Chemical Vapor Deposition Polymerization Research Articles

Orientation Determination of a Hybrid Peptide Immobilized on CVD-Based Reactive Polymer Surfaces

Antimicrobial peptides (AMPs), due to their unique structure/function relationship, have great opportunities to be developed into novel diagnostic and therapeutic agents for a variety of pathogens and illnesses. Often such peptides are administered using powder or suspension, limiting their reusability or recyclability. Immobilization of these antimicrobial peptides on biotic/abiotic surfaces may circumvent such disadvantages, but such immobilization is likely to not only change the peptide secondary structures and their orientations but also ultimately affect functionality. In order to better understand surface-bound structures of AMPs on abiotic surfaces, cecropin A (1–8)–melittin (1–18) hybrid peptides were chemically immobilized on polymer surfaces prepared by chemical vapor deposition (CVD) polymerization. Measurements by sum frequency generation (SFG) vibrational spectroscopy and circular dichroism were used to characterize the peptides immobilized on the CVD-based polymer in situ. In addition, coarse-grained molecular dynamics (MD) simulations were used to understand the orientation of these peptides on the molecular level. Simulation results were highly consistent with experimental data. Results indicated that, unlike other linear peptides immobilized on similar abiotic surfaces, this hybrid peptide immobilized on CVD-based polymer surfaces exhibited two bending points. Such conclusions help further understand the role surface immobilization for such unique molecules.

Metal-Organic Covalent Network Chemical Vapor Deposition for Gas Separation.

The chemical vapor deposition (CVD) polymerization of metalloporphyrin building units is demonstrated to provide an easily up-scalable one-step method toward the deposition of a new class of dense and defect-free metal-organic covalent network (MOCN) layers. The resulting hyper-thin and flexible MOCN layers exhibit outstanding gas-separation performances for multiple gas pairs.

Polymer Thin Films and Surface Modification by Chemical Vapor Deposition: Recent Progress.

Chemical vapor deposition (CVD) polymerization uses vapor phase monomeric reactants to synthesize organic thin films directly on substrates. These thin films are desirable as conformal surface engineering materials and functional layers. The facile tunability of the films and their surface properties allow successful integration of CVD thin films into prototypes for applications in surface modification, device fabrication, and protective films. CVD polymers also bridge microfabrication technology with chemical and biological systems. Robust coatings can be achieved via CVD methods as antifouling, anti-icing, and antihydrate surfaces, as well as stimuli-responsive or biocompatible polymers and novel nanostructures. Use of low-energy input, modest vacuum, and room-temperature substrates renders CVD polymerization compatible with thermally sensitive substrates and devices. Compared with solution-based methods, CVD is particularly useful for insoluble materials, such as electrically conductive polymers and controllably crosslinked networks, and has the potential to reduce environmental, health, and safety impacts associated with solvents. This review discusses the relevant background and selected applications of recent advances by two methods that display and use the high retention of the organic functional groups from their respective monomers, initiated CVD (iCVD) and oxidative CVD (oCVD) polymerization.

Effects of surface modification of Nd-Fe-B powders using parylene C by CVDP method on the properties of anisotropic bonded Nd–Fe–B magnets

This paper presents effects of surface modification of Nd–Fe–B powders using parylene C by means of chemical vapor deposition polymerization (CVDP) on the properties of anisotropic bonded Nd–Fe–B magnets. It can be well verified from SEM images and EDS analysis that the surface of Nd–Fe–B powder is coated with thin parylene C films. The maximum energy product ((BH)max), degree of alignment (DOA), actual density and corrosion resistance of parylene Nd–Fe–B magnets prepared at room temperature are much higher than that of non-parylene Nd–Fe–B magnets. (BH)max, DOA and actual density of parylene Nd–Fe–B magnets (70kJ/m3, 0.342, 5.82g/cm3) prepared at room temperature under 578MPa are improved by 18.6%, 4.6%, 2.1% and 27.3%, 29.1%, 7.8% compared with non-parylene Nd‐Fe‐B magnets prepared at 140°C (59kJ/m3, 0327, 5.70g/cm3) and room temperature (55kJ/m3, 0.265, 5.40g/cm3), respectively. Additional, the improvement of actual density and the room temperature process also solve problems such as powders’ sticking wall, non-uniform powder filling, non-uniform magnetic properties, seriously mould damage, short life cycle of mould and so on, which exists during warm compaction process. Parylene Nd–Fe–B magnets have better corrosion resistance and worse mechanical properties than that of non-parylene Nd–Fe–B magnets. The reason for the improvement of magnetic properties and actual density is the low friction cofficient of parylene C films, which results in lower frictional resistance and better lubricating property of parylene Nd–Fe–B powders.

Surfaces, Interfaces, and Rock and Roll

Dear Reader, Advanced Materials Interfaces is now in its third year. The positive response from our authors has resulted in the frequency of publication now increasing to 24 issues a year. Areas showing strong growth in submissions include photovoltaics, electrochemistry, biofilms, membranes, device junctions, 2D materials, strongly correlated systems, heterogeneous catalysis, and colloidal systems, always in conjunction with top-level research on interface technologies and effects. Advanced Materials Interfaces also has new members on its Advisory Board. We welcome Lifeng Chi (FUNSOM Institute, Soochow University), Hongjin Fan (Nanyang Technological University), and Taolei Sun (Wuhan University of Technology). The full listing of the Editorial Advisory Board be found here. The journal has quickly become truly interdisciplinary, as this selection of recent review articles demonstrates: Bio-Interface of Conducting Poly­mer-Based Materials for Neuroregeneration. Recent Advancements in All-Vanadium Redox Flow Batteries. Superamphiphobic Coatings with High Transmittance: Structure, Fabrication, and Perspective. Metal-Free Click Chemistry Reactions on Surfaces. Biomedical Applications of Functionalized ZnO Nanomaterials: from Biosensors to Bioimaging. Interfacial Friction Control. In 2016 we will also be publishing a regular section focusing on deposition methods such as Chemical Vapor Deposition (CVD), Atomic Layer Deposition (ALD), and related techniques. Francis Maury (CNRS, Toulouse) will coordinate input from the International Advisory Board for this section. In this context, Karen Gleason's Review on CVD polymerization, A Route Towards Sustainability Through Engineered Polymeric Interfaces, available here, is particularly worth a mention. 2016 will also see Advanced Materials Interfaces receive its first Impact Factor, and it is clear that this will reflect the outstanding work already published in the journal. Access was free to all in 2014 and 2015 but now, in January 2016, this introductory period comes to an end and all content is available through a paid subscription. While access to all manuscripts published until December 2015 is retained, if you wish to continue reading the excellent work published in Advanced Materials Interfaces going forward, please encourage your librarian to ensure a subscription is in place. You can do this by completing the recommendation form, here. We are indebted to our Advisory Board members, authors, reviewers, and readers, for entrusting the journal with exceptional papers, and for helping to improve them further. We wish you all the best for a healthy and productive year in 2016. Kind regards, P.S. The editorial team is happy to receive any input and comments at advmatinterfaces@wiley.com

Immobilization of enzyme on a polymer surface

We successfully immobilized enzymes onto polymer surfaces via covalent bonds between cysteine groups of the enzyme and dibromomaleimide functionalities present at the polymer surface. In this work, we used nitroreductase (NfsB) as a model enzyme molecule. The polymers were prepared by chemical vapor deposition (CVD) polymerization, resulting in surfaces with dibromomaleimide groups. NfsB variants were engineered so that each NfsB molecule only has one cysteine group on the enzyme surface. Two different NfsB constructs were studied, with cysteines at the positions of H360 and V424, respectively. A combination of sum frequency generation (SFG) vibrational and attenuated total reflectance Fourier transformed infrared (ATR-FTIR) spectroscopies were used to deduce the orientation of the immobilized enzymes on the surface. It was found that the orientation of the immobilized enzymes is controlled by the position of the cysteine residue in the protein. The NfsB H360C construct exhibited a similar orientational behavior on the polymer surface as compared to that on the self-assembled monolayer surface, but the NsfB V424C construct showed markedly different orientations on the two surfaces.

Selective and Reversible Binding of Thiol-Functionalized Biomolecules on Polymers Prepared via Chemical Vapor Deposition Polymerization.

We use chemical vapor deposition polymerization to prepare a novel dibromomaleimide-functionalized polymer for selective and reversible binding of thiol-containing biomolecules on a broad range of substrates. We report the synthesis and CVD polymerization of 4-(3,4-dibromomaleimide)[2.2]paracyclophane to yield nanometer thick polymer coatings. Fourier transformed infrared spectroscopy and X-ray photoelectron spectroscopy confirmed the chemical composition of the polymer coating. The reactivity of the polymer coating toward thiol-functionalized molecules was confirmed using fluorescent ligands. As a proof of concept, the binding and subsequent release of cysteine-modified peptides from the polymer coating were also demonstrated via sum frequency generation spectroscopy. This reactive polymer coating provides a flexible surface modification approach to selectively and reversibly bind biomolecules on a broad range of materials, which could open up new opportunities in many biomedical sensing and diagnostic applications where specific binding and release of target analytes are desired.

Free-standing nanomembranes based on selective CVD deposition of functional poly-p-xylylenes.

The precise engineering of ultrathin nanofilms with variable functionality remains an unmet challenge in nanotechnology. We report a strategy for generating free-standing nanomembranes based on the selective chemical vapor deposition polymerization of functional [2.2]paracyclophanes on micropatterned self-assembled monolayers of alkanethiolates on gold. This fabrication strategy can yield microstructured nanofilms that are between 2 and 5 nm thick. Subsequent release from the substrate results in free-standing nanoscale membranes with controlled pore size and geometry. The process allows for modification of important functional parameters, such as ultrasmall membrane thickness, membrane pore geometry, and chemical functionality.

Fabrication and properties of iron-based soft magnetic composites coated with parylene via chemical vapor deposition polymerization

This paper focuses on novel iron-based soft magnetic composites synthesis utilizing low friction factor parylene C films to coat iron powder via chemical vapor deposition polymerization. The morphology, magnetic properties, density, and chemical stability of parylene insulated iron particles were investigated. The coated parylene insulating layer was characterized by scanning electron microscopy and energy dispersive X-ray spectroscopy. The thickness of parylene C film is averagely 300 nm according to the results of transmission electron microscopy. Parylene C film uniformly coated the powder surface resulting in reducing the permeability imaginary part, increasing electrical resistivity and increasing the operating frequency of the synthesized magnets. It was shown that the parylene C coated compacts exhibited noticeably higher density compared to the epoxy resin coated compacts at the same pressure, suppress at 800 MPa increased the density by 17.02%. The result of Tafel curves indicated that the resistance of the iron particles to corrosion by NaCl solution is obviously improved after being insulated with parylene C film.

Highly Flexible Energy Storage Electrodes Based on In Situ Synthesis of Graphene/Polyselenophene Nanohybrid Materials

ABSTRACTA new class of graphene–polyselenophene (PSe) hybrid nanocomposite was successfully synthesized using an in situ synthetic method. The synthesized graphene–PSe nanocomposite exhibited unique properties including a large voltage window, high conductivity, and good mechanical properties. The graphene–PSe nanohybrid reduced the dynamic resistance of electrolyte ions and enabled high charge–discharge rates, thereby enabling high-performance supercapacitance. The results were attributed to synergetic effects between graphene and conducting polymers (CPs), which enhanced charge transport, surface area, and hybrid supercapacitance by combining the properties of electrolytic double-layer capacitors (EDLCs) with those of psedocapacitors. Additionally, a flexible supercapacitor based on the graphene–PSe nanohybrid was successfully demonstrated. To fabricate binder-free supercapacitors, chemical vapor deposition (CVD) and vapor deposition polymerization (VDP) methods were employed. The fabricated all-solid-state supercapacitor exhibited outstanding mechanical and electrochemical performance, even after several bending motions. The novel graphene–PSe nanocomposite material is promising for new energy storage and conversion applications.

Tailoring the LCST of thermosensitive hydrogel thin films deposited by iCVD.

Using the iCVD (initiated chemical vapor deposition) polymerization technique, we generated a library of thermosensitive thin film hydrogels in the physiological temperature range. The library shows how a specific hydrogel with a desired temperature response can be synthesized via the copolymerization of three main components: (a) the main thermosensitive monomer, which determines the temperature range of the LCST; (b) the comonomer, which modulates the temperature according to its hydrophilic/hydrophobic behavior; and (c) the cross-linker, which determines the swelling degree and the polymer chain mobility of the resulting hydrogel. The thermosensitive thin films included in the library have been characterized by the water contact angle (WCA), revealing a switchable hydrophobic/hydrophilic behavior depending on the temperature and a decrease in the WCA with the incorporation of hydrophilic moieties. Moreover, a more accurate characterization by quartz crystal microbalance (QCM) is performed. With temperature and flow control, the switchable swelling properties of the thermosensitive thin films (due to the polymer mixture transition) can be recorded and analyzed in order to study the effects of the comonomer moieties on the lower critical solution temperature (LCST). Thus, the LCST tailoring method has been successfully used in this paper, and thermoresponsive thin films (50 nm in thickness) have been deposited by iCVD, exhibiting LCSTs in the 32-49 °C range. Due to the presented method's ability to tailor the LCST in the physiological temperature range, the developed thermoresponsive films present potential biosensing and drug delivery applications in the biomedical field.

A Route Towards Sustainability Through Engineered Polymeric Interfaces

Chemical vapor deposition (CVD) of polymer films represent the marriage of two of the most important technological innovations of the modern age. CVD as a mature technology for growing inorganic thin films is already a workhorse technology of the microfabrication industry and easily scalable from bench to plant. The low cost, mechanical flexibility, and varied functionality offered by polymer thin films make them attractive for both macro and micro scale applications. This review article focuses on two energy and resource efficient CVD polymerization methods, initiated Chemical Vapor Deposition (iCVD) and oxidative Chemical Vapor Deposition (oCVD). These solvent‐free, substrate independent techniques engineer multi‐scale, multi‐functional and conformal polymer thin film surfaces and interfaces for applications that can address the main sustainability challenges faced by the world today.

In Situ Synthesis of Graphene/Polyselenophene Nanohybrid Materials as Highly Flexible Energy Storage Electrodes

A new class of graphene–polyselenophene (PSe) hybrid nanocomposite was successfully synthesized using an in situ synthetic method. The synthesized graphene–PSe nanocomposite exhibited unique properties including a large voltage window, high conductivity, and good mechanical properties. The graphene–PSe nanohybrid reduced the dynamic resistance of electrolyte ions and enabled high charge–discharge rates, thereby enabling high-performance supercapacitance. The results were attributed to synergetic effects between graphene and conducting polymers (CPs), which enhanced charge transport, surface area, and hybrid supercapacitance by combining the properties of electrolytic double-layer capacitors (EDLCs) with those of psedocapacitors. Additionally, a flexible supercapacitor based on the graphene–PSe nanohybrid was successfully demonstrated. To fabricate binder-free supercapacitors, chemical vapor deposition (CVD) and vapor deposition polymerization (VDP) methods were employed. The fabricated all-solid-state sup...

Bioactive surface functionalization

Reactive chemical vapor deposition (CVD) polymerization provides a substrate-independent platform for effective functionalization of virtually any solid substrates, flat, or curved, even with complex geometries. This article reviews bioactive surface functionalization strategies based on CVD polymerization and highlights commonly used surface chemistries. These reactions include alkyne–azide “click” chemistry, reactions of active esters with amine, aldehydes/ketones with hydrazides and alkoxyamines, thiols with alkenes and alkynes and surface-initiated atom transfer radical polymerization. The resulting biofunctional surface coatings can facilitate orthogonal immobilization of more than one type of ligand on a substrate. CVD polymer coatings with nanoscale thicknesses are widely applicable in biomedical applications and can be easily integrated into microand nanodevice fabrication. VC 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40315.

Orthogonal surface functionalization through bioactive vapor‐based polymer coatings

ABSTRACTReactive chemical vapor deposition (CVD) polymerization provides a substrate‐independent platform for effective functionalization of virtually any solid substrates, flat, or curved, even with complex geometries. This article reviews bioactive surface functionalization strategies based on CVD polymerization and highlights commonly used surface chemistries. These reactions include alkyne–azide “click” chemistry, reactions of active esters with amine, aldehydes/ketones with hydrazides and alkoxyamines, thiols with alkenes and alkynes and surface‐initiated atom transfer radical polymerization. The resulting biofunctional surface coatings can facilitate orthogonal immobilization of more than one type of ligand on a substrate. CVD polymer coatings with nanoscale thicknesses are widely applicable in biomedical applications and can be easily integrated into micro‐ and nanodevice fabrication. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40315.

25th Anniversary Article: CVD Polymers: A New Paradigm for Surface Modifi cation and Device Fabrication

Well-adhered, conformal, thin (<100 nm) coatings can easily be obtained by chemical vapor deposition (CVD) for a variety of technological applications. Room temperature modification with functional polymers can be achieved on virtually any substrate: organic, inorganic, rigid, flexible, planar, three-dimensional, dense, or porous. In CVD polymerization, the monomer(s) are delivered to the surface through the vapor phase and then undergo simultaneous polymerization and thin film formation. By eliminating the need to dissolve macromolecules, CVD enables insoluble polymers to be coated and prevents solvent damage to the substrate. CVD film growth proceeds from the substrate up, allowing for interfacial engineering, real-time monitoring, and thickness control. Initiated-CVD shows successful results in terms of rationally designed micro- and nanoengineered materials to control molecular interactions at material surfaces. The success of oxidative-CVD is mainly demonstrated for the deposition of organic conducting and semiconducting polymers.

Co-immobilization of Biomolecules on Ultrathin Reactive Chemical Vapor Deposition Coatings Using Multiple Click Chemistry Strategies

Immobilization of biomolecules, such as proteins or sugars, is a key issue in biotechnology because it enables the understanding of cellular behavior in more biological relevant environment. Here, poly(4-ethynyl-p-xylylene-co-p-xylylene) coatings have been fabricated by chemical vapor deposition (CVD) polymerization in order to bind bioactive molecules onto the surface of the material. The control of the thickness of the CVD films has been achieved by tuning the amount of precursor used for deposition. Copper-catalyzed Huisgen cycloaddition has then been performed via microcontact printing to immobilize various biomolecules on the reactive coatings. The selectivity of this click chemistry reaction has been confirmed by spatially controlled conjugation of fluorescent sugar recognizing molecules (lectins) as well as cell adhesion onto the peptide pattern. In addition, a microstructured coating that may undergo multiple click chemistry reactions has been developed by two sequential CVD steps. Poly(4-ethynyl-p-xylylene-co-p-xylylene) and poly(4-formyl-p-xylylene-co-p-xylylene) have been patterned via vapor-assisted micropatterning in replica structures (VAMPIR). A combination of Huisgen cycloaddition and carbonyl-hydrazide coupling was used to spatially direct the immobilization of sugars on a patterned substrate. This work opens new perspectives in tailoring microstructured, multireactive interfaces that can be decorated via bio-orthogonal chemistry for use as mimicking the biological environment of cells.

Biofunctional Micropatterning of Thermoformed 3D Substrates

Mimicking the in vivo microenvironment of cells is a challenging task in engineering in vitro cell models. Surface functionalization is one of the key components providing biochemical cues to regulate the interaction between cells and their substrate. In this study, two different approaches yield biofunctional surface patterns on thermoformed polymer films. The first strategy based on maskless projection lithography enables the creation of grayscale patterns of biological ligands with a resolution of 7.5 μm in different shapes on a protein layer adsorbed on a polymer film. In the second strategy, polymer films are micropatterned with different functional groups via chemical vapor deposition polymerization. After thermoforming, both types of pattern can be decorated with proteins either by affinity binding or covalent coupling. The 3D microstructures retain the biofunctional patterns as demonstrated by selective cell adhesion and growth of L929 mouse fibroblasts. This combination of functional micropatterning and thermoforming offers new perspectives for the design of 3D cell culture platforms.

Formation of Poly(methyl methacrylate) Thin Films onto Wool Fiber Surfaces by Vapor Deposition Polymerization

Chemical vapor deposition (CVD) polymerization is a useful technique because of the possibility of forming very thin film of pure polymers on substrates with any geometric shape. In this work, thin films of poly(methyl methacrylate) or PMMA were formed on the surfaces of wool fabrics by a CVD polymerization process. Various polymerization initiators including dicumyl peroxide, tert-butyl peroxide, and potassium peroxydisulfate have been investigated to polymerize methyl methacrylate onto the surfaces of wool by the CVD polymerization. The wool fabrics were impregnated with initiators and were then exposed to MMA monomer vapor under vacuum at the boiling temperature of the monomer. Wool fabrics with vapor-deposited PMMA surfaces were characterized by elemental analysis, TGA, FTIR, disperse dye absorption, contact angles measurement, AFM, and SEM. PMMA-coated wool fabrics showed higher contact angle and absorbed more dyes than that of the control wool. It was evident from the results obtained by various characterization techniques that MMA was successfully polymerized and formed thin films on the surfaces of wool fabrics by all initiators investigated but the best results were achieved with tert-butyl peroxide.

Vapor-Deposited Parylene Photoresist: A Multipotent Approach toward Chemically and Topographically Defined Biointerfaces

Poly(4-benzoyl-p-xylylene-co-p-xylylene), a biologically compatible photoreactive polymer belonging to the parylene family, can be deposited using a chemical vapor deposition (CVD) polymerization process on a wide range of substrates. This study discovered that the solvent stability of poly(4-benzoyl-p-xylylene-co-p-xylylene) in acetone is significantly increased when exposed to approximately 365 nm of UV irradiation, because of the cross-linking of benzophenone side chains with adjacent molecules. This discovery makes the photodefinable polymer a powerful tool for use as a negative photoresist for surface microstructuring and biointerface engineering purposes. The polymer is extensively characterized using infrared reflection adsorption spectroscopy (IRRAS), scanning electron microscopy (SEM), and imaging ellipsometry. Furthermore, the vapor-based polymer coating process provides access to substrates with unconventional and complex three-dimensional (3D) geometries, as compared to conventional spin-coated resists that are limited to flat 2D assemblies. Moreover, this photoresist technology is seamlessly integrated with other functionalized parylenes including aldehyde-, acetylene-, and amine-functionalized parylenes to create unique surface microstructures that are chemically and topographically defined. The photopatterning and immobilization protocols described in this paper represent an approach that avoids contact between harmful substances (such as solvents and irradiations) and sensitive biomolecules. Finally, multiple biomolecules on planar substrates, as well as on unconventional 3D substrates (e.g., stents), are presented.