TWO-DIMENSIONAL ARRAY OF POLY(METHACRYLIC ACID) BRUSHES ON GOLD SUBSTRATES - INTERACTION WITH FERROCENE-TERMINATED POLY(OXYETHYLENE)S

摘要

Polymeric amphiphiles (1(n)), consisting of a poly(methacrylic acid) (PMAA) segment (segment length, n = 35 and 63) and two long alkyl chains whose ends are modified with disulfide, form self-assembled monolayers on gold electrodes. The lateral molecular distribution within the monolayers is successfully controlled by varying the conformational size of the PMAA segments during assembling. Ferrocene-terminated poly(oxyethylene)s (2(m)), having various chain lengths (m = 10-120) are prepared and used as guest polymers. Host-guest interactions of 2(m) and the 1(n) monolayer-covered gold electrodes can be monitored electrochemically by means of electron transfer of the ferrocene moiety. The amount of adsorbed 2(m) gives a maximum when the chain length of guest 2(m) (m) matches that of host 1(n) monolayer (n). When the lateral molecular distribution in the monolayer brushes is controlled to be most favorable for the guest polymers, a 1:1 host-guest polymer complexation can be accomplished. FTIR spectroscopic data suggest that such complexation results from multiple hydrogen bonding between the COOH groups and the ether oxygen atoms. [References: 30]