Thermo-responsive glycopolymer chains grafted onto honeycomb structured porous films via RAFT polymerization as a thermo-dependent switcher for lectin Concanavalin a conjugation

Self-Assembly of CsPbBr3 Perovskites in Micropatterned Polymeric Surfaces: Toward Luminescent Materials with Self-Cleaning Properties

In this work, we present a series of porous, honeycomb-patterned polymer films containing CsPbBr₃ perovskite nanocrystals as light emitters prepared by the breath figure approach. Microscopy analysis of the topography and composition of the material evidence that the CsPbBr₃ nanocrystals are homogeneously distributed within the polymer matrix but preferably confined inside the pores due to the fabrication process. The optical properties of the CsPbBr₃ nanocrystals remain unaltered after the film formation, proving that they are stable inside the polystyrene matrix, which protects them from degradation by environmental factors. Moreover, these surfaces present highly hydrophobic behavior due to their high porosity and defined micropatterning, which is in agreement with the Cassie-Baxter model. This is evidenced by performing a proof-of-concept coating on top of 3D-printed LED lenses, conferring the material with self-cleaning properties, while the CsPbBr₃ nanocrystals embedded inside the polymeric matrix maintain their luminescent behavior.

CO2-Triggered ON/OFF Wettability Switching on Bioinspired Polylactic Acid Porous Films for Controllable Bioadhesion

Bioinspired honeycomb-like porous films with switchable properties have drawn much attention recently owing to their potential application in scenarios in which the conversion between two opposite properties is required. Herein, the CO₂-gas-triggered ON/OFF switching wettability of biocompatible polylactic acid (PLA) honeycomb porous films is fabricated. Highly ordered porous films with diameters between 2.0 and 2.8 μm are separately prepared from complexes of nonresponsive PLA and a CO₂-sensitive melamine derivative [N²,N⁴,N⁶-tris(3-(dimethylamino)propyl)-1,3,5-triazine-2,4,6-triamine, MET] via the breath figure method. The hydrophilic CO₂-sensitive groups can be precisely arranged in the pore's inner surface and/or top surface of the films by simply changing the PLA/MET ratio. The sensitive groups in the pore's inner surface act as a switch triggered by CO₂ gas controlling water to enter the pores or not, thus resulting in ON/OFF switching wettability. The largest response of the water contact angle of honeycomb films reaches 35°, from 100 to 65°, leading to an obvious hydrophobic-hydrophilic conversion. The improved surface wettability enhances the interaction between the cell and honeycomb film surface, thus resulting in a better cell attachment. Such smart properties accompanying the biocompatible polymer and biological gas trigger facilitate possible biomedical and bioengineering applications in the future for these films.

Bio-Inspired Silica Films Combining Block Copolymers Self-Assembly and Soft Chemistry: Paving the Way toward Artificial Exosqueleton of Seawater Diatoms

This review is in line with the principles of bio-inspiration and biomimicry in order to envisage a softer and more environmentally friendly chemistry. Here, the source of inspiration is a microalga from the oceans with the ability to build an exoskeleton of silica under ambient conditions. Following this model, this review is interested in different ways of creating porous silica films with a hierarchical porosity similar to diatoms. For this purpose, polymeric/hybrid/inorganic films structured in honeycomb using the breath figure method are reported. This versatile and easy to implement method based on the principle of rapid evaporation of a solvent in a humid atmosphere is widely used in the formation of structured films with micron-sized pores. In addition to this, the self-assembly of copolymer at the nanoscale can be addressed to obtain a hierarchically structured film. Following this structuration step, the degradation of a sacrificial block is then described from the most energy-intensive to soft process, allowing an added nanoporosity to the micron porosity of the BF method. Finally, hierarchical porous silica films are described using the sol-gel process, which is known as a soft chemistry process.

Direct formation of hydrophilic honeycomb film by self-assembly in breath figure templating of hydrophobic polylacticacid/ionic surfactant complexes

Honeycomb-patterned porous films with good surface wettability have great potential applications in various areas. However, hydrophilic honeycomb films are difficult to obtain using the direct self-assembly of pure (co)polymers. Thus, additional and special treatments are required to improve film wettability, which makes the procedure complicated and difficult to access. In this study, a facile way to prepare hydrophilic honeycomb-structured porous films is proposed that uses the direct self-assembly of complexes of biocompatible hydrophobic poly(l-lactic acid) and dodecyltrimethylammonium chloride by breath figure templating. The addition of ionic surfactant not only improves film quality but also confers good wettability. The obtained hydrophilic pore arrays were found to effectively promote cell attachment. Such a hydrophilic honeycomb-patterned porous film could find potential applications where pore wetting is required, including tissue engineering, lithography, and nanoparticle embedding.

CO2-Driven reversible wettability in a reactive hierarchically patterned bio-inspired honeycomb film

A triple structured honeycomb film is fabricated through block copolymer directed self-assembly in “Breath Figure” templating as a clickable patterned platform to enhance its reversible surface wettability between hydrophobicity and hydrophilicity upon a biological CO₂ trigger.

Controlling pre-osteoblastic cell adhesion and spreading on glycopolymer brushes of variable film thickness

Controlling the cell behavior on biocompatible polymer surfaces is critical for the development of suitable medical implant coatings as well as in anti-adhesive applications. Synthetic glycopolymer brushes, based on sugar methacrylate monomers have been reported as robust surfaces to resist protein adsorption and cell adhesion. In this study, poly(D-gluconamidoethyl methacrylate) (PGAMA) brushes of various chain lengths were synthesized directly from initiator functionalized glass substrates using surface-initiated atom transfer radical polymerization. The glycopolymer film thicknesses were determined by ellipsometry, whereas the wettability and the morphology of the surfaces were characterized by static water contact angle measurements and atomic force microscopy, respectively. Stable, grafted films with thicknesses in the dry state between 4 and 20 nm and of low roughness (~1 nm) were obtained by varying the polymerization time. Cell experiments with MC3T3-E1 pre-osteoblasts cultured on the PGAMA brushes were performed to examine the effect of film thickness on the cell morphology, cytoskeleton organization and growth. The results revealed good cell spreading and proliferation on PGAMA layers of low film thickness, whereas cell adhesion was prevented on polymer films with thickness higher than ~10 nm, indicating their potential use in medical implants and anti-adhesive surfaces, respectively.

Fructose-Based Acrylic Copolymers by Emulsion Polymerization

The exploration of a renewable resource for the preparation of waterborne copolymers was conducted. Low molar mass sugar resources were selected for their wide availability. A fructose-based monomer (MF) bearing a methacrylate radically polymerizable group was successfully synthesized. The latter was shown to be able to homopolymerize in emulsion. The high Tg of the resulting polymer (about 115 °C) makes it of particular interest for adhesive and coating applications where hard materials are necessary to ensure valuable properties. As a result, its incorporation in waterborne acrylic containing formulations as an equivalent to petrochemical-based methyl methacrylate was investigated. It was found that the bio-based monomer exhibited similar behavior to that of common methacrylates, as shown by polymerization kinetics and particle size evolution. Furthermore, the homogeneous incorporation of the sugar units into the acrylate chains was confirmed by a unique glass transition temperature in differential scanning calorimeter (DSC). The potential of MF for the production of waterborne copolymers was greatly valued by the successful increase of formulation solids content up to 45 wt %. Interestingly, polymer insolubility in tetrahydrofurane increased with time due to further reactions occurring in storage. Most likely, the partial deprotection of sugar units was the reason for the creation of hydrogen bonding and, thus, physically insoluble entangled chains. This behavior highlights opportunities to make use of hydroxyl groups either for further functionalization or, eventually, for achieving enhanced adhesion on casted substrates.

Designing 3D Biological Surfaces via the Breath-Figure Method

The fabrication of biointerfaces that mimic cellular physiological environments is critical to understanding cell behaviors in vitro and for the design of tissue engineering. Breath figure is a self-assemble method that uses water droplets condensed from moisture as template and ends up with a highly ordered hexagonal pore array; this approach is used to fabricate various biological substrates. This progress report provides an overview of strategies to achieve topographical modifications and chemical-patterned arrays, such as modulation of the pore size, shape and selective decoration of the honeycomb holes. Using recent results in the biological fields, potential future applications and developments of honeycomb structures are commented upon.

Surface-Initiated Controlled Radical Polymerization: State-of-the-Art, Opportunities, and Challenges in Surface and Interface Engineering with Polymer Brushes

The generation of polymer brushes by surface-initiated controlled radical polymerization (SI-CRP) techniques has become a powerful approach to tailor the chemical and physical properties of interfaces and has given rise to great advances in surface and interface engineering. Polymer brushes are defined as thin polymer films in which the individual polymer chains are tethered by one chain end to a solid interface. Significant advances have been made over the past years in the field of polymer brushes. This includes novel developments in SI-CRP, as well as the emergence of novel applications such as catalysis, electronics, nanomaterial synthesis and biosensing. Additionally, polymer brushes prepared via SI-CRP have been utilized to modify the surface of novel substrates such as natural fibers, polymer nanofibers, mesoporous materials, graphene, viruses and protein nanoparticles. The last years have also seen exciting advances in the chemical and physical characterization of polymer brushes, as well as an ever increasing set of computational and simulation tools that allow understanding and predictions of these surface-grafted polymer architectures. The aim of this contribution is to provide a comprehensive review that critically assesses recent advances in the field and highlights the opportunities and challenges for future work.

Thermoresponsive copolymers with pendant d-galactosyl 1,2,3-triazole groups: synthesis, characterization and thermal behavior

A series of glycopolymers containing d-galactosyl 1,2,3-triazole groups were synthesized which exhibited thermosensitivity properties.

Glycopolymer code based on well-defined glycopolymers or glyconanomaterials and their biomolecular recognition

Advances in the glycopolymer technology have allowed the preparation of more complex and well-defined glycopolymers/particles with several architectures from linear to globular structures (such as micelles, dendrimers, and nanogels). In the last decade, functionalized self-assembled/decided nano-objects and scaffolds containing glycopolymers were designed to develop many biological and biomedical applications in diseases treatments such as pathogen detection, inhibitors of toxins, and lectin-based biosensors. These studies will facilitate the understanding and investigation of the sugar code on the carbohydrate-lectin interactions, which are significantly influenced by the glycopolymer architecture, valency, size, and density of binding elements. In this context, these advanced and selected glycopolymers/particles showing specific interactions with various lectins are highlighted.

Thermoresponsive copolymer decorated surface enables controlling the adsorption of a target protein in plasma

The control of protein/surface interactions by external stimuli is often required in bioapplications such as bioseparation and biosensors. Although regulation of protein adsorption has been achieved on the surfaces modified with stimuli-responsive polymers, controlled protein adsorption is still challenging for a target protein in a multiprotein system. The present study developed a concept of surface design for the controlled adsorption of a specific protein from plasma by combining a thermoresponsive polymer with an affinity ligand on the surface. In this regard, a polyurethane (PU) surface was modified with the copolymer of N-isopropylacrylamide (NIPAAm) and a ε-lysine-containing monomer (LysMA). ε-Lysine is a specific ligand for plasminogen that was used as the model "target protein" in this study. The PU-P(NIPAAm-co-Lys) surfaces exhibited distinct thermoresponsivity of plasminogen adsorption from plasma with a larger quantity adsorbed at 37 °C than at 23 °C. By contrast, the surfaces showed a low level of adsorption for other plasma proteins at both temperatures. In addition, plasminogen adsorbed on a PU-P(NIPAAm-co-Lys) surface could be partly desorbed by lowering the temperature, and the activity of plasminogen adsorbed was well preserved. We believe that the concept developed in this study can be extended to other proteins by combining PNIPAAm and specific ligands with affinities for the proteins of interest.

Multiple interfaces in self-assembled breath figures

Progress in the breath figure method is reviewed by emphasizing the role of the multiple interfaces and the applications of honeycomb films in separation, biocatalysis, biosensing, templating, stimuli-responsive surfaces and adhesive surfaces.

Fabrication of structured porous films by breath figures and phase separation processes: tuning the chemistry and morphology inside the pores using click chemistry

Herein, a facile water-assisted templating technique, the so-called breath figures method, in combination with phase separation process, was employed to prepare multifunctional micropatterned films. Tetrahydrofuran solutions of incompatible ternary blends consisting of high-molecular-weight polystyrene, an amphiphilic block copolymer, polystyrene-b-poly[poly(ethylene glycol) methyl ether methacrylate] (PS40-b-P(PEGMA300)48), and a fluorinated homopolymer, poly(2,3,4,5,6-pentafluorostyrene) (P5FS21) were casted under humid atmosphere varying the proportion of the components. Two simultaneously occurring processes, i.e., the breath figures mechanism and the phase separation process, lead to unprecedented morphologies that could be tuned by simply varying the relative humidity or the composition of the blend. Confocal micro-Raman spectroscopy served to provide information about the location and distribution of the different functionalities in the films. As a result, both the amphiphilic block copolymer and the fluorinated polymer were mainly located in the cavities. Above a certain percentage of relative humidity, honeycomb structured films were obtained in which the block copolymer is distributed on the edge of the pore as a result of the affinity by the condensing water droplet and the coffee stain effect. The homopolymer is also preferentially situated at the pore edge, but forming spherical domains with narrow polydisperse sizes. Moreover, thiolated glucose molecules were specifically attached to the P5FS21 domains via thiol-para fluorine "click" reaction. Subsequently, the specific lectin (Concanavalin A, Canavalia ensiformis) was attached to the surface by conjugation with the glucose moieties. The successful binding of the Con A was demonstrated by the fluorescence, observed exclusively at the areas where P5FS21 domains are located. This nonlithographic method opens a new route to fabricate a huge variety of microstructured polymer films in terms of morphology not only for protein patterning, as illustrated in this manuscript, but also to produce a diversity of functional group arrangements.

Biodegradable, multi-layered coatings for controlled release of small molecules

Incorporation of orthogonal functional groups into biodegradable polymers permits the fabrication of multi-layered thin films with improved adhesion and tunable degradation profiles. The bi-layer structure also allows for accurate control over small molecule release.

Guanidine-Containing Methacrylamide (Co)polymers via aRAFT: Toward a Cell Penetrating Peptide Mimic()

We report the synthesis and controlled radical homo- and block copolymerization of 3-guanidinopropyl methacrylamide (GPMA) utilizing aqueous reversible addition-fragmentation chain transfer (aRAFT) polymerization. The resulting homopolymer and block copolymer with N-(2-hydroxypropyl) methacrylamide (HPMA) were prepared to mimic the behavior of cell penetrating peptides (CPPs) and poly(arginine) (> 6 units) which have been shown to cross cell membranes. The homopolymerization mediated by 4-cyano-4-(ethylsulfanylthiocarbonylsulfanyl)pentanoic acid (CEP) in aqueous buffer exhibited pseudo-first-order kinetics and linear growth of molecular weight with conversion. Retention of the "living" thiocarbonylthio ω-end-group was demonstrated through successful chain extension of the GPMA macroCTA yielding GPMA(37)-b-GPMA(61) (M(w)/M(n) =1.05). Block copolymers of GPMA with the non-immunogenic, biocompatible HPMA were synthesized yielding HPMA(271)-b-GPMA(13) (M(w)/M(n) = 1.15). Notably, intracellular uptake was confirmed by fluorescence microscopy, confocal laser scanning microscopy, and flow cytometry experiments after 2.5 h incubation with KB cells at 4 °C and at 37 °C utilizing FITC-labeled, GPMA-containing copolymers. The observed facility of cellular uptake and the structural control afforded by aRAFT polymerization suggest significant potential for these synthetic (co)polymers as drug delivery vehicles in targeted therapies.

Living Radical Polymerization by the RAFT Process – A Third Update

This paper provides a third update to the review of reversible deactivation radical polymerization (RDRP) achieved with thiocarbonylthio compounds (ZC(=S)SR) by a mechanism of reversible addition-fragmentation chain transfer (RAFT) that was published in June 2005 (Aust. J. Chem. 2005, 58, 379). The first update was published in November 2006 (Aust. J. Chem. 2006, 59, 669) and the second in December 2009 (Aust. J. Chem. 2009, 62, 1402). This review cites over 700 publications that appeared during the period mid 2009 to early 2012 covering various aspects of RAFT polymerization which include reagent synthesis and properties, kinetics and mechanism of polymerization, novel polymer syntheses, and a diverse range of applications. This period has witnessed further significant developments, particularly in the areas of novel RAFT agents, techniques for end-group transformation, the production of micro/nanoparticles and modified surfaces, and biopolymer conjugates both for therapeutic and diagnostic applications.

Bioinspired material based on femtosecond laser machining of cast sheet micromolding as a pattern transfer process

We present herein a simple, fast, and easy-to-use process to replicate poly(methyl methacrylate) (PMMA) plates generating surface effects. First, a femtosecond laser has been used to fabricate, with sufficient accuracy, a periodic pattern on a glass plate at the microscale. This glass plate, used as a master, can be structured on a large distance with a good control of its roughness. Then, the polymer plates were obtained by bulk polymerization without any solvents with a good replication from the cast sheet process, which has been industrially performed for years. Thus, the modification of this process, environmentally friendly, lets us foresee new applications for commodity polymers by introducing visual iridescent properties and hydrophobicity exaltation.