Gold-decorated block copolymer microspheres (BCP-microspheres) displaying various surface morphologies were prepared by the infiltration of Au precursors into polystyrene-b-poly(4-vinylpyridine) (PS-b-P4VP) microspheres. The microspheres were fabricated by emulsifying the PS-b-P4VP polymers in chloroform into a surfactant solution in water, followed by the evaporation of chloroform. The selective swelling of the P4VP domains in the microspheres by the Au precursor under acidic conditions resulted in the formation of Au-decorated BCP-microspheres with various surface nanostructures. As evidenced by transmission electron microscopy (TEM) and scanning electron microscopy (SEM) measurements, dotted surface patterns were formed when microspheres smaller than 800 nm were synthesized, whereas fingerprint-like surface patterns were observed with microspheres larger than 800 nm. Au nanoparticles (NPs) were located inside P4VP domains near the surfaces of the prepared microspheres, as confirmed by TEM. The optical ...

Gold-decorated block copolymer microspheres with controlled surface nanostructures.

Abstract A zwitterionic sulfobetaine polymer, poly(N,N-dimethyl(acrylamidopropyl) ammonium propane sulfonate) (poly(DMAAPS)), and the hydrogels of this polymer were synthesized by free-radical polymerization in an aqueous redox system using a wide range of monomer concentrations (Cm). The resulting polymers were characterized in terms of polymer yield, intrinsic viscosity, molecular weight, gel fraction, and thermoresponsive phase-transition behavior. Parameters in the Mark–Houwink–Sakurada equation, including the molecular-weight exponent α, were determined for poly(DMAAPS) in 0.1 M NaCl aqueous solution. The physical state and transparency of the poly(DMAAPS) samples were strongly dependent on Cm and temperature. At higher values of Cm (i.e. above a critical molecular weight), poly(DMAAPS) became a gel comprising a physically crosslinked network consisting of entangled polymer chains and interchain associations of the zwitterionic groups. The poly(DMAAPS) solutions or gels exhibited a thermoresponsive phase transition with an upper critical solution temperature (UCST). The gels obtained were completely soluble in aqueous NaCl solution at ambient temperature as well as in water at temperatures above UCST. The effects of molecular weight, chemical crosslink density and copolymerization on the UCST were also elucidated.

Characteristics of zwitterionic sulfobetaine acrylamide polymer and the hydrogels prepared by free-radical polymerization and effects of physical and chemical crosslinks on the UCST

Molecular self-assembling block copolymers (BCPs) have shown promise as a next generation bottom-up lithography technology. However, a critical step in advancing this approach is the elimination of polymer dewetting due to bulk solvent nucleation and thermodynamically driven film rupture that can occur during the solvent vapor annealing process. We report on the pattern formation via phase segregation of spin coated diblock copolymer films through the investigation of annealing parameters in the limit of high solvent vapor saturation conditions that results in wafer-scale patterning without observing polymer dewetting defects. Specifically, the work addresses polymer dewetting in diblock copolymer nanodot templates through the use of a “neutral” functionalization layer and the development of a custom-built solvent vapor annealing chamber to precisely control saturation conditions. Furthermore, the long anneal times (4 h) using a standard static solvent vapor annealing procedure were reduced to ∼15–30 minutes with our dynamic solvent vapor annealing system for the high χ, cylindrical forming poly(styrene)-block-poly(4-vinyl-pyridine) [PS-b-P4VP] diblock copolymer system. We discuss the kinetic mechanism governing the phase segregation process that highlights the small processing window bounded by long phase segregation timescales (≳1 min) on one side and the initiation of polymer film dewetting on the other. These results demonstrate a key step towards realizing a high fidelity, low cost BCP patterning technique for large-scale “bottom-up” feature definition at nanometer length scales.

Controlled solvent vapor annealing of a high χ block copolymer thin film

A new method for the preparation of new heterocyclic amine surfactants based on sulfobetaines is proposed. Interfacial activities of the surfactants obtained in aqueous solution were studied by surface tension measurements. The critical micelle concentration, surface excess concentration, minimum area per surfactant molecule, and standard Gibbs energy of adsorption were determined. The adsorption properties of these compounds depend significantly on the alkyl chain length. Alkyl chain length also affects biological properties of the new surfactants, determining the minimum inhibitory concentration and size of inhibited growth zone. The compounds have high antimicrobial activity.

https://link.springer.com/content/pdf/10.1007/s11743-016-1906-8.pdf

Synthesis, Surface and Antimicrobial Activity of Piperidine-Based Sulfobetaines

Solvent vapor annealing is as an effective and versatile alternative to thermal annealing to equilibrate and control the assembly of polymer chains in thin films. Here, we present scientific and practical aspects of the solvent vapor annealing method, including the discussion of such factors as non-equilibrium conformational states and chain dynamics in thin films in the presence of solvent. Homopolymer and block copolymer films have been used in model studies to evaluate the robustness and the reproducibility of the solvent vapor processing, as well as to assess polymer-solvent interactions under confinement. Advantages of utilizing a well-controlled solvent vapor environment, including practically interesting regimes of weakly saturated vapor leading to poorly swollen states, are discussed. Special focus is given to dual temperature control over the set-up instrumentation and to the potential of solvo-thermal annealing. The evaluated insights into annealing dynamics derived from the studies on block copolymer films can be applied to improve the processing of thin films of crystalline and conjugated polymers as well as polymer composite in confined geometries.

https://www.mdpi.com/2073-4360/11/8/1312/pdf

Temperature-Controlled Solvent Vapor Annealing of Thin Block Copolymer Films

Investigation of ion adsorption properties of sulfobetaine gel and relationship with its swelling behavior

Effects of specific anions on the relationship between the ion-adsorption properties of sulfobetaine gel and its swelling behavior

The morphology of polystyrene-b-poly(2-vinyl pyridine) thin films annealed under various neutral solvents was investigated. The morphological transition depends on the vapor pressure of the solvent, the quantity of the solvent in the film, and annealing time. We introduced the volume fraction of solvent in a film (Q) to correlate these factors to the morphology. At low Q, the amount of solvent that penetrates into the film is limited and it cannot induce enough chain mobility. Thus, thin film shows short stripes or a worm-like structure. At high Q, the great diffusion of solvent into the film facilitates polymer mobility, leading to an ordered structure. Our results also suggested that the dewetting mechanism of thin film depends on Q. At low Q, dewetting develops via the nucleation and growth. At high Q, the condensation of solvent on the surface removes some polymer and dewetting is dominated by spinodal mechanism. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers

The nanostructure and dewetting of block copolymer thin films annealed in different neutral solvents

Gel adsorbent produced through the copolymerization reaction between the N-isopropylacrylamide (NIPAM), and N,N-dimethyl(acrylamidopropyl)ammonium propane sulfonate (DMAAPS) has the capability to absorb and desorb ion simultaneously by temperature swing In this study, NIPAM was used as thermosensitive agent and DMAAPS was used as adesorption agent The effects of monomer concentration on the swelling, adsorption, and desorption properties of ions of thermosensitive NIPAM-co-DMAAPS gel were investigated at various temperatures and solution concentrations NaNO3 solution was selected as the target solution and used in swelling, adsorption, and desorption test The results showed that the swelling degree of the copolymer gel increase as temperature, solution, and NIPAM concentrations increase The amount of ions adsorbed onto the copolymer gel increased with solution concentration However, it decreased with increasing temperature and NIPAM concentration in the gel It also was found that the amount of ion 

Ion adsorption and desorption behaviors of thermosensitive NIPAM-co-DMAAPS gel by temperature swing

The development of structure of symmetric polystyrene-b-poly(2 vinyl pyridine) (PS-PVP) thin film annealed under a neutral solvent vapor was investigated by atomic force microscopy and optical microscopy. Initially, spin cast film showed a micellar structure. With subsequent neutral solvent vapor treatment, a lamellar structure gradually developed. It was found that the structural evolution of the thin film was a strong function of the quantity of solvent diffused into the film. In addition, with an increase in swelling, the orientation of the lamellae changed from parallel to perpendicular. During solvent annealing, the solvent also induced dewetting via primary and secondary heterogeneous nucleation processes, depending on the quantity of solvent in the film. Secondary nucleation was independent of primary nucleation for lower solvent concentration. With higher amount of solvent, the solvent expedited secondary nucleation, and it occurred within the dewetted area caused by primary nucleation.

Eva Oktavia Ningrum

Papers

Investigation of ion adsorption properties of sulfobetaine gel and relationship with its swelling behavior

Effects of specific anions on the relationship between the ion-adsorption properties of sulfobetaine gel and its swelling behavior

The nanostructure and dewetting of block copolymer thin films annealed in different neutral solvents

Ion adsorption and desorption behaviors of thermosensitive NIPAM-co-DMAAPS gel by temperature swing

Effect of Solvent Annealing on the Nano- and Micro-Structure of Block Copolymer Thin Film