Polymaleimide-Based Polysulfobetaines Bearing Functional and Nonfunctional Hydrophobic Units and Its Aggregation Behavior in Aqueous Media.

Copolymaleimide-based zwitterionic polysulfobetaines (PM-SBs) were prepared by a "top down" method for the first time. Interfacial studies of these polymers showed many interesting characteristics. These PM-SBs did not require any salt in the form of sodium chloride (NaCl) to dissolve in water and exhibited exceptional salt tolerance. PM-SBs showed very mild thermogelling behavior. The viscosity of 5 wt % aqueous solution of polymers increased with increasing concentration of salt without showing any limits within the salt concentrations studied [200g/L of NaCl (3.4 M)] in contrast to other reported zwitterionic polysulfobetaines. Dynamic light scattering (DLS) studies also indicated a structure-dependent particle size with varying concentrations of NaCl solution. The uniformity of particles of 5 wt % aqueous solution of PM-SBs increased with increasing concentration of NaCl. At 0.1 wt % concentration, even in the absence of NaCl, mild aggregation was noticed. The concentration of aggregated particles increased with the increasing concentration of NaCl. Because of the exceptionally high salt tolerance, these polymers are potentially suitable for applications in antifouling, oil field, personal care formulations, and water purification.

Reversible Photo- and Thermoresponsive, Self-Assembling Azobenzene Containing Zwitterionic Polymers.

Commercially available azo dyes bearing amino groups were grafted to zwitterionic copolymers composed of cyclic anhydride functionality. The zwitterionic copolymers were prepared for the first time by polymerizing sulfobetaine (SB) monomer with maleic anhydride (MA) under conventional free radical polymerization as well as reversible addition-fragmentation chain transfer (RAFT) polymerization. Poly(SB- co-MA) self-assembled in deionized water. Azobenzene grafted zwitterionic poly((SB- co-MA)- g-Azo) exhibited multiresponsive behavior. As confirmed by UV-vis spectroscopy, trans → cis isomerization of the azo group was responsible for the photo- and thermal responsive behavior. The photoisomerization was reversible, and no photoaging was detected during the repeated exposure to UV and visible light. The water-soluble nature of photoresponsive azo dye grafted copolymers makes it suitable for applications in biological systems.

Highly monodisperse zwitterion functionalized non-spherical polymer particles with tunable iridescence.

A facile and simple synthetic route towards functionalized non-spherical polymer particles (NSP) with tunable morphologies and iridescence is presented. Monodisperse particles with unique zwitterionic functionality were synthesized via emulsifier-free emulsion polymerization in a single step process. The sulfobetaine comonomer was utilized to induce phase separation in the course of polymerization to achieve anisotropic NSP with controlled morphologies such as quasi-spherical with protruding structures like bulge, eye-ball, and snowman-like nanostructures. Both SEM and TEM analyses revealed anisotropic particles, and phase-separated protrusion morphology with a small increase in aspect ratio. By taking advantage of the monodisperse, colloidally stable NSPs, template free photonic crystal arrays were fabricated through a bottom-up approach. The particles readily self-assemble and exhibit a photonic bandgap with vivid structural colors that arise from ordered structures of different morphologies. Additionally, the salt-responsive photonic crystals also possess tunable color-changing characteristics.

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.

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.

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.

Water swelling, brine soluble imidazole based zwitterionic polymers--synthesis and study of reversible UCST behaviour and gel-sol transitions.

New vinylbenzene substituted imidazole based zwitterionic polymers with unique characteristics like swelling in water and solubility in concentrated brine solution in which they exhibited a reversible upper critical solution temperature (UCST) and gel-sol transitions are reported herein.

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.

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.

Determination of alkylphenols and bisphenol-A. A comparative investigation of functional polymer-coated membrane microextraction and solid-phase microextraction techniques.

A functional polymer (hydroxylated polymethacrylate) coated on porous polysulfone hollow fiber membrane (PS-HFM) was used as an adsorbent for the extraction of alkylphenols and bisphenol-A from seawater samples. Analyses of the extracts were performed using gas chromatography-mass spectrometry (GC-MS) after injection-port derivatization using bis(trimethylsilyl)trifluoroacetamide (BSTFA). We term the procedure as polymer-coated hollow fiber microextraction (PC-HFME). Owing to high porosity PS-HFM coated with hydroxylated polymer showed high extraction efficiency. Compared with solid-phase microextraction (SPME), PC-HFME showed good selectivity and sensitivity. Detection limits of alkylphenols and bisphenol-A ranged between 0.07 and 2.34 ng l(-1). The linearity range was from 0.01 to 15 microg l(-1) and the correlation coefficient (r) up to 0.997. The sensitivity and selectivity of the coated HFM could be potentially tuned by changing the characteristics of the coated hydroxylated polymer. The PC-HFME procedure was applied to the detection of alkylphenols and bisphenol-A in the coastal waters of Singapore.