Advanced antistatic/anticorrosion coatings prepared from polystyrene composites incorporating dodecylbenzenesulfonic acid‐doped SiO2@polyaniline core–shell microspheres

We present the preparation of advanced antistatic and anticorrosion coatings of polystyrene (PS) incorporating a suitable amount of dodecylbenzenesulfonic acid (DBSA)‐doped SiO₂@polyaniline (SP) core–shell microspheres. First, aniline‐anchored SiO₂ (AS) microspheres that were about 850 nm in diameter were synthesized using the conventional base‐catalyzed sol–gel process with tetraethyl orthosilicate in the presence of N‐[3‐(trimethoxysilyl)propyl]aniline. SP core–shell microspheres were then synthesized by chemical oxidative polymerization of aniline monomers with ammonium persulfate as an oxidizing agent in the presence of the AS microspheres. The polyaniline shell thickness of the as‐prepared core–shell microspheres was estimated to be about 120 nm. The AS and SP microspheres were further characterized using Fourier transform infrared spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy. The as‐synthesized DBSA‐doped SP core–shell microspheres were then blended into PS using N‐methyl‐2‐pyrrolidone as solvent and then cast onto a cold–rolled steel (CRS) electrode to obtain antistatic and anticorrosion coatings with a thickness of about 10 µm. The corrosion protection efficiency of the as‐prepared coating materials on the CRS electrode was investigated using a series of systematic electrochemical measurements under saline conditions. The enhanced corrosion protection ability of the PS/SP composite coatings may be attributed to the formation of a dense passive metal oxide layer induced by the redox catalytic effect of the polyaniline shell of the as‐synthesized core–shell microspheres, as evidenced by electron spectroscopy for chemical analysis and SEM observations. Moreover, the PS composite coating containing 10 wt% of the SP core–shell microspheres showed an electrical resistance of about 3.65 × 10⁹Ω cm^?2, which meets the requirements for antistatic applications. Copyright © 2012 Society of Chemical Industry     

Preparation of monodisperse fluorescent core–shell polymer microspheres with functional groups in the shell layer by two‐stage distillation–precipitation polymerization

Monodisperse crosslinked core–shell micrometer‐sized microspheres bearing a brightly blue fluorescent dye, carbazole, and containing various functional groups in the shell layers were prepared by a two‐stage distillation–precipitation polymerization in acetonitrile in the absence of any stabilizer. Commercial divinylbenzene (DVB), containing 80 vol.% of DVB, was polymerized by distillation–precipitation in acetonitrile without any stabilizer using 2,2′‐azobisisobutyronitrile (AIBN) as the initiator for the first stage of polymerization which resulted in monodisperse polyDVB microspheres used as the core. Several functional monomers, including 2‐hydroxyethyl methacrylate and acrylonitrile together with N‐vinylcarbazole blue fluorescent comonomer, were incorporated into the shell layers with AIBN as initiator during the second stage of polymerization. The resultant core–shell polymer microspheres were characterized using scanning electron microscopy, Fourier transform infrared spectroscopy, UV‐visible spectroscopy and fluorescence spectroscopy. Copyright © 2006 Society of Chemical Industry     

Preparation of core–shell poly(acrylic acid)/polystyrene/SiO2 hybrid microspheres

Core–shell poly(acrylic acid)/polystyrene/SiO₂ (PAA/PS/SiO₂) hybrid microspheres were prepared by dispersion polymerization with three stages in ethanol and ethyl acetate mixture medium. Using vinyltriethoxysilane (VTEOS) as silane agent, functional silica particles structured vinyl groups on surfaces were prepared by hydrolysis and polycondensation of tetraethoxysilane and VTEOS in core stage. Then, the silica particles were used as seeds to copolymerize with styrene and acrylic acid sequentially in shell stage I and stage II to form PAA/PS/SiO₂ hybrid microspheres. Transmission electron microscope results show that most PAA/PS/SiO₂ hybrid microspheres are about 40 nm in diameter, and the silica cores are about 15 nm in diameter, which covered with a layer of PS about 7.5‐nm thick and a layer of PAA about 5‐nm thick. This core–shell structure is also conformed by Fourier transform infrared spectroscopy, X‐ray photoelectron spectroscopy, and differential scanning calorimetry. FTIR results show that silica core, PS shell, and PAA outermost shell are bonded by covalents. In the core–shell PAA/PS/SiO₂ hybrid microsphere, the silica core is rigidity, and the PAA outermost shell is polarity, while the PS layer may work as lubricant owning to its superior processing rheological property in polymer blending. These core–shell PAA/PS/SiO₂ hybrid microspheres have potential as new materials for polar polymer modification. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1729–1733, 2006     

Synthesis,characterization, and in vitro release of ibuprofen from poly(MMA‐HEMA) copolymeric core–shell hydrogel microspheres for biomedical applications

This article describes the development of a new crosslinked poly(methyl methacrylate‐2‐hydroxyethyl methacrylate) copolymeric core–shell hydrogel microsphere incorporated with ibuprofen for potential applications in bone implants. Initially poly(methyl methacrylate) (PMMA) core microspheres were prepared by free‐radical initiation technique. On these core microspheres, 2‐hydroxyethyl methacrylate (HEMA) was polymerized by swelling PMMA microspheres with the HEMA monomer by using ascorbic acid and ammonium persulfate. Crosslinking monomers such as ethylene glycol dimethacrylate (EGDMA) has also been included along with HEMA for polymerization. By this technique, it was possible to obtain core–shell‐type microspheres. The core is a hard PMMA microsphere having a hydrophilic poly(HEMA) shell coat on it. These microspheres are highly hydrophilic as compared to PMMA microspheres. The size of the hydrogel microspheres almost doubled when swollen in benzyl alcohol. These microspheres were characterized by various techniques such as optical microscopy, scanning electron microscopy, Fourier‐transformed infrared spectroscopy, thermogravimetric analysis, and differential scanning calorimetry. The particle size of both microspheres was analyzed by using Malvern Master Sizer/E particle size analyzer. The in vitro release of ibuprofen from both microspheres showed near zero‐order patterns. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 3045–3054, 2002; DOI 10.1002/app.10310     

Preparation of core–shell glass bead/polysulfone microspheres with two‐step sol–gel process

Core–shell microspheres made from glass beads as the core phase and polysulfone (PSf) as the shell phase can act as an absorbent in the separation process or a supporter for chemical reactions. Based on phase‐inversion principles, a two‐step sol–gel method was developed in this work in which ether was added first and H₂O was added second to a PSf‐containing dimethyformamide (DMF) solution to help PSf solidify on the surface of glass beads. The results from scanning electron microscopy, Fourier transform IR, and X‐ray photoelectron spectroscopy showed that a dense layer of PSf (thin to several microns) was coated on the glass beads and the core–shell microspheres were almost monodispersed. The utilization percentages of the glass beads and PSf were high as 100 and 80%, respectively. The thickness of the PSf membrane was calculated to be about 4.3 μm. To obtain well‐monodispersed microspheres, the practical volume ratio of ether to DMF was recommended to be larger than 4.5. The results suggested that the two‐step sol–gel method is a highly efficient process for preparation of glass bead/PSf core–shell microspheres. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 99: 3365–3369, 2006     

Palladium‐Iminodiacetic Acid Immobilized on pH‐Responsive Polymeric Microspheres: Efficient Quasi‐Homogeneous Catalyst for Suzuki and Heck Reactions in Aqueous Solution

The pH‐responsive core‐shell microspheres of poly(styrene‐co‐methylacrylic acid) (PS‐co‐PMAA) containing a polystyrene (PS) core and a poly(methylacrylic acid) (PMAA) shell are synthesized by one‐stage soap‐free copolymerization and the catalyst system palladium‐iminodiacetic acid (IDA‐Pd) is immobilized on the outer shell‐layer of the core‐shell microspheres to form the quasi‐homogeneous and easily accessible catalyst PS‐co‐PMAA‐IDA‐Pd. This quasi‐homogeneous PS‐co‐PMAA‐IDA‐Pd catalyst is highly dispersed in the reaction medium just like a homogeneous one and can be separated like a heterogeneous catalyst by adjusting the pH of the reaction medium. Suzuki reactions employing the quasi‐homogeneous PS‐co‐PMAA‐IDA‐Pd catalyst are efficiently performed in water as the sole solvent under mild conditions such as room temperature. The PS‐co‐PMAA‐IDA‐Pd catalyst is also used in Heck reactions of a wide range of aryl halides with styrene and proves to be efficient in aqueous solution. The PS‐co‐PMAA‐IDA‐Pd catalyst has a low leaching loss and can be reused at least 4 times without loss of activity.     

Stimuli‐responsive recognition of BSA‐imprinted poly vinyl acetate grafted calcium alginate core‐shell hydrogel microspheres

Poly vinyl acetate grafted calcium alginate hydrogel microspheres were prepared with bovine serum albumin (BSA) as molecular template. The microspheres exhibited homogeneous and core‐shell structure according to different preparation strategy. The rebinding and swelling property of microspheres showed responsiveness toward ionic strength, temperature, and pH. It was found the highest separation factor of 1.85 and imprinting efficiency of 1.75 when the Ca²⁺ ionic strength was 1.25 and 0.34 mol/kg, respectively. The separation factor was found decreased as temperature grew from 29 to 45°C while the imprinting efficiency reached a peak value at about 37°C. Separation factor of BSA imprinted microspheres at different pH was also recorded and two peaks were found, which were considered to be caused by the similar swollen state due to ionic and covalent crosslinking structure of modified microspheres. The recognition responsiveness is suggested to be influenced by environmental effects due to the changing in imprints' configuration at different swollen states. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Adaptive Polymeric Coatings with Self‐Reporting and Self‐Healing Dual Functions from Porous Core–Shell Nanostructures

In biological system, early detection and treatment at the same moment is highly required. For synthetic materials, it is demanding to develop materials that possess self‐reporting of early damage and self‐healing simultaneously. This dual function is achieved in this work by introducing an intelligent pH‐responsive coatings based on poly(divinylbenzene)‐graft‐poly(divinylbenzene‐co‐methacrylic acid) (PDVB‐graft‐P(DVB‐co‐AA)) core–shell microspheres as smart components of the polymer coatings for corrosion protection. The key component, synthesized PDVB‐graft‐P(DVB‐co‐AA) core–shell microspheres are porous and pH responsive. The porosity allows for encapsulation of the corrosion inhibitor of benzotriazole and the fluorescent probe, coumarin. Both loading capacities can be up to about 15 wt%. The polymeric coatings doped with the synthesized microspheres can adapt immediately to the varied variation in pH value from the electrochemical corrosion reaction and release active molecules on demand onto the damaged cracks of the coatings on metal surfaces. It leads simultaneously to the dual functions of self‐healing and self‐reporting. The corrosion area can be self‐reported in 6 h, while the substrate can be protected at least for 1 month in 3.5 wt% NaCl solution. These pH‐responsive materials with self‐reporting and self‐healing dual functions are highly expected to have a bright future due to their smart, long‐lasting, recyclable, and multifunctional properties.     

Layer‐by‐layer assembled hydrogel nanocomposite film with a high loading capacity

The layer‐by‐layer assembly technique is a method that widely used in the preparation of nanostructured multilayer ultrathin films. We fabricated a hydrogel nanocomposite film by alternating the deposition of a core–shell poly[(dimethylimino)(2‐hydroxy‐1,3‐propanedily) chloride] (PDMIHPC)–laponite solution and poly(acrylic acid). The growth of the deposition procedure was proven by ultraviolet–visible spectroscopy and spectroscopic ellipsometry. The surface morphology of the films was observed by scanning electron microscopy. The films could reversibly load and release methylene blue (MB) dye, which was used as an indicator. It took about 4.5 h to reach loading equilibrium at pH 9.0. The loading capacity of the film for MB was as large as 4.48 μg/cm² per bilayer because of the introduction of the core–shell PDMIHPC–laponite as a film component. Nearly 90% of MB was released at pH 3.0 or in a 300 mM NaCl solution within 2.5 h. The loading and release processes were greatly influenced by the ionic strength and pH value of the MB solution. The hydrogel nanocomposite film showed good pH‐triggered loading‐release reversibility and suggested potential applications in controlled drug‐delivery systems and smart materials. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39352.     

A simple route to prepare pomegranate‐like polystyrene‐based microspheres with high porosity

Pomegranate‐like polystyrene‐based microspheres with high porosity were successfully prepared via a simple route involving two steps. The first step was the preparation of polystyrene‐based microspheres with multi‐cores and a non‐porous shell via suspension polymerization of divinylbenzene and vinylbenzyl chloride. Nitrogen sorption failed to characterize the pore structure of the microspheres because of the non‐porous shell, but the results of Hg intrusion indicated that the pore volume of the microspheres was 0.36 cm³ g^?1. The second step was post crosslinking of the microspheres derived from the first step. Extensive porosity was generated in the shell and the pomegranate‐like structure of the microspheres remained almost unchanged. The results showed that the pore volumes of the final products derived from N₂ sorption and Hg intrusion were 0.54 cm³ g^?1 and 0.66 cm³ g^?1, respectively. Overall, this provides a simple and feasible route to biomimetic preparation of pomegranate‐like polystyrene‐based microspheres with high porosity. Copyright © 2011 Society of Chemical Industry     

Self‐assembly of pH‐responsive acrylate latex particles at emulsion droplets interface

The self‐assembly of pH‐responsive poly (methyl methacrylate‐co‐acrylic acid) latex particles at emulsion droplet interfaces was achieved. Raising pH increases the hydrophilicity of the latex particles in situ and the latex particle acts as an efficient particulate emulsifier self‐assembling at emulsion droplet interface at around pH 10–11 but exhibits no emulsifier activity at higher pH. This effect can be reversibly induced simply by varying the aqueous phase pH and thus the latex emulsifier can be reassembled. The effect factors, including the aqueous phase pH, the surface carboxyl content, ζ‐Potential of the latex particles and oil phase solvent have been investigated. Using monomer as oil phase, the latex particles could stabilize emulsion droplets during polymerization and cage‐like polymer microspheres with hollow core/porous shell structure were obtained after polymerization. The mechanism of the latex particles self‐assembly was discussed. The morphologies of emulsion and microspheres were characterized by optical microscopy, scanning electron microscopy, and transmission electron microscopy. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

An improved phase‐inversion process for the preparation of silica/poly[styrene‐co‐(acrylic acid)] core–shell microspheres: synthesis and application in the field of polyolefin catalysis

Spherical and well‐dispersed silica/poly[styrene‐co‐(acrylic acid)] (SiO₂/PSA) core–shell particles have been synthesized using an improved phase‐inversion process. The resulting particles were successfully used as supports for polyolefin catalysts in the production of polyethylene with broad molecular weight distribution. Through the vapor phase, instead of the liquid phase in the traditional process, a non‐solvent was introduced into a mixture of micrometer‐sized SiO₂ and PSA solution. The core–shell structure of the resulting SiO₂/PSA microspheres was confirmed using optical microscopy, scanning electron microscopy, Fourier transfer infrared spectrometry, thermogravimetric analysis and measurement of nitrogen adsorption/desorption isotherms. In order to avoid agglomeration of particles and to obtain a good dispersion of the SiO₂/PSA core–shell microspheres, the non‐solvent was added slowly. As the concentration of PSA solution increased, the surface morphology of the core–shell particles became looser and more irregular. However, the surface area and the pore volume remained the same under varying PSA concentrations. The SiO₂/PSA core‐shell microspheres obtained were used as a catalyst carrier system in which the core supported (n‐BuCp)₂ZrCl₂ and the shell supported TiCl₄. Ethylene/1‐hexene copolymerization results indicated that the zirconocene and titanium‐based Ziegler–Natta catalysts were compatible in the hybrid catalyst, showing high activities. The resulting polyethylene had high molecular weight and broad molecular weight distribution. Copyright © 2010 Society of Chemical Industry     

Preparation of novel hybrid inorganic–organic hollow microspheres via a self‐template approach

BACKGROUND: Hollow microspheres, especially biodegradable polymeric microspheres, have attracted considerable attention due to their particular characteristics. Up to now, microspheres have been prepared via various strategies, for instance the template synthesis method and the self‐assembly process. However, economic, novel and simple methods to prepare hollow microspheres are still being sought. RESULTS: Phosphazene‐containing microspheres, which contain self‐assembled core‐shell structures, were prepared at high colloid contents using an ultrasonic bath via a self‐template approach. Along with the controlled self‐degradation of the internal core, the corresponding hybrid inorganic–organic hollow microspheres appeared. The mechanism was evidenced by means of transmission and scanning electron microscopy, cross‐polarization with magic angle spinning NMR, Fourier transform infrared spectroscopy, X‐ray diffraction and thermogravimetric analysis. CONCLUSION: It was clarified that the phosphazene‐containing microspheres could be formed and stably dispersed without aggregation even at high colloid contents using the ultrasonic bath method and the microspheres contain self‐assembled core–shell structures. Along with the controlled self‐degradation of the internal core, the corresponding hollow microspheres appeared. The mechanism of this preparation is of great significance because it is completely different from the conventional template synthesis method and the self‐assembly process. The absence of any stabilizing agent and special templates might inspire creative imagination in the design of new morphologies of micro‐ and nanostructures. Copyright © 2007 Society of Chemical Industry     

Monodisperse Silica‐Polymer Core‐Shell Microspheres via Surface Grafting and Emulsion Polymerization

We describe a flexible method for preparing monodisperse silica‐polystyrene core‐shell microspheres. In this method, silica nanoparticles grafted with 3‐(trimethoxysilyl)propyl methacrylate (MPS) were employed as seeds in an emulsion polymerization. The thickness of the shells could be changed through varying the amount of the monomer. The monodispersity and diameters of the core‐shell microspheres were found to depend on the size of the grafted silica nanoparticles and the concentration of emulsifier. In addition, we investigated the formation mechanism of the core‐shell microspheres.

Schematic outline of the experimental procedure and TEM image of the monodisperse silica/PS core‐shell microspheres; inset: grafted silica nanoparticles (scale bar = 200 nm).     

α‐Amylase immobilized by Fe3O4/poly(styrene‐co‐maleic anhydride) magnetic composite microspheres: Preparation and characterization

Fe₃O₄/poly(styrene‐co‐maleic anhydride) core–shell composite microspheres, suitable for binding enzymes, were prepared using magnetite particles as seeds by copolymerization of styrene and maleic anhydride. The magnetite particles were encapsulated by polyethylene glycol, which improved the affinity between the magnetite particles and the monomers, thus showing that the size of the microspheres, the amount of the surface anhydrides, and the magnetite content in the composite are highly dependent on magnetite particles, comonomer ratio, and dispersion medium used in the polymerization. The composite microspheres, having 0.08–0.8 μm diameter and containing 100–800 μg magnetite/g microspheres and 0–18 mmol surface‐anhydride groups/g microsphere, were obtained. Free α‐amylase was immobilized on the microspheres containing reactive surface‐anhydride groups by covalent binding. The effects of immobilization on the properties of the immobilized α‐amylase [magnetic immobilized enzyme (MIE)] were studied. The activity of MIE and protein binding capacity reached 113,800 U and 544.3 mg/g dry microspheres, respectively. The activity recovery was 47.2%. The MIE had higher optimum temperature and pH compared with those of free α‐amylase and showed excellent thermal, storage, pH, and operational stability. Furthermore, it can be easily separated in a magnetic field and reused repeatedly. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 95: 328–335, 2005     

Coaxial electrohydrodynamic atomization toward large scale production of core‐shell structured microparticles

In this work, a double‐nozzle coaxial electrohydrodynamic atomization (CEHDA) system was designed as an instructive case toward large‐scale production of core‐shell microspheres. The effect of nozzle‐to‐nozzle distance was investigated to reveal that the interference between neighboring nozzles significantly affect the product quality in terms of morphology and core‐shell structure. Optimal spacing indicated that ～3000 nozzle/m² packing density may be achieved with minimum interference of electric field from neighboring nozzle by adjusting the nozzle‐to‐nozzle distance greater than 0.018 m. The proposed multi‐scale model also showed that the X‐component of electric field strength (E_x) at the region near side nozzles increases with increasing nozzle number, and the bending of jets/sprays at the side may be reduced by using dummy nozzle at the edge side. The model could guide the design of multi‐nozzle CEHDA system for production of core‐shell microparticles in large‐scale. © 2017 American Institute of Chemical Engineers AIChE J, 63: 5303–5319, 2017     

Multi‐responsive polymeric microcontainers for potential biomedical applications: synthesis and functionality evaluation

Temperature and pH responsive poly(N‐isopropylacrylamide‐co‐methacrylic acid) (P(NIPAAm‐co‐MAA)) microcontainers with encapsulated magnetic nanoparticles in the shell were prepared by a two‐stage distillation precipitation polymerization. PMAA@Fe₃O₄/P(NIPAAm‐co‐MAA) core–shell nanoparticles were synthesized by the second‐stage polymerization of NIPAAm, MAA and N, N′‐methylenebisacrylamide as crosslinker in the presence of magnetic nanoparticles and PMAA as core. These novel triple‐functional microcontainers were prepared by selective removal of the PMAA core in water. Daunorubicin hydrochloride (DNR) was loaded into the microcontainers and the release profile was studied by UV–visible spectroscopy. The synthesized nanostructures were characterized with transmission and scanning electron microscopy, X‐ray diffraction and Fourier transform infrared spectroscopy. The magnetic properties were evaluated by vibrating sample magnetometry. The shrink and swelling behavior was studied by dynamic light scattering. Copyright © 2012 Society of Chemical Industry     

Protein‐imprinted polyurethane‐grafted calcium alginate hydrogel microspheres

Protein‐imprinted polyurethane‐grafted calcium alginate hydrogel microspheres were prepared and characterized. The samples were investigated with optical microscopy, scanning electron microscopy, ¹³C‐NMR, and Fourier transform infrared spectroscopy. We proved that polyurethane side chains were successfully grafted, and this led to a relatively rough and dense surface. The samples exhibited better swelling durability when applied in specific adsorption tests. The adsorption kinetic and recognition properties indicated that the imprinted modified microspheres had excellent rebinding affinity toward the target proteins. Moreover, the influence of the preassembly pH, rebinding pH, and grafting ratio on the adsorption capacity and imprinting efficiency (IE) were systematically investigated. The study results suggest that the modified samples possessed a higher IE toward the target protein under the optimum pH and grafting ratio. Upon polyurethane grafting modification, the alginate hydrogel microspheres showed improved mechanical stability and recognition specificity. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42140.     

Methanol‐Tolerant Heterogeneous PdCo@PdPt/C Electrocatalyst for the Oxygen Reduction Reaction

We have prepared carbon‐supported nanoparticles with the heterogeneous structure of a PdPt shell on a PdCo core which are effective for the oxygen reduction reaction (ORR) in the presence of methanol. The preparation was based on the galvanic replacement reaction between PdCo/C nanoparticles and PtCl₄^2–, a method of general utility which can be extended to the preparation of other core‐shell electrocatalysts. The heterogeneous PdCo‐core and PtPd‐shell architecture was confirmed by multiple techniques including high resolution transmission electron microscopy, energy dispersive X‐ray spectroscopy, powder X‐ray diffraction and X‐ray photoelectron spectroscopy. The activity of the PdCo@PdPt/C catalyst in ORR was evaluated in acidic solutions both with and without methanol (0.1 M). The results showed four to sixfold increases in activity over a standard Pt/C catalyst with no apparent loss of catalyst stability. It is inferred that the strain effect from the lattice mismatch between the shell and core components is the major contributor for the enhancement of ORR activity and selectivity.     

Fabrication and properties of core‐shell structure P(LLA‐CL) nanofibers by coaxial electrospinning

In this article, core‐shell structure nanofibers were fabricated by coaxial electrospinning with biodegradable copolymer Poly(L ‐Lactic‐ε‐Caprolactone) [P(LLA‐CL) 50 : 50] as shell and bovine serum albumin (BSA) as core. Morphology and microstructure of the nanofibers were characterized by scanning electron microscopy and transmission electron microscopy. The mechanical properties were investigated by stress‐strain tests. In vitro degradation rates of the nanofibrous membranes were determined by measuring their weight loss when immersed in phosphate‐buffered saline (pH 7.4) for a maximum of 14 days. Release behavior of BSA was measured by an ultraviolet‐visible spectroscopy, and the results demonstrated that BSA could release from P(LLA‐CL) nanofibers in a steady manner. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009