Grafting of Polystyrene from Narrow Disperse Polymer Particles by Surface-Initiated Atom Transfer Radical Polymerization

Zheng, Guodong; Stöver, Harald D. H.

doi:10.1021/ma0121464

Cited by 120 publications

(102 citation statements)

References 38 publications

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“…9 The microspheres also have a thin surface layer consisting of lightly crosslinked and swellable poly(DVB). 10 Both DVB containing 55% (DVB55) and 80% (DVB80) can be employed for the synthesis of microspheres; DVB55 results in microspheres with a slightly thicker, lightly crosslinked surface layer than DVB80 because of the lower content of DVB in DVB55.…”

Section: Introductionmentioning

confidence: 99%

“…10,14,15 The novel approach employs ultraviolet (UV) irradiation to initiate the polymeri-zation (k ¼ 365 nm) at ambient temperatures. The critical advantage of the present UV based approach is the fact that the particle formation process is performed at ambient temperature (25 8C T 40 8C), thus making it a highly valuable tool for the use in controlled drug release technology (e.g., the encapsulation of proteins during particle synthesis) which typically requires low temperatures (T < 37 8C) to avoid protein/ biomolecule denaturation.…”

Section: Introductionmentioning

confidence: 99%

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Ambient temperature synthesis of well‐defined microspheres via precipitation polymerization initiated by UV‐irradiation

Joso

Pan

Stenzel

et al. 2007

J. Polym. Sci. A Polym. Chem.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Ambient temperature synthesis of well‐defined microspheres via precipitation polymerization initiated by UV‐irradiation

Joso

Pan

Stenzel

et al. 2007

J. Polym. Sci. A Polym. Chem.

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“…Several authors have reported grafting using surface-initiated living radical polymerization (LRP) on a variety of surfaces, e.g., inorganic solid surfaces [29][30][31] and organic polymer surfaces. [32][33][34] Most of these studies are focused on the control of molecular weight of the grafted polymer, while only limited attention has been given the quantification of grafting densities. However, Fukuda and coworkers [35,36] concentrated on the quantification of grafting densities as well as attempts to achieve high grafting densities on solid substrates.…”

mentioning

confidence: 99%

Quantification of Grafting Densities Achieved via Modular “Grafting‐to” Approaches onto Divinylbenzene Microspheres

Nebhani

Schmiedl

Barner

et al. 2010

Adv Funct Materials

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The surface modification of divinylbenzene (DVB)‐based microspheres is performed via a combination of reversible addition fragmentation chain transfer (RAFT) polymerization and rapid hetero‐Diels–Alder (HDA) chemistry with the aim of quantifying the grafting densities achieved using this “grafting‐to” method. Two variants of the RAFT‐HDA concept are employed to achieve the functionalization of the microspheres. In the first approach, the microspheres are functionalized with a highly reactive diene, i.e., cyclopentadiene, and are subsequently reacted with polystyrene chains (number‐averaged molecular weight, Mn = 4200 g mol−1; polydispersity index, PDI = 1.12.) that carry a thiocarbonyl moiety functioning as a dienophile. The functionalization of the microspheres is achieved rapidly under ambient conditions, without the aid of an external catalyst. The surface grafting densities obtained are close to 1.2 × 1020 chains per gram of microspheres. In the second approach, the functionalization proceeds via the double bonds inherently available on the microspheres, which are reacted with poly(isobornyl acrylate) chains carrying a highly dienophilic thiocarbonyl functionality; two molecular weights (Mn = 6000 g mol−1, PDI = 1.25; Mn = 26 000 g mol−1, PDI = 1.26) are used. Due to the less reactive nature of the dienes in the second approach, functionalization is carried out at elevated temperatures (T = 60 °C) yet in the absence of a catalyst. In this case the surface grafting density is close to 7 chains nm−2 for Mn = 6000 g mol−1 and 4 chains nm−2 for Mn = 26 000 g mol−1, or 2.82 × 1019 and 1.38 × 1019 chains g−1, respectively. The characterization of the microspheres at various functionalization stages is performed via elemental analysis for the quantification of the grafting densities and attenuated total reflectance (ATR) IR spectroscopy as well as confocal microscopy for the analysis of the surface chemistry.

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“…Two steps are typically needed to obtain core-shell particles such as in grafting by living radical polymerization techniques, two-stage precipitation polymerization, and stepwise saponification of suspension and dispersion polymerization. [22][23][24][25][26][27][28][29] Of particular interest is the surface modification of spheres with poly(ethylene glycol) (PEG) to generate surfaces that are biocompatible, and resistant to attacks by macrophages and other blood components in the human body. Furthermore, PEGylated spheres are observed to have a decreased protein adsorption.…”

Section: Full Papermentioning

confidence: 99%

One Pot Synthesis of Surface PEGylated Core–Shell Microparticles by Suspension Polymerization with Surface Enrichment of Biotin/Avidin Conjugation

Ting¹,

Nguyen²,

Stenzel³

2009

Macromolecular Bioscience

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Core-shell microparticles that consist of poly(vinyl neodecanoate) (VND) crosslinked with poly(ethylene glycol dimethacrylate) (EGDMA) as the core and poly(ethylene glycol methacrylate) (PEGMA) (Mn = 360 or Mn = 526 g . mol(-1)) as the shell have been synthesized using suspension polymerization by a conventional free radical polymerization process. Interfacial tension and stability tests show that PEGMA acts as an amphiphilic macromonomer and is located on the oil/water interface of the suspension system, thus forming an outer layer during the polymerization. Kinetic studies of the monomers' conversion of VND, EGDMA, and PEGMA have been carried out using (1)H NMR spectroscopy. EGDMA and PEGMA were found to have faster reaction rates compared to VND. Moreover, scanning electron microscopy showed that the polymerization of these particles starts from the shell and finishes towards the core. Consequently, the resulting microsphere is found to have a multi-layer structure. Biotin was covalently bound to the surface by the PEGMA hydroxy groups. Conjugation of biotin with streptavidin PE (phycoerythrin) was subsequently carried out. Confocal microscopy was used to confirm the presence of fluorescing streptavidin. The amount of avidin conjugated to the microspheres was calculated by the release of a 2-(4-hydroxyphenylazo)benzoic acid/avidin complex using UV/vis spectroscopy. One avidin molecule was found to occupy 7 nm(2) on the surface of the microspheres.

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Grafting of Polystyrene from Narrow Disperse Polymer Particles by Surface-Initiated Atom Transfer Radical Polymerization

Cited by 120 publications

References 38 publications

Ambient temperature synthesis of well‐defined microspheres via precipitation polymerization initiated by UV‐irradiation

Ambient temperature synthesis of well‐defined microspheres via precipitation polymerization initiated by UV‐irradiation

Quantification of Grafting Densities Achieved via Modular “Grafting‐to” Approaches onto Divinylbenzene Microspheres

One Pot Synthesis of Surface PEGylated Core–Shell Microparticles by Suspension Polymerization with Surface Enrichment of Biotin/Avidin Conjugation

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