Atom Transfer Radical Polymerization Grafting Research Articles

Fibronectin adsorption on polystyrene sulfonate-grafted polyester using atomic force microscope.

Cell adhesion and growth over prostheses are strongly influenced by the adsorption and conformation of adhesive proteins from blood and extracellular matrix, such as fibronectin. This key behavior can be possibly exploited to develop a prosthetic ligament based on the surface bioactivation of biodegradable materials. In this work, surface functionalization was performed by grafting poly(sodium 4-styrene sulfonate) on polyethylene terephthalate and polycaprolactone using a thermal surface-initiated atom transfer radical polymerization grafting technique. The morphology and mechanical properties of the adsorbed fibronectin in the presence of albumin were studied by atomic force microscopy. The morphology of fibronectin on two kinds of polyester surfaces was similar. However, the study results showed a remarkable conformation change of fibronectin when adsorbed onto the nongrafted or grafted surface, leading to an increase in cell adhesion and organization in the second case. This research provided evidence of the relationship between the morphology change of fibronectin to the enhancement of the cell adhesion and spreading on the grafted surface of polyester.

Tunable plasticization of sustainable ethyl cellulose toward thermoplastic elastomers through ATRP grafting

Thermoplastic elastomers (TPEs) derived from sustainable cellulose and its derivatives have attracted a great deal of attention, because of their abundance, renewable nature, rigid backbone and good mechanical properties. To fabricate TPEs with tunable performance, a series of sustainable ethyl cellulose (EC)-grafted poly(methyl methacrylate (MMA)) (EC-g-P(MMA)) and poly(MMA-co-butyl methacrylate (BMA)) (EC-g-P(MMA-co-BMA)) were fabricated by way of atom-transfer radical polymerization (ATRP). By tuning the molar ratio of MMA/BMA in the copolymer side chains, tunable performance of TPEs with tunable glass transition temperatures (118–47.8°C) was achieved. The chemical structures of EC-bromide and EC graft copolymers were identifiable by Fourier transform infrared spectroscopy and hydrogen-1 (1H) nuclear magnetic resonance spectroscopy. The EC graft copolymers exhibited a higher molecular weight and good thermal stability and mechanical properties. These results suggested that these tunable-performance copolymers with a sustainable cellulose backbone and an acrylate side chain were potential candidates for service as TPEs in some applications.

Vapor Phase Modification for Selective Enrichment of Grafted Styrene/Acrylonitrile onto Carbon Nanotubes Via ATRP

Nitric acid vapor phase oxidation of multi-walled carbon nanotubes (MWCNTs) was proposed as a promising technique to fabricate poly styrene-co-acrylonitrile (SAN)-grafted-CNTs via atom transfer radical polymerization (ATRP). The in-situ ATRP grafting approach was successfully employed to graft polystyrene (PS), SAN and polyacrylonitrile (PAN), onto the convex surfaces of pristine MWCNTs (PCNT) and acid-functionalized MWCNTs (FCNT). Fourier transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance (1H-NMR), and thermogravimetric analysis (TGA) confirmed the effectiveness of the modification via the ATRP grafting approach. The molar composition of acrylonitrile in the synthesized copolymer on the surface of CNTs for an FCNTs was calculated to be about 80% and 67.5% by 1H-NMR and TGA respectively, whereas the value is lower for PCNTs. Morphological studies showed that SAN-grafted FCNTs exhibit rougher surface morphology compared to the SAN-grafted PCNTs. Moreover, the higher diameter of the FCNTs indicated the higher polymer content, which was coated onto CNTs functionalized by vapor-phase oxidation. Therefore, the vapor phase oxidation strategy employed in this study could be utilized as a general method to prepare CNTs which can serve as an ATRP macroinitiator for the fabrication of various polymer grafted CNTs.

Surface-initiated atom transfer radical polymerization grafting from nanoporous cellulose gels to create hydrophobic nanocomposites.

Here, we present the preparation of hydrophobic nanoporous cellulose gel-g-poly(glycidyl methacrylate) (NCG-g-PGMA) nanocomposites by surface-initiated atom transfer radical polymerization (SI-ATRP) of glycidyl methacrylate (GMA) monomers and hydrophobic modification with pentadecafluorooctanoyl chloride (C7F15COCl) on the cellulose nanofibrils of the NCG. The successful grafting of PGMA and hydrophobic modification of C7F15CO– groups on the NCG was evaluated by Fourier transform infrared (FTIR) spectroscopy. X-ray diffraction (XRD) and scanning electron microscopy (SEM) confirmed that the SI-ATRP and hydrophobic modification did not change the microscopic morphology and structure of the NCG-g-PGMA nanocomposites. Dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA) showed remarkable thermomechanical properties and moderate thermal stability. The method has tremendous promise to use NCG as a platform for SI-ATRP and produce new functional NCG-based nanomaterials.

Improving the hydrophilic and antifouling properties of poly(vinyl chloride) membranes by atom transfer radical polymerization grafting of poly(ionic liquid) brushes

In this study, poly(1‐butyl‐3‐vinylimidazolium bromide) (PBVIm‐Br) was grafted onto the poly(vinyl chloride) (PVC) membrane surface via a 2‐step atom transfer radical polymerization (ATRP) reaction. Poly(2‐hydroxyethylmethacrylate) (PHEMA) was grafted onto the membrane surface by aqueous ATRP reaction; then, BVIm‐Br was introduced onto the surface of the PHEMA‐modified PVC membrane through traditional ATRP reaction. The analysis of surface chemistry confirmed the successful grafting of PHEMA and PBVIm‐Br on PVC membrane surface, and the grafting density (GD) of PBVIm‐Br gradually increased as the grafting time was prolonged. The modified membrane exhibited a positive charge and significantly enhanced surface hydrophilicity. The static water contact angle of the membrane surface decreased from 92.3° to 51.6° as the GD of the PBVIm‐Br brushes increased. Filtration experiments indicated that the water flux of the modified membrane increased with increasing GD, and their recovered fluxes were more than twice than the original. In addition, the total fouling ratio of the membranes decreased from 89% in M0 to 67% in M5, and most of the fouling was reversible as the GD of PBVIm‐Br brushes increased. These results indicated that the positive charged poly(ionic liquid) brushes featuring hydrophilic properties would have potential applications in membrane separation.

Preparation and Grafting Functionalization of Self-Assembled Chitin Nanofiber Film

Chitin is a representative biomass resource comparable to cellulose. Although considerable efforts have been devoted to extend novel applications to chitin, lack of solubility in water and common organic solvents causes difficulties in improving its processability and functionality. Ionic liquids have paid much attention as solvents for polysaccharides. However, little has been reported regarding the dissolution of chitin with ionic liquids. The author found that an ionic liquid, 1-allyl-3-methylimidazolium bromide (AMIMBr), dissolved chitin in concentrations up to ~4.8 wt % and the higher contents of chitin with AMIMBr gave ion gels. When the ion gel was soaked in methanol for the regeneration of chitin, followed by sonication, a chitin nanofiber dispersion was obtained. Filtration of the dispersion was subsequently carried out to give a chitin nanofiber film. A chitin nanofiber/poly(vinyl alcohol) composite film was also obtained by co-regeneration approach. Chitin nanofiber-graft-synthetic polymer composite films were successfully prepared by surface-initiated graft polymerization technique. For example, the preparation of chitin nanofiber-graft-biodegradable polyester composite film was achieved by surface-initiated graft polymerization from the chitin nanofiber film. The similar procedure also gave chitin nanofiber-graft-polypeptide composite film. The surface-initiated graft atom transfer radical polymerization was conducted from a chitin macroinitiator film derived from the chitin nanofiber film.

Surface-Initiated Graft Atom Transfer Radical Polymerization of Methyl Methacrylate from Chitin Nanofiber Macroinitiator under Dispersion Conditions

Surface-initiated graft atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) from self-assembled chitin nanofibers (CNFs) was performed under dispersion conditions. Self-assembled CNFs were initially prepared by regeneration from a chitin ion gel with 1-allyl-3-methylimidazolium bromide using methanol; the product was then converted into the chitin nanofiber macroinitiator by reaction with α-bromoisobutyryl bromide in a dispersion containing N,N-dimethylformamide. Surface-initiated graft ATRP of MMA from the initiating sites on the CNFs was subsequently carried out under dispersion conditions, followed by filtration to obtain the CNF-graft-polyMMA film. Analysis of the product confirmed the occurrence of the graft ATRP on the surface of the CNFs.

Functionalization of lignin through ATRP grafting of poly(2-dimethylaminoethyl methacrylate) for gene delivery

The biomass kraft lignin was modified into lignin-based macroinitiators (LnMI) through esterification of the alcohol and phenol functional groups on lignin backbone with 2-bromo-isobutyric bromide under mild condition. Then a series of cationic amphiphilic lignin-based graft copolymers were synthesized by atom transfer radical polymerization (ATRP) of 2-(dimethylamino)ethyl methacrylate (DMAEMA) starting from the lignin-based macroinitiators. These copolymers, denoted as LnPDMAEMA, had a hyperbranched structure with a hydrophobic backbone of lignin and multiple cationic hydrophilic arms of PDMAEMA. The LnPDMAEMA copolymers were characterized by 1H NMR and elemental analysis (EA), and studied in terms of their DNA binding capability, formation of nanoparticles with plasmid DNA (pDNA), cytotoxicity, and gene transfection in cultured cells. It was found that all the copolymers could efficiently compact pDNA into nanoparticles with sizes ranging from 100 to 200nm at N/P ratios of 5 or higher. The cytotoxicity of these copolymers depends greatly on the chain length of PDMAEMA arms, the longer the PAMAEMA chain the higher the cytotoxicity. Luciferase assay was used to study the in vitro gene transfection for the LnPDMAEMA copolymers in different cell lines. The gene transfection efficiency of these copolymers was dependent on the grafted PDMAEMA chain length and N/P ratio. Generally, the transfection efficiency decreased with the increase of PAMAEMA length at N/P ratio of 20 or higher. It is very interesting that one of the LnPDMAEMA copolymers with very short arm length (degree of average DMAEMA units=5.5) showed excellent in vitro transfection efficiency that was comparable or even higher than that of branched PEI (25K). These novel biomass-based LnPDMAEMA hyperbranched copolymers can be a promising nonviral gene vectors for future gene delivery application.

Enhancing membrane performance by blending ATRP grafted PMMA–TiO2 or PMMA–PSBMA–TiO2 in PVDF

To improve PVDF (polyvinylidine fluoride) membrane property, TiO2 nano-particles can be blended in casting solutions to form composite membranes. In this study, TiO2 nano-particles were modified by coupling with γ-aminopropyl triethoxy silane (KH550), then grafted with PMMA (Polymethyl methacrylate) or co-grafted with PMMA and more hydrophilic PSBMA (polysulfobetaine methacrylate) via ATRP (atom transfer radical polymerization). ATRP grafting time and weight ratio of KH550 to TiO2 were two main identified factors affecting TiO2 modification and membrane hydrophilicity, flux and antifouling properties. These were shown by Scanning electron microscopy (SEM) characterization, contact angles measurements and filtration tests with yeast suspensions. The grafted TiO2–PMMA nano particles formed after coupling at 3:1 weight ratio of KH550 to TiO2 and 5h grafting, once composited with PVDF, formed a membrane with higher flux (up to 50%), higher flux recovery rate (FRR, 93.5%) and lower irreversible fouling (5.37%) than PVDF membrane composited with unmodified TiO2. Blending TiO2 co-grafted with PMMA and zwitterionic polymer PSBMA resulted in even better antifouling membranes (even lower Rir<2% and even higher FRR 99%). When the molar ratio of MMA to SBMA was 2 to 1, the highest steady flux and the highest FRR were obtained.

Synthesis of well-defined responsive membranes with fixable solvent responsiveness

A versatile method is described to synthesize a new family of solvent-responsive membranes whose response states can be not only tunable but also fixable via ultraviolet (UV) irradiation induced crosslinking. The atom transfer radical polymerization (ATRP) initiator 2-bromoisobutyryl bromide was first immobilized on the poly(ethylene terephthalate) (PET) track-etched membrane followed by room-temperature ATRP grafting of poly(2-hydroxyethyl methacrylate) (PHEMA) and poly(2-hydroxyethyl methacrylate-co-2-(dimethylamino)ethyl methacrylate) (P(HEMA-co-DMAEMA)) respectively. The hydroxyl groups of PHEMA were further reacted with cinnamoyl chloride (a photosensitive monomer) to obtain photo-crosslinkable PET-g-PHEMA/CA membrane and PET-g-P(HEMA/CA-co-DMAEMA) membrane. The length of grafted polymer chains was controllable by varying the polymerization time. X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy in attenuated total reflection and thermogravimetric analysis were employed to characterize the resulting membranes. The various membrane surface morphologies resulting from different states of the grafted chains in water and dimethylformamide were characterized by scanning electron microscopy. It was demonstrated that the grafted P(HEMA/CA-co-DMAEMA) chains had more pronounced solvent responsivity than the grafted PHEMA/CA chains. The surface morphologies of the grafted membranes could be adjusted using different solvents and fixed by UV irradiation crosslinking. © 2014 Society of Chemical Industry

Preparation of an efficient nanofiltration membrane based on blending of polysulfone and polysulfone-g-butylacrylate prepared by ATRP

Polysulfone is one of the most common used polymers for preparation of nanofiltration membranes. These membranes are highly susceptible to fouling problems because of their surface hydrophobic nature. In this paper a new approach for modification of polysulfone to overcome the fouling problems was introduced. The modification was carried out via blending of polysulfone with a modified grafted polysulfone using atom transfer radical polymerization (ATRP) method. The modified grafted polysulfone was synthesized via ATRP grafting of n-butylacrylate from chloromethylated polysulfone. The graft copolymers were characterized by FT-IR, NMR, DSG and TGA techniques. Furthermore, surface morphology and performance of the corresponding membrane were studied in detail using SEM and pure water flux and salt rejection experiments, respectively. The results indicated that the prepared modified polysulfone membranes have high surface hydrophilicity and therefore better fouling resistance and very good water permeability.

Cellulose Functionalization via ATRP Grafting of Glycidyl Methacrylate for Cr(VI) Adsorption

AbstractCellulose was first grafted with glycidyl methacrylate (GMA) in an ionic liquid via atom transfer radical polymerization (ATRP) and then the introduced epoxy groups were reacted with ethanediamine (EDA) to obtain an amino adsorbent. The grafting copolymer and the obtained adsorbent were characterized by FTIR, 1H NMR, TEM and SEM. The results showed that the grafted copolymers had grafted polymer chains with well‐controlled molecular weight and polydispersity, the polymerization was a controlled system. The cellulose adsorbent had numerous micropores on the surface and showed high performance for Cr(VI) adsorption. The adsorption behavior was pH dependent and the sorption equilibrium was achieved within 2 h on the adsorbent.

Surface initiated atom transfer radical polymerization grafting of sodium styrene sulfonate from titanium and silicon substrates.

This study investigates the grafting of poly-sodium styrene sulfonate (pNaSS) from trichlorosilane/10-undecen-1-yl 2-bromo-2-methylpropionate functionalized Si and Ti substrates by atom transfer radical polymerization (ATRP). The composition, molecular structure, thickness, and topography of the grafted pNaSS films were characterized with x-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectrometry (ToF-SIMS), variable angle spectroscopic ellipsometry (VASE), and atomic force microscopy (AFM), respectively. XPS and ToF-SIMS results were consistent with the successful grafting of a thick and uniform pNaSS film on both substrates. VASE and AFM scratch tests showed the films were between 25 and 49 nm thick on Si, and between 13 and 35 nm thick on Ti. AFM determined root-mean-square roughness values were ∼2 nm on both Si and Ti substrates. Therefore, ATRP grafting is capable of producing relatively smooth, thick, and chemically homogeneous pNaSS films on Si and Ti substrates. These films will be used in subsequent studies to test the hypothesis that pNaSS-grafted Ti implants preferentially adsorb certain plasma proteins in an orientation and conformation that modulates the foreign body response and promotes formation of new bone.

Nano‐Structured Polymer‐Silica Composite Derived from a Marine Diatom via Deactivation Enhanced Atom Transfer Radical Polymerization Grafting

A diatom frustule is functionalized with an alkyl halide to allow the growth of a polymer from its surface via deactivation enhanced atom transfer radical polymerization. The diatom core is partially dissolved to form a more translational platform. This method can be used to create an array of nano-structured composites derived from the species-specific diatom architecture.

Controlling Crystallinity in Graft Ionomers, and Its Effect on Morphology, Water Sorption, and Proton Conductivity of Graft Ionomer Membranes

To gain insight into the role of crystallinity and morphology on proton transport through solid polymer electrolytes, we synthesized graft copolymers, poly(vinylidene difluoride-co-chlorotrifluoroethylene)-g-polystyrene [P(VDF-co-CTFE)-g-PS], consisting of a hydrophobic, fluorous backbone and styrenic graft chain of varied length (DPstyrene = 39, 62, and 79), by graft atom transfer radical polymerization (ATRP). The polystyrene graft chains were subsequently sulfonated to different degrees to provide three series of polymers with controlled ion exchange capacity (IEC). The crystallinity and morphology of solution-cast membranes were examined by XRD and TEM, respectively. The grafting of the parent side chain is found to hinder crystallization of the fluorous backbone and the impact of the degree of sulfonation of the side chain on the crystallinity of the polymer is dependent on the graft length: No impact is found for medium and long graft lengths, but for short graft length copolymers (PS39), the degree of crystallinity in the sulfonated membranes is twice that of the unsulfonated membrane. A phase-separated morphology consisting of 2–5 (±1) nm ion-rich domains is observed for all of the graft copolymers. These graft copolymers allow access to very high IEC membranes (>3 mmol/g), which are insoluble in water. The shorter graft length series, P(VDF-co-CTFE)-g-SPS39, swells less in the intermediate IEC range (<3.0 mmol/g) because of its higher degree of crystallinity and lower PS to VDF ratio, and provides membranes with exceptionally high proton conductivity. Two graft series possessing similar weight fraction of PS but different graft density were also examined in order to evaluate the effect of graft density. It was found that lower graft density copolymers possess higher crystallinity and more contiguous PVDF domains, which allow high IEC membranes to be prepared that swell to lower extents.

Aqueous-Based Initiator Attachment and ATRP Grafting of Polymer Brushes from Poly(methyl methacrylate) Substrates

Many polymers, such as PMMA, are very susceptible to swelling or dissolution by organic solvents. Growing covalently attached polymer brushes from these surfaces by atom-transfer radical polymerization (ATRP) is challenging because of the typical requirement of organic solvent for initiator immobilization. We report an unprecedented, aqueous-based route to graft poly(N-isopropylacrylamide), PNIPAAm, from poly(methyl methacrylate), PMMA, surfaces by ATRP, wherein the underlying PMMA is unaffected. Successful attachment of the ATRP initiator, N-hydroxysuccinimidyl-2-bromo-2-methylpropionate, on amine-bearing PMMA surfaces was confirmed by XPS. From this surface-immobilized initiator, thermoresponsive PNIPAAm brushes were grown by aqueous ATRP to yield optically transparent PNIPAAm-grafted PMMA surfaces. This procedure is valuable, as it can be applied for the aqueous-based covalent attachment of ATRP initiator on any amine-functionalized surface, with subsequent polymerization of a variety of monomers.

Functional polymer brushes via surface-initiated atom transfer radical graft polymerization for combating marine biofouling

Dense and uniform polymer brush coatings were developed to combat marine biofouling. Nonionic hydrophilic, nonionic hydrophobic, cationic, anionic and zwitterionic polymer brush coatings were synthesized via surface-initiated atom transfer radical polymerization (SI-ATRP) of 2-hydroxyethyl methacrylate, 2,3,4,5,6-pentafluorostyrene, 2-(methacryloyloxy)ethyl trimethylammonium chloride, 4-styrenesulfonic acid sodium and N,N′-dimethyl-(methylmethacryloyl ethyl) ammonium propanesulfonate, respectively. The functionalized surfaces had different efficacies in preventing adsorption of bovine serum albumin (BSA), adhesion of the Gram-negative bacterium Pseudomonas sp. NCIMB 2021 and the Gram-positive Staphylococcus aureus, and settlement of cyprids of the barnacle Amphibalanus amphitrite (=Balanus amphitrite). The nonionic hydrophilic, anionic and zwitterionic polymer brushes resisted BSA adsorption during a 2 h exposure period. The nonionic hydrophilic, cationic and zwitterionic brushes exhibited resistance to bacterial fouling (24 h exposure) and cyprid settlement (24 and 48 h incubation). The hydrophobic brushes moderately reduced protein adsorption, and bacteria and cyprid settlement. The anionic brushes were least effective in preventing attachment of bacteria and barnacle cyprids. Thus, the best approach to combat biofouling involves a combination of nonionic hydrophilic and zwitterionic polymer brush coatings on material surfaces.

Nitroxide mediated and atom transfer radical graft polymerization of atactic polymers onto syndiotactic polystyrene

'Living' radical graft polymerization was employed to prepare graft copolymers with nitroxide-mediated arylated syndiotactic polystyrene as the backbone and polystyrene (PS), poly(p-methylstyrene) (PMS) and poly(methylmethacrylate) (PMMA) as branches. A two-stage process has been developed to synthesize the macroinitiator. First, syndiotactic polystyrene (sPS) was modified by the Friedel-Crafts reaction to introduce chlorine; second, the chlorine groups were converted to nitroxide mediated groups by coupling with 1-hydroxy-2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO-OH). The resulting macroinitiator (sPS-TEMPO) for 'living' free radical polymerization was then heated in the presence of styrene and p-methylstyrene to form graft and block copolymers. We used the obtained copolymer and N-bromosuccinimide as brominating agent to achieve polymers with bromine groups. This brominated copolymer was used as a macroinitiator for polymerizing methyl methacrylate in the presence of the CuBr/bpy catalyst system. The formation of the graft and block copolymers was confirmed by DSC, ¹H NMR and FTIR spectroscopy. This approach using macroinitiators is an effective method for the preparation of new materials.

Cellulose acetate graft copolymers with nano-structured architectures: Synthesis and characterization

Cellulose acetate is a very good film-forming polymer with major applications in cigarette filters, photographic films, cosmetics and pharmaceutics formulations and membrane separation processes. Nevertheless, its rigidity and relative hydrophobic character can be limiting drawbacks for some applications. In this work, new cellulose acetate materials with highly flexible and hydrophilic grafts were obtained with different hydrophilic/hydrophobic balances. Cellulose acetate was grafted with methyl diethylene glycol methacrylate (MDEGMA) from brominated macroinitiators by atom transfer radical polymerization (ATRP) in two steps. The first step consisted of introducing ATRP initiator groups on cellulose acetate by reacting hydroxyl side groups with 2-bromoisobutyryl bromide. A preliminary study was then carried out to determine the experimental conditions for the controlled ATRP of MDEGMA homopolymerization in a solvent (cyclopentanone) compatible with cellulose acetate grafting. In these conditions, the MDEGMA homopolymerization followed Hanns Fischer’s kinetics model accounting for the radical persistent effect. The ATRP grafting was then investigated for two cellulose acetate macroinitiators differing in the number of their ATRP initiator groups. Two families of graft copolymers with nano-structured architectures were obtained. The first family corresponded to copolymers with a high number of short grafts. The copolymers of the second family had almost the same graft weight fractions but a small number of long grafts. The morphology of the graft copolymers was then investigated by synchrotron X-ray scattering. The most informative results showed that the phase segregation depended upon the number and length of the poly(MDEGMA) grafts. The copolymer with 44 wt.% of long grafts showed a segregated morphology of nano-domains with sharp interfaces and a radius of gyration of 11.5 nm (from Guinier’s law). These cellulose acetate copolymers eventually led to strong films with potential applications in membrane separations.

Synthesis of photo- and pH-responsive composite nanoparticles using a two-step controlled radical polymerization method

We present a versatile synthetic method for photo- and pH-sensitive composite nanoparticles using a combined use of reversible addition-fragmentation chain transfer (RAFT) and atom transfer radical polymerization (ATRP). Crosslinked nanoparticles of a random copolymer composed of methyl methacrylate (MMA), 4-vinylbenzyl chloride (VBC) and divinylbenzene (DVB) were first synthesized using RAFT miniemulsion polymerization in aqueous solution. This was followed by solvent exchange through extraction and dialysis that allowed the nanoparticles to be transferred to and highly swollen in an organic solvent (anisole or THF). By dissolving a monomer of a stimuli-responsive polymer in the solution, subsequent ATRP grafting polymerization could be initiated by halide groups on the swollen nanoparticle, resulting in larger composite nanoparticles. Photosensitive poly(1-pyrenylmethyl methacrylate) (PPyMA) and pH-sensitive poly(dimethylaminoethyl methacrylate) (PDMAEMA) were incorporated in the composite nanoparticles, and their photo- and pH-responsive behaviors were investigated. With this method, monomers soluble in organic solvents can be used in conjunction with emulsion polymerization in aqueous solution to design functional composite nanoparticles.