Self-assembly of physically crosslinked micelles of poly(2-acrylamido-2-methyl-1-propane sulphonic acid-co-isodecyl methacrylate)-copper(II) complexes

Metal complexes were prepared by the reaction of Cu(II) chloride with sodium salt of random copolymers of 2-acrylamido-2-methylpropane sulphonic acid, AMPS, and isodecyl methacrylate, i-DMA. Composition was varied in the feed to obtain copolymers and their corresponding metal chelates with different content of i-DMA hydrophobic monomer. The copolymers and their metal chelates were characterized by Fourier transformed IR spectroscopy (FTIR) and scanning electron microscopy (SEM) as well as energy-dispersive X-ray spectroscopy (EDS). The X-ray diffraction studies revealed that the polymers and their chelates were amorphous. Also, the stabilities of the copolymers and their metal chelates were investigated using thermal methods such as TGA and DSC analysis. Lower thermal stability was found for the polymer–metal complexes compared to that of the copolymers. Fluorescence spectroscopy was used to further confirm the copolymers and their Cu(II) metal complexes self-aggregate in water. Critical micellar concentrations become lower by metal complexation. A synergistic effect in self-assembly behaviour in water solutions of Cu(II) polycomplexes is attributed to the interplay between hydrophilic–hydrophobic interactions and electrostatic forces with Cu²⁺ ions. Physical crosslinking of polymeric micelles obtained by metal complexation led to more stable micelles. Sodium salt copolymers led to secondary aggregation while ionic crosslinking provided lonely micelles distributed through the substrate as seen by SEM. These results point to a mechanism in which cation-assisted-polymer-modified water structure plays a central role in the phase separation behaviour.The authors would like to thank the Plan Nacional I+D+I (Ministerio de Educación y Ciencia) for financial support (MAT2006-05979) as well as the Comunidad Autónoma de Madrid for the funding through I+D Program (S0505/MAT-0227)

Synthesis and association properties in water solution of random copolymers of 2-acrylamido-2-methyl-1-propane sulfonic acid and isodecyl methacrylate—potential application as surfactants in micellar-enhanced ultrafiltration processes

Hydrophobically modified water-soluble polymers have been prepared by copolymerization of 2-acrylamido-2-methylpropane sulfonic acid (AMPS) and isodecyl methacrylate (iDMA) in N,N-dimethylformamide under nitrogen atmosphere, varying the composition feed. Fluorescence spectroscopy was used to further confirm the copolymers self-aggregate in water. Critical concentration of the self-aggregate formation (CAC) decreased by increasing the molar fraction of iDMA in the AMPSco copolymers and varied between 1.20 and 0.04 g/L depending on the degree of hydrophobic modification. Hence, copolymer composition and charge density allowed tuning the pseudomicellar characteristics of these new amphiphilic copolymers. The addition of a salt or a low-molecular-weight surfactant was studied. Binding of CTAB to the AMPSco copolymers leads to a high decrease of CAC, i.e., 0.006 g/L. Effect of the composition in the viscosimetric behavior of the hydrophobically modified copolymers AMPSco was investigated. The removal of single metal ions, Cu²⁺, and m-cresol from aqueous solutions by ultrafiltration with the help of the copolymers was investigated. Equilibrium dialysis experiments demonstrate that the formation of hydrophobic microdomains can be used to control the sequestration of foulants, and thus these novel copolymers have potential application as polymeric surfactants in micellar-enhanced ultrafiltration processes for water purification

Magneto-mechanical surfaces design

Magneto-mechanically active surfaces (MMAS) represent a new family of nano/micro-structured surfaces in which motion is induced by an external magnetic field. Under the name of artificial cilia, biomimetic cilia, magnetic actuated patterns, nanopillars, etc., published works in this area continue their quick growth in number. Notwithstanding their potential application in microfluidic, chemical sensors, catalytic processes and microelectronics to increase device perfomances, there is still a lot to do in the development of these materials. Improvement and optimization of the performance of these structures are essential tasks in order to fulfil their complete development. Along this article, a critical review involving the main aspects in the design of the patterned nanocomposites will be presented.Authors wish to thank Spanish Ministerio de Economía y Competitividad for finantial support under grant MAT2014-57557-R

Multiphoton Reactive Surfaces Using Ruthenium(II) Photocleavable Cages

Photoreactive surfaces derived from a new photocleavable surface modification agent and with photosensitivity in the Vis and IR region are described. A ruthenium(II) caged aminosilane, [Ru(bpy)₂(PMe₃)(APTS)](PF₆)₂, was synthesized and attached to silica surfaces. Light irradiation removed the cage and generated surface patterns with reactive amine groups. The photosensitivity of this compound under single (460 nm) and two-photon (900) excitation is demonstrated. Functional patterns with site-selective attachment of other molecular species are described.A.d.C., O.F., and R.E. thank the DFG (444ARG113/8/1-0) for financial support. The authors thank Beatriz García (INQUIMAE) for helping with the synthesis part, Andreas Best (MPIP) for the laser scanning experiments, and Juan P. Fernández-Blázquez (MPIP) for help the contrast measurements. R.E. is staff member of CONICET

Synthesis of novel nanoreinforcements for polymer matrices by ATRP: Triblock poly(rotaxan)s based in polyethyleneglycol end-caped with poly(methyl methacrylate)

Poly(rotaxan)s of poly(ethylene glycol) and α-cyclodextrines (CD) block copolymers end-capped with poly(methyl methacrylate) chains were synthesized by atom transfer radical polymerization. The synthesized copolymers were characterized by 1H NMR, 2D NOESY NMR, X-ray and Thermogravimetric analysis. Assuming a maximum relation of 2 CDs per ethyleneglycol unit, a coverage degree of 18% and 15% was achieved. X-ray analysis showed a characteristic signal around 20θ for all copolymers with an amorphous halo mainly due to inter-crystal poly(ethylene glycol) and poly(methyl methacrylate) chains. Full Molecular Dynamics of 20 ns was used to simulate the crystal structure of these copolymers. A pair correlation function was used to determine the coupling between hydrogen atoms of PEG, PMMA and cyclodextrine obtained by 2D NOESY NMRThis work was supported by Comunidad de Madrid (CAM project: S-0505/MAT/0227) and CICYT (project: MAT2007-63722). The authors would like to thank Dr. Berta Herrero

Polyelectrolyte Multilayers Containing Triblock Copolymers of Different Charge Ratio

Multilayers formed by the sodium salt of poly(4-styrenesulfonate), PSS, and triblock copolymers of the form PDMAEMA−PCL−PDMAEMA (PDMAEMA corresponding to poly[2-(N,N-dimethylamino)ethyl methacrylate), and PCL to poly(ε-caprolactone) have been built by layer-by-layer self-assembly from the aqueous polyelectrolyte solutions. Two types of block copolymers have been used which differ on the type of the amino groups, either hydrochloride or quaternized. This leads to changes in the charge density of the chains for the same content of amino groups. The growth of the multilayers has been followed using dissipative quartz crystal microbalance and ellipsometry techniques. The results show that, independently of the conditions used in the assembling, the film thickness grows linearly with the number of layers. The comparison of the thickness values obtained from D-QCM and ellipsometry has allowed us to calculate the water content of the polymer film. The analysis of the D-QCM data also provides the shear modulus, whose values are typical of a rubber-like polymer system. The analysis of the mass adsorbed calculated by the ellipsometric measurements indicated that the nature of the charge compensation mechanism is extrinsic for all the studied systems, although the degree of extrinsic compensation is strongly dependent on the copolymer used and the concentration in solution. Finally, it was found that the adsorption kinetic of the layers is bimodal for all the films built. Even though the characteristic adsorption times depend on the specific copolymer used, no dependence on the number of layers has been found for a given multilayer.This work was supported in part by MICINN under grants FIS2009-14008-C02-01, by CAM under grant INTERFASES S05-MAT-227, and by ESA under grant MAPAO-00-052. E.G. was supported by a FPU fellowship from MICINN. The authors are grateful to the UIRC of the CAI of Spectroscopy of Complutense University for the use of the ellipsometer

Hierarchically organized micellization of thermoresponsive rod-coil copolymers based on poly[oligo(ethylene glycol) methacrylate] and poly(ε-caprolactone)

A series of amphiphilic triblock copolymers, poly[oligo(ethylene glycol) methacrylate]x-block-poly(ε-caprolactone)-block-poly[oligo(ethylene glycol) methacrylate]x, POEGMACo(x), were synthesized. Formation of hydrophobic domains as cores of the micelles was studied by fluorescence spectroscopy. The critical micelle concentrations in aqueous solution were found to be in the range of circa 10⁻⁶ M. A novel methodology by modulated temperature differential scanning calorimetry was developed to determine critical micelle temperature. A significant concentration dependence of cmt was found. Dynamic light scattering measurements showed a bidispersed size distribution. The micelles showed reversible dispersion/aggregation in response to temperature cycles with lower critical solution temperature between 75 and 85 °C. The interplay of the two hydrophobic and one thermoresponsive macromolecular chains offers the chance to more complex morphologies.The authors are indebted to Francesç Catala, from Mettler-Toledo, for valuable discussions. The authors are grateful to LABMET, TEM Laboratory associated to the Comunidad Autónoma de Madrid network and Mr. J. González-Casablanca for his cooperation with the TEM images. The authors would like to thank the Plan Nacional IþDþI (Ministerio de Ciencia e Innovación) for financial support (MAT2009-09671) as well as the Comunidad Autónoma de Madrid for the funding through IþD Program (S0505/MAT-0227)

Bioinspired Underwater Bonding and Debonding on Demand

Mussel glue: Bioinspired underwater chemical bonding with the possibility of phototriggered debonding is reported. A four-arm star-poly(ethyleneglycol) end-functionalized by nitrodopamine was synthesized. The nitrodopamine offered the reactivity of catechol and the chemistry of the photocleavable o-nitrophenyl ethyl group (see picture)