Functionalization Of Polymer Surfaces Research Articles

Investigation of Surface Modification of Polystyrene by a Direct and Remote Atmospheric-Pressure Plasma Jet Treatment.

Localized functionalization of polymer surface with an atmospheric-pressure plasma jet was investigated at various treatment conditions. Polystyrene samples were treated with the plasma jet sustained in argon under direct or remote conditions. The two-dimensional evolution of surface wettability and the spot size of the treated area was determined systematically by measuring apparent water contact angles. Modification of surface chemistry and the formation of functional groups were investigated by X-ray photoelectron spectroscopy (XPS). The saturation of surface wettability and functional groups was observed even after a second of treatment providing the sample was placed close to the exhaust of the discharge tube. The spot diameter of the modified area increased logarithmically with increasing treatment time. However, it decreased linearly when increasing the distance. At the edge of the glowing plasma, however, the modification of surface properties was more gradual, so even 30 s of treatment caused marginal effects. With a further increase in the distance from the edge of the glowing plasma, however, there were no further treatment effects. The results are explained by significant axial as well as radial gradients of reactive species, in particular hydroxyl radicals.

Spatially Engraving Morphological Structure on a Polymeric Surface by Ion Beam Milling.

Polymer surface patterning and modification at the micro/nano scale has been discovered with great impact in applications such as microfluidics and biomedical technologies. We propose a highly efficient fabricating strategy, to achieve a functional polymer surface, which has control over the surface roughness. The key development in this fabrication method is the polymer positive diffusion effect (PDE) for an ion-bombarded polymeric hybrid surface through focused ion beam (FIB) technology. The PDE is theoretically explored by introducing a positive diffusion term into the classic theory. The conductivity-induced PDE constant is discussed as functions of substrates conductivity, ion energy and flux. The theoretical results agree well with the experiential results on the conductivity-induced PDE, and thus yield good control over roughness and patterning milling depth on the fabricated surface. Moreover, we demonstrate a controllable surface wettability in hydrophobic and superhydrophobic surfaces (contact angles (CA) range from 108.3° to 150.8°) with different CA hysteresis values ranging from 31.4° to 8.3°.

Magnetic nanoparticles coated with aminated starch for HSA immobilization- simple and fast polymer surface functionalization

Magnetic nanoparticles coated with polymer shell containing reactive functional groups are of great interest especially as substrates for immobilization of ligands in biomedicine and catalysis. This article describes synthesis of novel functional MNPs coated with aminated starch via simple, fast and efficient method of functionalization of the surface by one-minute pounding in mortar. The concept is based on simplifying the synthesis of the magnetic support and obtaining a material that allows for effective bioligand immobilization. Basing on our previous research in the area of MNPs synthesis and biomedical applications, the high yield (149.96 mg/g of support) and effective immobilization of HSA was demonstrated for these nanoparticles without loss of protein activity. Obtained materials were characterized with ATR-FTIR spectroscopy, scanning (SEM) and transmission (TEM) electron microscopy, dynamic light scattering (DLS), X-ray diffraction, TGA-DTA and SQUID analysis. The developed method allows for modification of polysaccharides and nanoparticles towards materials enriched with amino groups in a quick and easy way. It can be expected that this method of quick solvent-free amination will find application in the chemistry of materials and polymers. In addition, the new obtained amino-rich MNPs may find use as carriers for the immobilization of bioligands in catalysis and pharmaceutical analysis.

Surface functionalization of polyester.

Surface functionalization such as hydrophilization is an important step in the polymer manufacturing process and a key requirement for application of polyesters. Conventional methods like chemical or plasma treatment are often toxic, expensive and adversely affect the mechanical properties of the polymer. Enzymes have proven to be an attractive alternative for surface hydrolysis and functionalization of synthetic polymers since they work under mild and environmental friendly process conditions while preserving the mechanical properties. This chapter deals with the enzymatic surface treatment of polyesters and in particular with current methods for the analysis of polymer hydrolysis and of changes of surface properties.

Demonstration of Polymer Photodegradation Using a Simple Apparatus

Polymer science is widely used in industry, from the development of packaging to the process for obtaining products of all kinds. Despite this omnipresence in the productive sector and our daily lives, topics related to polymer science are not as representative in school curricula. The demonstrations developed in this work address some technological applications of photodegradation, such as the functionalization of nonpolar polymer surfaces to receive water-based paints, and their participation in the deterioration of polymers exposed to the weather. The simplicity and easy-to-make characteristics of the proposed experiments make them eligible to facilitate the discussion of polymer science topics in the classroom.

Improvement of fish protein films properties for food packaging through glow discharge plasma application

Myofibrillar proteins have good film forming ability, that leads to the formation of polymers with interesting properties for food packaging development. However, as other bio-sourced macromolecules, they have limited performance compared to synthetic materials and cold plasma represents a promising strategy to change polymer properties. Alternating current (AC) glow discharge plasma is a novel and innovative approach for surface modification of agro-based films in order to improve their properties. Then, the effects of exposure to AC glow discharge plasma were studied on the physicochemical, microstructural and thermal properties of myofibrillar protein films from fish. Films treated for 2 min showed increased elongation at break and decreased tensile strength, while the opposite behavior was observed after 5 min of treatment. Solubility in water increased with 5 min and water vapor permeability increased with 2 min of plasma treatment. Color and opacity also increased probably as a result of chemical changes because of plasma application. Slight changes were observed in microstructure of the films. Thermal properties results agreed with the modifications observed in physicochemical performance, which might be attributed to polymer surface functionalization and etching. Thus, the AC glow discharge is a promising alternative to other strategies in order to advance properties of myofibrillar protein films for food packaging because it is a dry process, does not cause damage by heating in the material, and does not pollute the environment.

KnowVolution of the Polymer-Binding Peptide LCI for Improved Polypropylene Binding.

The functionalization of polymer surfaces by polymer-binding peptides offers tremendous opportunities for directed immobilization of enzymes, bioactive peptides, and antigens. The application of polymer-binding peptides as adhesion promoters requires reliable and stable binding under process conditions. Molecular modes of interactions between material surfaces, peptides, and solvent are often not understood to an extent that enables (semi-) rational design of polymer-binding peptides, hindering the full exploitation of their potential. Knowledge-gaining directed evolution (KnowVolution) is an efficient protein engineering strategy that facilitates tailoring protein properties to application demands through a combination of directed evolution and computational guided protein design. A single round of KnowVolution was performed to gain molecular insights into liquid chromatography peak I peptide, 47 aa (LCI)-binding to polypropylene (PP) in the presence of the competing surfactant Triton X-100. KnowVolution yielded a total of 8 key positions (D19, S27, Y29, D31, G35, I40, E42, and D45), which govern PP-binding in the presence of Triton X-100. The recombination of two of the identified amino acid substitutions (Y29R and G35R; variant KR-2) yielded a 5.4 ± 0.5-fold stronger PP-binding peptide compared to LCI WT in the presence of Triton X-100 (1 mM). The LCI variant KR-2 shows a maximum binding capacity of 8.8 ± 0.1 pmol/cm2 on PP in the presence of Triton X-100 (up to 1 mM). The KnowVolution approach enables the development of polymer-binding peptides, which efficiently coat and functionalize PP surfaces and withstand surfactant concentrations that are commonly used, such as in household detergents.

Immobilization of Polyoxometalates on Tailored Polymeric Surfaces.

Herein we describe the preparation of hybrid polymer–inorganic interfaces by the immobilization of polyoxometalate nanoclusters on functionalized polymer surfaces. The polymeric surfaces were made of polystyrene-b-poly(acrylic acid)/polystyrene (PS-b-PAA/PS) blends by spin coating on a silicon wafer. The functionalization of the polymer film was obtained by interfacial migration of the amphiphilic block copolymer toward the interface upon water vapor annealing. The carboxylic acid functional groups contained in the PAA block were then employed to anchor the [LnIII(α-SiW11O39)]5− polyoxometalates (Ln: Ce, Er). This purpose was achieved by immersing the films in aqueous solutions of the in situ-formed inorganic nanoclusters. X-ray photoelectron and confocal Raman spectroscopies, together with atomic force microscopy, confirmed the immobilization of the inorganic species at the interface.

Directed evolution of polypropylene and polystyrene binding peptides.

Surface functionalization of biological inert polymers (e.g., polypropylene PP; polystyrene PS) with material binding peptides facilitates an efficient immobilization of enzymes, bioactive peptides or antigens at ambient temperature in water. The developed robust directed evolution protocol enables to tailor polymer binding anchor peptides (PBPs) for efficient binding under application conditions. Key for a successful directed evolution campaign was to develop an epPCR protocol with a very high mutation frequency (60 mutations/kb) to ensure sufficient diversity in PBPs (47 aas LCI: "liquid chromatography peak I"; 44 aas TA2: "Tachystatin A2"). LCI and TA2 were genetically fused to the reporter egfp to quantify peptide binding on PP and PS by fluorescence analysis. The Peptide-Polymer evolution protocol (PePevo protocol) was validated in two directed evolution campaigns for two PBPs and polymers (LCI: PP; TA2: PS). Surfactants were used as selection pressure for improved PBP binders (non-ionic surfactant Triton X-100; 1 mM for LCI-PP // anionic surfactant LAS; 0.5 mM for TA2-PS). PePevo yielded an up to three fold improved PP-binder (LCI-M1-PP: I24T, Y29H, E42 K and LCI-M2-PP: D31V, E42G) and an up to six fold stronger PS-binder (TA2-M1-PS: R3S, L6P, V12 K, S15P, C29R, R30L, F33S, Y44H and TA2-M2-PS: F9C, C24S, G26D, S31G, C41S, Y44Q).

A comparative study of polyethylene terephthalate surface carboxylation techniques: Characterization, in vitro haemocompatibility and endothelialization

Surface functionalization of polymers is crucial for improving biocompatibility and haemocompatibility, which correlates to improved performance of medical devices. Here, we have evaluated the effect of four PET surface carboxylation techniques on the antifouling property, haemocompatibility, and endothelialization. Surface carboxylation was achieved by formaldehyde+bromoacetic acid treatment (PET-1[COOH]), methacrylic acid grafting (PET-2[COOH]), NaOH hydrolysis+KMnO4 oxidation (PET-3[COOH]), and oxygen plasma treatment+acrylic acid grafting (PET-4[COOH]). The carboxyl densities on these surfaces were 0.4, 23.2, 31.9, 16.4nmol/cm2, respectively. XPS and FTIR spectroscopy confirmed the introduction of carboxyl groups. Water contact angle results showed that hydrophilicity increased with an increase in surface carboxyl density. SEM images confirmed that these modifications didn't cause any surface deterioration. AFM studies showed an increase in surface roughness of the carboxylated PET. Tensile testing showed that these modifications did not affect the bulk properties. Compared to control, PET-3[COOH] has a 9-fold reduction in BSA adsorption. Haemocompatibility studies showed significantly reduced %hemolysis and platelet adhesion on the carboxylated PET. Cell culture studies revealed that endothelial cell (EA.hy926) attachment increased with increase in surface carboxyl density. PET-3[COOH] showed the most improved haemocompatibility and endothelial cell attachment. These results clearly show that the method of functionalization has a significant impact on the haemocompatibility and cell attachment.

Variable Lysozyme Transport Dynamics on Oxidatively Functionalized Polystyrene Films.

Tuning protein adsorption dynamics at polymeric interfaces is of great interest to many biomedical and material applications. Functionalization of polymer surfaces is a common method to introduce application-specific surface chemistries to a polymer interface. In this work, single-molecule fluorescence microscopy is utilized to determine the adsorption dynamics of lysozyme, a well-studied antibacterial protein, at the interface of polystyrene oxidized via UV exposure and oxygen plasma and functionalized by ligand grafting to produce varying degrees of surface hydrophilicity, surface roughness, and induced oxygen content. Single-molecule tracking indicates lysozyme loading capacities, and surface mobility at the polymer interface is hindered as a result of all functionalization techniques. Adsorption dynamics of lysozyme depend on the extent and the specificity of the oxygen functionalities introduced to the polystyrene surface. Hindered adsorption and mobility are dominated by hydrophobic effects attributed to water hydration layer formation at the functionalized polystyrene surfaces.

Functionalization of polymer surfaces by medium frequency non-thermal plasma

Abstract This work addresses the surface modification of different polymers by argon dielectric barrier discharge, using bromoform vapours. Atomic Force Microscopy and Scanning Electron Microscopy showed that plasma etching occurs in stages and may be related to the reach of the species generated and obviously the gap between the electrodes. In addition, the stages of flatten surface or homogeneity may be the result of the transient crosslinking promoted by the intense UV radiation generated by the non- thermal plasma. X-ray Photoelectron Spectroscopy analysis showed that bromine was inserted on the polymer surface as C Br bonds and as adsorbed HBr. The obtained results demonstrate that the highest degree of bromofunctionalization was achieved on polypropylene surface, which contains about 8,5% of Br. After its derivatization in ammonia, Br disappeared and about 6% of nitrogen in the form of amine group was incorporated at the surface. This result can be considered as a clear fingerprint of the Br substitution by the amine group, thus illustrating the efficiency of the proposed method for functionalization of polymer surfaces.

Functional polymer surfaces for controlling cell behaviors

Thorough understanding of how to control cell behaviors including cell adhesion, orientation, migration and differentiation on an artificial surface is critical in materials and life sciences such as advanced biomedical engineering, tissue engineering, and cell-based bioassay. In nature, extracellular matrix (ECM) plays an important role in controlling cell behaviors. It can not only provide the cells with mechanical support but also profoundly affect cell functions such as metabolism, movement and transport process. Functional polymer surface exhibits superior advantages over many other materials for use as artificial ECM owing to its excellent mechanical properties, abundant chemical species and remarkable capability to form various topographical surfaces. In particular, surface chemistry, mechanical properties and topography of these functional polymers are found to be three major parameters for effective control of cell behaviors. This paper comprehensively reviews the fundamental understanding of functional polymer surfaces for controlling cell behaviors. Different fabrication methods to achieve functional polymer surfaces and the parameters for effective control of cell behaviors are discussed. The future prospects and challenges particularly in cell biomedical engineering are also discussed at the end of this review paper.

Functional patterned coatings by thin polymer film dewetting

An approach for the fabrication of functional polymer surface coatings is introduced, where micro-scale structure and surface functionality are obtained by means of self-assembly mechanisms. We illustrate two main applications of micro-patterned polymer surfaces obtained through dewetting of bilayers of thin polymer films. By tuning the physical and chemical properties of the polymer bilayers, micro-patterned surface coatings could be produced that have applications both for the selective attachment and patterning of proteins and cells, with potential applications as biomaterials, and for the collection of water from the atmosphere. In all cases, the aim is to achieve functional coatings using approaches that are simple to realize, use low cost materials and are potentially scalable.

Surface Structuring Meets Orthogonal Chemical Modifications: Toward a Technology Platform for Site-Selectively Functionalized Polymer Surfaces and BioMEMS.

A manufacturing process for the site-selective modification of structured (bio)material surfaces with two different polymers/biomolecules is presented. In the first step, a chemical surface contrast is created (e.g., a gold-on-silicon contrast obtained by colloidal lithography), and is combined with two orthogonal surface reactions for polymer/biomolecule immobilization. To demonstrate this, an antimicrobial SMAMP polymer and a protein-repellent polyzwitterion were site-selectively surface-immobilized on the gold-silicon structures. By varying the structure spacing and the surface architecture, structure-property relationships for the interaction of these bifunctional polymer surfaces with bacteria and proteins were obtained (studied by fluorescence microscopy, atomic force microscopy, surface plasmon resonance spectroscopy, and antimicrobial assays). At 1 μm spacing, a fully antimicrobially active bifunctional material was obtained, which also near-quantitatively reduced protein adhesion. As the process is generally applicable to polymers/biomolecules with aliphatic CH-groups, it is an interesting platform technology for site-selectively functionalized bifunctional (Bio)MEMS.

Surface functionalization of high free-volume polymers as a route to efficient hydrogen separation membranes

A controlled growth of nanometric defect-free polydopamine layers leads to its novel demonstration as a hydrogen selective material.

Nanostructuring applications for functionalization of polymer surfaces with focused ion beam

Nanostructuring applications for functionalization of polymer surfaces with focused ion beam

Curved hierarchically micro–micro structured polypropylene surfaces by injection molding

Structural hierarchy of polymer surfaces has been of central interest due to its diverse surface functionalities. However, the research on hierarchically structured polymer surfaces has been focused on planar surfaces even though applications may also be variously curved. This study demonstrates the fabrication of curved rigid polymer surfaces with precisely controlled hierarchical microstructures. The surface structuration was made on an aluminum foil with a microworking robot, and polypropylene replicas were produced by injection molding. Depending on the mold structuration procedure, the curved mold can have either radially or vertically oriented structures. Both convex and concave curvatures were here applied to spherically and cylindrically curved surfaces. A simple structure protection technique was applied to support the structures during mechanical bending of the foil. The planar hierarchically microstructured polypropylene surfaces were characterized to exhibit superhydrophobicity, and similar structures were obtained on the curved surfaces. Introducing the curvature to the hierarchically structured surfaces may further widen the applicability of functionalized polymer surfaces.

Characterization and comparison of N‐, O‐, and N+O‐functionalized polymer surfaces for efficient (HUVEC) endothelial cell colonization

Surface modifications are often required to enhance cell adhesion and growth around implanted biomaterials. This study compares various functionalization processes in their ability to create high densities of oxygen‐ and/or nitrogen‐containing functional groups, mostly on a polymeric biomaterial, polyethylene terephthalate (PET). Primary amine (NH2)‐rich surfaces were prepared by low‐pressure plasma‐polymerization (L‐PPE:N), plasma modification (functionalized PET, “PETf”), chemical vapour deposition (Parylene diX AM), and grafting of polyallylamine (PAAm). Plasma polymerization was also used to obtain oxygen‐rich (L‐PPE:O) as well as hybrid (L‐PPE:O,N) films, which were respectively compared to oxygen‐rich tissue culture polystyrene (TCP) and hybrid (Primaria™) culture plates. Compositions and bond types were studied by X‐ray photoelectron spectroscopy. Finally, the effect of each surface on cell adhesion and growth was assessed using human umbilical vein endothelial cells (HUVECs). Amine‐containing surfaces manifested a wide [NH2] range, up to 8.9%. Hybrid surfaces, Primaria™ and L‐PPE:O,N, showed lower [NH2] in spite of high [N], suggesting more varied and complex functionalities. Except for Parylene, all O‐ and NH2‐rich surfaces promoted HUVEC adhesion and growth similarly, despite differing chemical compositions. Primaria™ showed the best cell behavior, but L‐PPE:O,N did not reproduce this apparent synergistic effect. To conclude, both N‐ and O‐rich surfaces displayed good cell‐colonization properties, particularly plasma polymers, while “hybrid” surfaces appear somewhat ambiguous and call for further investigation.

Dopamine-assisted deposition of lubricating and antifouling coatings on polyurethane surfaces by one-pot ATRP and click chemistry

Poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) and poly(N,N′-dimethyl-(methylmethacryloyl ethyl) ammonium propanesulfonate) (PDMAPS) were grafted on polyurethane (PU) surfaces by one-pot ATRP and click chemistry in order to improve the lubricating and antifouling properties. The successful grafting of PMPC and PDMAPS was confirmed by X-ray photoelectron spectroscopy. The immobilization of zwitterionic polymer brushes significantly improved the surface hydrophilicity and lubricating property of PU. In addition, the protein and bacteria adsorption on the modified PU surfaces were reduced greatly due to the presence of hydrated layer around the zwitterionic groups. The present surface modification approach was simple and versatile for functionalization of polymer surfaces.