TITLE

ATRP grafting of oligo(ethylene glycol) methacrylates from gold surface � Effect of monomer size on grafted chain and EO unit densities

AUTHOR(S)
Zhilin Jin; Brash, John L.; Shiping Zhu
PUB. DATE
May 2010
SOURCE
Canadian Journal of Chemistry;May2010, Vol. 88 Issue 5, p411
SOURCE TYPE
Academic Journal
DOC. TYPE
Article
ABSTRACT
Oligo(ethylene glycol) methacrylate (OEGMA) was grafted from Au surface via surface-initiated atom-transfer radical polymerization (s-ATRP). The initiator density was adjusted by the mole fractions of surface-attachable ATRP initiator and diluting agent. Three OEGMA monomers of Mr 300, 475, and 1100 were used. The Au surfaces before and after modification were characterized by water contact angle and ellipsometry. The effect of monomer Mr and initiator density on surface chain density and EO unit density was investigated. It was found that at low initiator density (mole fraction of initiator of 2%�5%), poly(OEGMA) grafts had comparable surface chain density independent of OEGMA Mr. However, at high initiator density (mole fraction of initiator�>10%), poly(OEGMA)1100 had obviously lower chain densities than poly(OEGMA)300 and poly(OEGMA)475, which could be attributed to the size difference of the monomers. The short chain length and low surface chain density of poly(OEGMA)1100 resulted in its relatively low surface EO unit density. On a greff� du m�thacrylate d�oligo(�thyl�neglycol) (MAOEG) sur une surface d�or par le biais d�une polym�risation radicalaire par transfert d�atome initi� par la surface (PRTA-s). La densit� de l�initiateur a �t� ajust�e par les fractions molaires de l�initiateur de la PRTA qui peuvent �tre attach�es � la surface et l�agent diluant. On a utilis� trois MAOEG de Mr 300, 475 et 1100. On a caract�ris� les surfaces d�or avant et apr�s modification par l�angle de contact de l�eau et par ellipsom�trie. On a �tudi� l�effet du poids mol�culaire du monom�re et la densit� de l�initiateur sur la densit� de la cha�ne en surface et sur la densit� de l�unit� d�oligo�thyl�neglycol. On a trouv� que pour des densit�s d�initiateur faibles (fraction molaire d�initiateur allant de 2 % � 5 %), la densit� de cha�ne en surface des greffes est ind�pendante du Mr du MAOEG. Toutefois, � des densit�s d�initiateur plus �lev�es (fraction molaire d�initiateur sup�rieure � 10 %), les densit�s de cha�ne du poly(MAOEG)1100 sont �videmment plus faibles que celles des poly(MAOEG)300 et poly(MAOEG)475 et cette situation peut �tre attribu�e � une diff�rence dans la taille des monom�res. La courte longueur de la cha�ne et la faible densit� de la cha�ne de surface du poly(MAOEG)1100 r�sultent de la densit� relativement faible de l�unit� d�oligo�thyl�neglycol.
ACCESSION #
49733529

 

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