Gold Nanoparticles Protected with Thiol-Derivatized Amphiphilic Poly( -caprolactone)-b-poly(acrylic acid)

Irakli Javakhishvili, Søren Hvilsted

Research output: Chapter in Book/Report/Conference proceedingArticle in proceedingsResearchpeer-review

Abstract

Amphiphilic poly(c-caprolactone)-b-poly(acrylic acid) (HS-PCL-b-PAA) bearing thiol functionality at the PCL terminal has been synthesized by a combination of ring-opening polymerization (ROP) of c-caprolactone (c-CL), esterification of hydroxy chain end with protected mercaptoacetic acid, subsequent chain-extension by atom transfer radical polymerization (ATRP) of tert-butyl acrylate (tBA), and final deprotection steps. ROP of c-CL initiated by 2-hydroxyethyl 2-bromoisobutyrate, and catalysed by tin octoate afforded Br-PCL-OH with the degree of polymerization of 30 and narrow molecular weight distribution (1.09). The hydroxy chain end of Br-PCL-OR was modified by reacting with a-(2,4-dinitrophenylthio)acetic acid or a-(4methoxytritylthio) acetic acid resulting in heterotelechelic PCL incorporating protected thiol and bromoester functionalities. It was then employed as macroinitiator in NiBr2(PPh3)2 catalysed ATRP of tBA. ATRP of tBA provided diblock copolymers with low polydispersity index (1.17-1.39) while preserving the protected thiol function. Sequential or simultaneous removal of 2,4-dinitrophenyl or 4-methoxytrityl and tert-butyl ester groups resulted in HS-PCL-b-PAA. The PCL backbone remained intact after mild deprotection protocols. Thus, reversible masking of thiol functionality allows facile fusion of the controlled polymerization techniques employing dual initiator strategy, and furnishes RS-PCL-bPAA with well-defined chain architecture which has been assessed by size exclusion chromatography (SEC), nuclear magnetic resonance eR NMR) and infrared (FT IR) spectroscopy. The capacity of the resulting block copolymer in preparation of monolayer-protected gold nanoparticles has been examined by reduction of a gold salt in the presence of this macroligand under thiol-deficient conditions. As a result stable, aggregation-free nanopaticles with moderate dispersity as estimated from UV-visible spectroscopy and transmission electron microscopy (TEM) data were obtained.
Original languageEnglish
Title of host publicationNPD Nordic Polymer Days 2008
Number of pages58
Publication date2008
Publication statusPublished - 2008
EventNordic Polymer Days 2008 - Stockholm, Sweden
Duration: 11 Jun 200813 Jun 2008

Conference

ConferenceNordic Polymer Days 2008
CountrySweden
CityStockholm
Period11/06/200813/06/2008

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