Oxidative graft polymerization of aniline on Si(100) surface modified by plasma polymerization of glycidyl methacrylate

Modification of argon plasma-pretreated Si(100) surfaces via plasma polymerization of glycidyl methacrylate(GMA), followed by reactive coupling of the epoxide groups of the plasma deposited GMA chains with aniline, and finally by oxidative graft polymerization of aniline was carried out. An alternative approach involved the modification of the argon plasma-pretreated Si(100) surfaces via plasma polymerization of glycidyl methacrylate(GMA), followed by direct oxidative graft polymerization of aniline and thermal curing. The compositions and chemical states of the modified Si surfaces were characterized by X-ray photoelectron spectroscopy (XPS). The two methods of surface modification of the Si(100) surfaces produced similar results. The protonation-deprotonation behavior, the interconvertible intrinsic redox states, and the metal reduction behavior (the electroless plating of Pd from the Pd(II) ion solution) of the grafted polyaniline (PANI) chains on the Si(100) surface were grossly similar to those of the PANI homopolymer. The coupling of PANI to the covalently tethered GMA chains on the Si(100) surface was suggested by the cohesive failure inside the epoxy adhesive that was applied to the modified Si surface in an attempt to peel off the PANI layer from the GMA plasma-polymerized Si (GMA-pp-Si) substrate.     

Preparation of superhydrophobic surfaces by cauliflower‐like polyaniline

Cauliflower‐like polyaniline (PANI) was successfully prepared using an interfacial polymerization method. By modification with polydimethylsiloxane (PDMS) using chemical vapor deposition method, the surface wettability of cauliflower‐like PANI can be tailored to be superhydrophobic with a water contact angle of 160.4°. The deposition of the low‐surface‐energy silicon coating originated from PDMS pyrolysis on the cauliflower‐like PANI was confirmed by X‐ray photoelectron spectroscopy and Fourier Transform Infrared Spectroscopy. The changes in thermal stability and conductivity of the as‐prepared PANI before and after PDMS treatment were also investigated by thermogravimetric analysis and using a four‐probe method. Compared with nanofiber‐shaped PANI by electrodepositing polymerization, the PDMS‐treated cauliflower‐like PANI has superior surface wettability. Our study may open a new way for fabrication of superhydrophobic surfaces by developing novel nanostructured PANI. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39767.     

Electroactive polymer patterns with metal incorporation on a polymeric substrate

Electroactive polymer patterns on a polymeric substrate were fabricated using either a UV lithographic approach or plasma polymerization method. For the lithographic patterning technique, photosensitive thin films comprising polyaniline (PANI) coatings on viologen‐grafted low‐density polyethylene (LDPE) substrates were first prepared. The composite film was subsequently exposed to UV irradiation through a mask. Under UV irradiation, reactions between PANI and viologen occurred, resulting in the conversion of the PANI to a doped state. The PANI micropatterns were developed by using N‐methylpyrrolidinone (NMP) to dissolve the soluble‐unexposed (and hence undoped) parts. The use of Ar plasma treatment of the composite film instead of UV irradiation was not successful in inducing the doping reaction between PANI and viologen. On the other hand, plasma polymerization was shown to be another convenient way for the selective surface deposition of aniline polymer on the surface of the LDPE substrate through a mask. The further incorporation of metal/metal ions in both the PANI‐viologen and plasma polymerized aniline system was successfully carried out on the micropatterns. Polym. Eng. Sci. 44:2061–2069, 2004. © 2004 Society of Plastics Engineers.     

A novel hydrogen peroxide sensor based on Ag nanoparticles decorated polyaniline/graphene composites

A novel electrochemical sensor based on Ag nanoparticles (AgNPs) decorated polyaniline/graphene composites (PANI/G) is developed, which can be used for sensitive determination of H₂O₂. For the construction of the H₂O₂ sensor, polyaniline (PANI) is first electrodeposited on the surface of graphene (G) to form PANI/G, and then horseradish peroxidase (HRP) loaded on AgNPs (HRP/AgNPs) is immobilized on to the PANI/G. H₂O₂ can be catalyzed by HRP to generate current response which can be significantly enhanced by AgNPs, and thus the PANI/G based sensor can be utilized for the detection of H₂O₂. Under the optimized conditions, the proposed H₂O₂ sensor exhibits wide linear response to H₂O₂ concentration ranging from 0.25 to 2.25 mM with a detection limit of 0.03 mM (signal‐to‐noise ratio of 3), and it also shows high selectivity and reproducibility. The method is simple and cost‐effective, and can be a promising candidate as the sensitive sensing platform for H₂O₂. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42409.     

Anticoagulant surface prepared by the heparinization of ionic polyurethane film

We present a new method for heparinization on the surface of polyurethane. The segmented polyurethane was first modified with an epoxide monomer and followed by a ring‐opening reaction with diethanolamine to introduce sufficient hydroxyl groups on the surface of cast film. On this film surface, a cationic monomer was grafted by using tetravalent Cerium salt as an initiator. Heparin was immobilized in high efficiency on the ionized surface through static interactions in aqueous solution. The structure of ionized and heparinized surfaces were characterized by attenuated total reflectance infrared spectroscopy (ATR–FTIR) and electron spectroscopy for chemical analysis (ESCA) spectra. The platelet‐rich plasma (PRP) contacting test and the platelet‐poor plasma (PPP) clotting time measurements showed that the immobilized heparin retained its strong anticoagulant property. The release of heparin from film into salt solution was also studied, and it was found that only a small portion of heparin (10–20%) was released over a period as long as 10 h. It is expected that this new method for surface heparinization can be used to prepare antithrombogenic materials with long‐term stability. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 382–390, 2000     

Electrochemical Characteristics and Performance of Platinum Nanoparticles Supported by Vulcan/Polyaniline for Oxygen Reduction in PEMFC

We report a Pt/Vulcan carbon–polyaniline (VC–PANI) catalyst for the oxygen reduction reaction (ORR). This electrocatalyst was prepared from Pt nanoparticles supported by a VC–PANI composite substrate. Electrochemical performance was measured using potentiostat/galvanostats technique and a proton exchange membrane fuel cell (PEMFC) test station. The electrochemical properties of the electrodes were characterized using linear sweep voltammetry, AC impedance spectroscopy and chronoamperometry. Electrochemical characterization by hydrogen adsorption/desorption cyclic voltammetry and CO stripping voltammetry indicates that the electrochemical active surface areas of the Pt/VC–PANI are comparable to the commercial catalyst. The performance of the Pt/VC–PANI and Pt/C(E‐TEK) + PANI electrocatalysts were found to be 1.82 and 1.33 times higher than of the Pt/C(E‐TEK) electrode. The surface morphologies of the electrodes were characterized by using scanning electron microscopy (SEM). PANI has a fibrous structure and the improved performance was attributed to the PANI effect and synergistic effects between the carbon Vulcan and the PANI fiber. These results indicate that Pt/VC–PANI is a promising catalyst for the ORR in PEMFCs using an H₂/O₂ feed.     

Microwave plasma reactions of imidazole on poly(vinyl chloride) surfaces: A spectroscopic study

Although there are various forms of energy available for conducting surface and interfacial reactions, microwave plasma energy is an attractive means for surface modifications because it is fast and it usually does not alter bulk properties. In this study, a closed‐system microwave plasma reactor was used to react imidazole molecules to poly(vinyl chloride) (PVC) surfaces. Newly created surfaces were analyzed using attenuated total reflectance (ATR) Fourier‐transformed infrared (FTIR) spectroscopy. These studies show that surface reactions on PVC are heavily dependent upon a prior thermal history of the PVC substrate. It appears that the plasma reactions on hot‐pressed PVC not only result in the development of CH₂ linkages, but a significant increase of crystallinity in the hot‐pressed PVC inhibits the reactivity of imidazole to the PVC surface. On the other hand, for a solvent‐cast PVC with a significantly lower surface crystalline phase content, imidazole reacts to the PVC surface through CC bond opening. The amount of imidazole reacted to the PVC surface changes with the depth from the surface. Using quantitative ATR FTIR spectroscopy, imidazole content can be quantified, and its concentrations are in the 10⁻⁶ mol/cm² range at about 0.8–1.2 μm for the PVC surface. A mechanism of the PVC–imidazole reactions is also proposed. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 1–6, 1999     

Surface modification of ePTFE vascular grafts with O‐carboxymethylchitosan

O‐Carboxymethylchitosan (OCMCS) was covalently immobilized onto expanded poly(tetrafluoroethylene) (ePTFE) vascular graft using a photosensitive hetero‐bifunctional crosslinking reagent, 4‐azidobenzoic acid. 4‐Azidobenzoic‐bonded OCMCS (Az‐OCMCS) was prepared by reaction between an acid group of the crosslinking reagent and a free amino group of OCMCS. Immobilization was accomplished by irridiating the A₃‐OCMCS coating on the substrate surface with ultraviolet light. Electron spectroscopy and water contact angle were used to characterize that OCMCS had been bonded on the ePTFE vascular graft surface. The hydrophilicity of ePTFE was enhanced greatly by surface bonding with OCMCS. Platelet adhesion assay showed that the ePTFE vascular surface bonded with OCMCS demonstrated good blood‐compatibility. Copyright © 2003 Society of Chemical Industry     

Preparation of protein microarrays on non‐fouling and hydrated poly(ethylene glycol) hydrogel substrates using photochemical surface modification

BACKGROUND: Conventional protein microarrays prepared on hard, dry substrates, such as glass and silicone, have several limitations, as proteins may easily denature and lose their structure. To overcome such problems, the fabrication of wet protein microarrays on non‐fouling and hydrated PEG‐based hydrogels was investigated. RESULT: Bovine serum albumin (BSA) and glucose oxidase (GOX), chosen as model proteins, were covalently immobilized on PEG hydrogel surfaces via 5‐azidonitrobenzoyloxy N‐hydroxysuccinimide, a photoreactive bifunctional linker. Successful fixation of the bifunctional linker and subsequent immobilization of the proteins on the PEG hydrogel surfaces were confirmed with X‐ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) studies. GOX immobilized on the hydrogel surface maintained approximately 50% of its initial activity after 24 h when left in dry conditions, but maintained only 20% when immobilized on a dry substrate. Photochemical fixation combined with photolithography produced well‐defined protein micropatterns with sizes ranging from 50–500 µm, and molecular recognition‐mediated specific binding between biotin and streptavidin was successfully assayed using microarrays on PEG hydrogels. CONCLUSION: A protein‐repellent PEG hydrogel surface was photochemically modified to covalently immobilize proteins and create protein microarrays. The use of hydrated hydrogels as substrates for protein microarrays could minimize the deactivation of proteins in dry conditions, and the non‐fouling property of PEG hydrogels allows the passivation step of protein microarray preparation to be skipped. Copyright © 2008 Society of Chemical Industry     

Synthesis and characterization of crosslinked chitosan immobilized on bentonite and its grafted products with polyaniline

Chitosan immobilized bentonite (CIB) namely chitosan‐coated bentonite (5% chitosan content) was synthesized in 2% acetic acid solution, followed by crosslinking, using epichlorohydrien (ECH). The so‐obtained crosslinked chitosan immobilized on bentonite (CIB‐ECH) and CIB composites were grafted with polyaniline (PANI) through oxidative‐radical copolymerization using ammonium peroxydisulfate in acidic medium to produce PANI‐grafted crosslinked chitosan immobilized on bentonite (PANI‐g‐CIB‐ECH) and PANI‐grafted‐chitosan immobilized on bentonite (PANI‐g‐CIB) composites, respectively. The resultant composites were characterized by using X‐ray diffraction (XRD), thermo gravimetric analysis/differential scanning calorimetry, scanning electron microscopy, Fourier transform infrared (FTIR), and electrical conductivity. XRD and FTIR analyses indicate that chitosan was not intercalated into the silicate layer. Also the electrical conductivity elucidates that the grafted composites fall in the range required for the application as electrostatic dissipation. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41078.     

A photochemical method for immobilization of azidated dextran onto aminated poly(ethylene terephthalate) surfaces

BACKGROUND: Dextran, a bacterial polysaccharide, has been reported to be as good as poly(ethylene glycol) in its protein‐rejecting and cell‐repelling abilities. In addition, the multivalent nature of dextran is advantageous for surface grafting of biologically active molecules. We report here a method to photochemically bind dextran hydrogel films to aminated poly(ethylene terephthalate) (PET) surfaces in aqueous media using a heterobifunctional crosslinker, 4‐azidobenzoic acid. In order to achieve this, dextran was first functionalized with the crosslinker using carbodiimide chemistry followed by photo‐crosslinking and immobilization onto the nucleophile‐rich aminated PET surfaces. RESULTS: The presence of the immobilized dextran on PET was verified by attenuated total‐reflection Fourier transform infrared spectroscopy, X‐ray photoelectron spectroscopy, scanning electron microscopy and contact angle measurements. The grafted surface was highly hydrophilic due to the heavily hydrated polysaccharide network on the surface as demonstrated by the near zero water contact angle. CONCLUSION: A photochemical method for surface immobilization of dextran onto aminated PET using aryl azide chemistry is a facile technique to generate highly hydrophilic and more hemocompatible surfaces. The aryl nitrenes generated by photolysis produce a metastable, electron‐deficient intermediate, azacycloheptatetraene, which is believed to be responsible for the simultaneous crosslinking of dextran and its immobilization onto the aminated PET surface. The aryl azide chemistry reported here for dextran could be useful as a versatile technique for surface modification of other nucleophile‐rich polymers to create dextran‐ or similar polysaccharide‐immobilized surfaces. Copyright © 2007 Society of Chemical Industry     

Self-assembly of thiolated cyanine aggregates on Au(111) and Au nanoparticle surfaces

Heptamethinecyanine J-aggregates display sharp, intense fluorescence emission making them attractive candidates for developing a variety of chem-bio-sensing applications. They have been immobilized on planar thiol-covered Au surfaces and thiol-capped Au nanoparticles by weak molecular interactions. In this work the self-assembly of novel thiolated cyanine (CNN) on Au(111) and citrate-capped AuNPs from solutions containing monomers and J-aggregates has been studied by using STM, XPS, PM-IRRAS, electrochemical techniques and Raman spectroscopy. Data show that CNN species adsorb on the Au surfaces by forming thiolate-Au bonds. We found that the J-aggregates are preferentially adsorbed on the Au(111) surface directly from the solution while adsorbed CNN monomers cannot organize into aggregates on the substrate surface. These results indicate that the CNN-Au interaction is not able to disorganize the large J-aggregates stabilized by π-π stacking to optimize the S-Au binding site but it is strong enough to hinder the π-π stacking when CNNs are chemisorbed as monomers. The optical properties of the J-aggregates remain active after adsorption. The possibility of covalently bonding CNN J-aggregates to Au planar surfaces and Au nanoparticles controlling the J-aggregate/Au distance opens a new path regarding their improved stability and the wide range of biological applications of both CNN and AuNP biocompatible systems.     

Adhesion enhancement of evaporated copper on HDPE surface modified by plasma polymerization of glycidyl methacrylate

Surface modification of high‐density polyethylene (HDPE) surfaces by plasma polymerization of glycidyl methacrylate (GMA) (the pp‐GMA‐HDPE surfaces), in the absence and presence of Ar plasma pre‐activation of the HDPE substrates, was carried out to enhance the adhesion of the polymer with evaporated copper. THe FTIR and X‐ray photoelectron spectroscopy (XPS) results suggested that the epoxide functional groups on the pp‐GMA‐HDPE surfaces had been preserved to various extents, depending on the RF power used during plasma polymerization. Ar plasma pre‐activation of the HDPE surface led to the strong interaction of the pp‐GMA layer with the HDPE substrate. GMA plasma polymerization at low RF powers and in the presence of Ar plasma pre‐activation was shown to be an effective method for enhancing the adhesion of HDPE with the evaporated Cu. An optimum adhesion strength of about 16 N/cm was achieved between the evaporated Cu and the pp‐GMA‐HDPE surface prepared by plasma polymerization of GMA at 5 W, 100 Pa, 20 sccm for 5 s on the HDPE surface pre‐activated by Ar plasma at 35 W, 100 Pa 20 sccm for 20 s. The adhesion enhancement of the Cu/pp‐GMA‐HDPE assemblies in the presence of Ar plasma pre‐activation of the HDPE substrate was attributed to the covalent bonding of the plasma‐polymerized GMA (pp‐GMA) layer with the HDPE surface, the preservation of the epoxide functional groups in the pp‐GMA layer, and the spatial interactions of pp‐GMA chains with the evaporated Cu matrix.     

Plasma‐enhanced deposition of silver nanoparticles onto polymer and metal surfaces for the generation of antimicrobial characteristics

Silver nanoparticle thin layers were deposited onto formaldehyde‐radio frequency (RF)‐plasma‐functionalized medical‐ and food‐grade silicone rubber, stainless steel, and paper surfaces. The silver deposition was carried out under ex situ plasma conditions using the Tollen's reaction. Results from survey and high‐resolution electron spectroscopy for chemical analysis, scanning electron microscopy (SEM), atomic force microscopy (AFM), and energy dispersive X‐ray spectroscopy investigations confirmed the presence of thin silver layers on the plasma‐exposed and subsequently modified substrate surfaces. In addition, SEM and AFM demonstrated the nanoparticle‐based morphology of the deposited layers. Our results showed that thin macromolecular layers bearing aldehyde functionalities can be deposited onto silicone rubber, stainless steel, and paper surfaces. The bactericidal properties of the silver‐coated surfaces were demonstrated by exposing them to Listeria monocytogenes. No viable bacteria were detected after 12 to 18 h on silver‐coated silicone rubber surfaces. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1411–1422, 2004     

XPS study of aged polyaniline films

In this article, a study of the aging of conducting Polyaniline–Polystyrene blends using X‐ray photoelectron spectroscopy (XPS) and UV‐visible‐near IR analysis is presented. The physicochemical results are compared to those obtained by electrical measurements. XPS results confirm the existence of an oxidation process also deduced by the electrical conductivity studies. The N1s and S2p core level spectra decomposition allows to show that a deprotonation process and cyclization of tertiary amine occur during aging. The absorption spectrum shows a decrease of delocalized charges and the apparition of localized polarons after a long aging time. All these mechanisms are responsible of the electrical conductivity decrease observed during aging at elevated temperature. The results are presented for films of PANI–CSA–PSt blends, but the conclusions can be extended to pure conducting PANI–CSA films. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3730–3736, 2003     

Immobilization of active α‐chymotrypsin on RF‐plasma‐functionalized polymer surfaces

Various polymeric surfaces (polyester, polyethylene, polystyrene) were functionalized under oxygen and dichlorosilane‐RF‐cold‐plasma environments and were employed as substrates for further in situ derivatization reactions and immobilization of α‐Chymotrypsin. The nature and morphology of the derivatized substrates and the substrates with immobilized enzymes were analyzed using survey and high‐resolution X‐ray photoelectron spectroscopy, attenuated total reflectance‐fourier transform infrared (ATR‐FTIR), laser desorption fourier transform ion cyclotron resonance mass spectrometry, chemical derivatization, and atomic force microscopy (AFM) techniques. It was demonstrated that the tacticity of the polystyrene substrate did not notably influence the activity of the immobilized enzyme, however, spacer molecules intercalated between the polymeric substrates (e.g., polyethylene) and the enzyme significantly increased the enzyme activity (comparable with that of the free enzyme). Computer‐aided conformational modeling of the substrate‐spacer systems indicated that the longer the spacer chain, the greater the mobility of the enzyme. It is suggested that the greater mobility of the enzyme molecules is responsible for the enhanced activity. It has also been shown that the stability of the immobilized enzyme systems was good; they retained their activity during several washing/assay cycles. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 1783–1796, 2000     

Self‐cleaning,titanium dioxide based,multilayer coating fabricated on polymer and glass surfaces

A photocatalytic self‐cleaning titanium dioxide (TiO₂) coating was prepared as a multilayer coating structure by the spin‐coating method. Three substrate materials (two thermoplastics and one ceramic) were used: (1) high‐density polyethylene (HDPE), (2) poly(vinyl chloride), and (3) borosilicate glass (BK7). The multilayer structure consisted of a polyurethane protective layer on the substrate, two layers of photocatalytic TiO₂ on the protective layer, and finally immobilized TiO₂ particles bound in a diluted polyurethane dispersion. Photocatalytically active surfaces were achieved by reactive oxygen‐plasma surface etching of the fabricated coatings. The structure and properties of the coating surfaces were characterized with scanning electron microscopy and contact‐angle measurements. The coatings on HDPE and BK7 were rendered superhydrophilic by an oxygen‐plasma treatment. The photocatalytic activity and self‐cleaning properties of the prepared surfaces were studied with palmitic acid (model soil), the degradation of which was confirmed by contact‐angle measurements and gas chromatography analysis. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Patterned conductive polyaniline films fabricated using lithography and in situ polymerization

In this article, we describe a novel bottom‐up technique for the preparation of transparent conductive films of polyaniline (PANI). A UV‐curable photoresist was formulated containing an acrylate‐endcapped urethane oligomer [UA(PPG400)], acrylic acid, a photoinitiator, and a reactive diluent (tripropylene glycol diacrylate), and the lithography techniques were used to pattern the structure with line widths/spaces of 100 μm/100 μm, 10 μm/10 μm, and 5 μm/5 μm on a polyethylene terephthalate substrate. The carboxylic acid units on the surface of the patterned photoresist interacted with the aniline monomer units to form anilinium complexes; using ammonium persulfate as a chemical oxidant, we then synthesized a layer of conductive PANI on the surface of the patterned resist through in situ polymerization. The optimal conductivity of the PANI conductive film was ca. 10 S/cm. The thin film was characterized, and its physical properties investigated using Fourier transform infrared spectroscopy, UV–Vis spectroscopy, differential scanning calorimetry, optical and atomic force microscopy, and four‐point probe conductivity measurements. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Preparation and characterization of polyaniline,multiwall carbon nanotubes,and starch bionanocomposite material for potential bioanalytical applications

In this article, we are reporting the preparation and characterization of a multi‐component integrated nanocomposite material by the combination of a naturally occuring biocompatible biopolymer (Starch—a type of polysaccharide), functional conjugated synthetic polymer (Polyaniline “PANI”—a type of intrinsic conducting polymer) and nanosize tubular conducting template material (multiwalled carbon nanotubes “MWCNTs”—a type of carbonaceous nanotube structure). Comparative studies of the four material systems viz. system‐1: PANI, system‐2: PANI/MWCNTs, system‐3: PANI/Starch, and system‐4: PANI/MWCNTs/Starch have been carried out to understand the physical and chemical characteristics by using following instrumental techniques; UV‐Visible spectroscopy, fourier infrared spectroscopy, Raman, X‐ray diffraction, scanning electron microscopy, transmission electron microscopy, BET‐surface area, conductivity, thermal gravimetric analysis, differential scanning calorimetry, and cyclic voltammetry. Proposed nanocomposite material, PANI/MWCNTs/Starch has nanosized integrated porous morphology (∼200–300 nm) with interconnected architecture, while simultaneously having good conductivity and better electroactivity. Moreover, the presence of hydroxyl functionality empowers it with good dispersion ability which is further supported by good biodegradability and biocompatibility. These properties together attest the proposed system for promising applications in biosensors and screen printed electrode ink formulation. POLYM. COMPOS., 38:496–506, 2017. © 2015 Society of Plastics Engineers     

Surface‐functionalization of plasma‐treated polystyrene by hyperbranched polymers and use in biological applications

Nitrogen plasma was used to amino‐functionalize polystyrene surfaces, which were further modified via the selective introduction of polyamines suitable for the immobilization of biological compounds. This chemical modification was carried out using a multifunctional amine compound linked to glutaraldehyde, leading to the formation of hyperbranched structures at the surface. Up to three generations of branched polymers at the polystyrene (PS) surface were created by successive addition of the functional compounds. Amine functions introduced at the surface were labeled with 2,3,4,5,6‐pentafluorobenzaldehyde and analyzed by X‐ray photoelectron spectroscopy (XPS), confirming the successful attachment of each generation of branching. Finally, bovine serum albumin and trypsin were immobilized on N₂‐plasma‐treated PS modified with different amounts of branched graft polymer and found to remain bioactive after immobilization. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009