Controlled Radical Polymerization of Styrene with Phosphoryl- and (Thiophosphoryl)dithioformates as RAFT Agents

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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“…Materials: BEPTF and PSDTF were synthesized according to the literature [28,42]. Styrene (Aldrich), divinyl benzene (tech.…”

Section: Methodsmentioning

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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“…For this purpose, both activating substituent Z and leaving group R of the CTA Z-C( S)-S-R should be selected properly. [5][6][7][8][9][10][11] Communication: The capability of three chain-transfer agents, O-alkyl-S-(1-ethoxycarbonyl)ethyl xanthates (CH 3 -CHCO 2 C 2 H 5 )S(C S)OZ 0 , to control the free-radical polymerization of styrene and ethyl acrylate by the MADIX process was examined. The reactivity of the xanthates varied according to the following trend: Z 0 CH 2 CH 3 < CH 2 CF 3 < CH[P(O)(OEt) 2 ]CF 3 .…”

Section: Introductionmentioning

confidence: 99%

Xanthates as Chain‐Transfer Agents in Controlled Radical Polymerization (MADIX): Structural Effect of the O‐Alkyl Group

Destarac

Bzducha²,

Taton

et al. 2002

Macromol. Rapid Commun.

190

214

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The capability of three chain‐transfer agents, O‐alkyl‐S‐(1‐ethoxycarbonyl)ethyl xanthates (CH3CHCO2C2H5)S(CS)OZ′, to control the free‐radical polymerization of styrene and ethyl acrylate by the MADIX process was examined. The reactivity of the xanthates varied according to the following trend: Z′  CH2CH3 < CH2CF3 < CH[P(O)(OEt)2]CF3. This change in reactivity allowed a lowering of the polydispersity index from 2.0 for Z′  CH2CH3 to 1.15 for Z′  CH[P(O)(OEt)2]CF3 in the case of the polymerization of styrene. Evolution of Mw/Mn with conversion during the polymerization of ethyl acrylate in the presence of xanthates X1, X2 and X3. Reaction conditions: [EA]0 = 4.6 M, [X]0 = 5.75 × 10−2 M, [AIBN]0 = 1.72 × 10−3 M ; T = 80 °C ; solvent: toluene.magnified imageEvolution of Mw/Mn with conversion during the polymerization of ethyl acrylate in the presence of xanthates X1, X2 and X3. Reaction conditions: [EA]0 = 4.6 M, [X]0 = 5.75 × 10−2 M, [AIBN]0 = 1.72 × 10−3 M ; T = 80 °C ; solvent: toluene.

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“…[23,24] Experimental Part Materials Benzyl (diethoxyphosphoryl) dithioformate (BEPTF) (1) was synthesized according to the literature. [25] DVB (tech. 80%, DVB80, Aldrich) was passed through a column of basic alumina (Aldrich) and stored at 19 8C prior to usage.…”

Section: Introductionmentioning

confidence: 99%

Efficient Surface Modification of Divinylbenzene Microspheres via a Combination of RAFT and Hetero Diels‐Alder Chemistry

Nebhani

Sinnwell

Inglis

et al. 2008

Macromol. Rapid Commun.

105

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A combination of reversible addition fragmentation chain transfer (RAFT) polymerization and hetero Diels‐Alder (HDA) chemistry has been utilized to successfully generate functional core‐shell microspheres. Initially, precipitation polymerization in conjunction with the RAFT technique has been employed to synthesize divinylbenzene (DVB) microspheres with surface expressed RAFT groups. Subsequently, HDA cycloaddition has been performed under mild reaction conditions (50 °C, 24 h) with a diene‐functionalized poly(ε‐caprolactone) (PCL). While the successful grafting is immediately evident by optical inspection of the microspheres (color change from purple to white), X‐ray photoelectron spectroscopy (XPS), and attenuated total reflectance spectroscopy (ATR) were additionally employed to characterize the chemical composition and surface functionalization of the microspheres. Further, confocal microscopy was used to confirm the presence of grafted PCL chains after labeling them with rhodamine B.magnified image

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Controlled Radical Polymerization of Styrene with Phosphoryl- and (Thiophosphoryl)dithioformates as RAFT Agents

Cited by 62 publications

References 24 publications

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

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

Xanthates as Chain‐Transfer Agents in Controlled Radical Polymerization (MADIX): Structural Effect of the O‐Alkyl Group

Efficient Surface Modification of Divinylbenzene Microspheres via a Combination of RAFT and Hetero Diels‐Alder Chemistry

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