaine) and poly(sulfabetaine)s

Polymers capable of forming hydration layers have gained increasing attention due to their ability to form environmentally friendly antifouling surfaces. Zwitterionic polymers are an important class of materials under this category. However, the effectiveness of many zwitterionic polymers for long-term applications is compromised because of their solubility in sea water, poor hydrolytic stability and deteriorating mechanical integrity upon wetting. This study reports on the preparation and characterization of electrospun fibers derived from novel polysulfobetaine and polysulfabetaines (PSBs) composed of polyvinylbenzyl backbones. The morphology of the electrospun nanofibers was elucidated with the help of a scanning electron microscope. Hydration studies were conducted in deionized water and artificial sea water. Antifouling performance of the electrospun nanofibers was evaluated by studying the adhesion and growth of bacteria in natural, and filtered sea water. Terminal restriction fragment length polymorphism (TRFLP) fingerprinting was performed to determine the nature of the bacterial community attached to the electrospun fibers. Some of the PSBs prevented bacterial growth without showing any biocidal nature. Thus the findings of this study are potentially relevant for current trends seeking environmentally friendly antifouling solutions.

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.

A new addition to the family of polyesters—Synthesis and characterization of novel (alternating) poly(ether ester)s, poly(butylene 3-/4-hydoxy benzoate)s

AbstractNovel, predominantly alternating poly(ether ester)s, poly(butylene-3/4-hydroxy benzoate)s (PBHB)s were synthesized by the hydrogenation of the corresponding unsaturated polymers obtained by forming ether and ester linkages under one pot conditions. The ether substitution caused a reduction in glass transition temperature, Tg. The melting transition was also lowered by more than 100°C compared to poly(butylene terephthalate) as studied by the differential scanning calorimetry (DSC). Crystallization was observed during heating as well as cooling in the DSC studies. Wide angle X-ray diffraction (WAXRD) analysis also indicated that PB-4-HB was semi-crystalline in nature. The thermal stability of hydrogenated polymer was better than that of the unsaturated polymer. FigureReplacing one of the ester groups by ether in polyesters increases the flexibility of the polymer backbone, thereby inducing crystallization and drastically reducing the melting transition.

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.