Well-defined redox-active polymers and block copolymers prepared by living ring-opening metathesis polymerization

Abstract

REPORT DOCUMENTATION PAGEReproduction in whole or in part is permitted for any purpose of the United States Government.This document has been approved for public release and sale; its distribution is unlimited. it is not oxidized at potentials up to 1.0 V. An analogous initiator containing a ferrocenylmethylidene ligand (ib) can be synthesized by treating la with vinylferrocene. Redoxactive derivatives of norbornene, containing ferrocene (2) or phenothiazine (3) were prepared and polymerized by la or lb to give living block copolymers containing the ring-opened norbornene derivatives. The living polymer was cleaved from the metal in a Wittig-like reaction with pivaldehyde, trimethylsilylbenzaldehyde, or octamethylferrocenecarboxaldehyde. Polydispersities for the longer block copolymers containing up to -80 monomer units was found to be as low as 1.05 by GPC. In one case the polydispersity of a homopolymer made from the ferrocenecontaining monomer was determined by FD-Mass Spectroscopy to be 1.06. DSC studies suggest that microphase formation occurs in the block copolymers, even in the case of relatively low 4 molecular weight materials. Solution voltammetric studies of homo and block copolymers showed that the redox centers were electrochemically independent, and that all centers exchanged electrons with the electrode. Neutral polymers became insoluble upon oxidation to a polycation, yielding an adsorbed polymer layer on the electrode that could then be cathodically stripped. This oxidative deposition process depended on the electrolyte and the polymer molecular weight, but also could be controlled by the size of a non-electroactive block ir the block copolymers. Problems resulting from precipitation of the redox polymers could be circumvented by employing normal pulse voltammetry. Polymers containing redox-active centers in both end groups, as well as in the polymer chain itself, have been prepared and shown in electrochemical studies to undergo the expected initiation, propagation, and termination reactions.

Cobaltocenium‐Functionalized Poly(propylene imine) Dendrimers: Redox and Electromicrogravimetric Studies and AFM Imaging

“…It is also clear from Table 1 that the values of the diffusion coefficients obtained by NPV are not only about an order of magnitude larger than those obtained by CV, but also unrealistically high in some cases such as 4. Although the use of NPV has been previously recommended for the measurement of diffusion coefficients of materials that adsorb, [21] in our case the very nature of the experiment gives rise to the anomalous results alluded to above. This arises, at least in part, because in NPV the time delay between pulses is too short to allow for material that has adsorbed on the forward pulse to desorb.…”

Synthesis and electrochemical study of some novel alkynylferrocene derivatives

“…For example, ferrocenyl and multiferrocenyl systems have been used as mediators in amperometric biosensors [2][3] as redox sensors for molecular recognition [4][5][6][7][8] , as building blocks in polymers [9][10][11][12] or as coatings to modify electrode surfaces [13][14][15][16] . Electrochemical techniques have been particularly investigated for determining the concentration of biologically and clinically important compounds.…”

Organometallic Polymers of the Transition Metals

“…[152,153] Norbornene monomers functionalized with ferrocene groups or catalysts containing ferrocenyl moieties in their structures were utilized to prepare redoxactive organoiron polymers. Scheme 41 shows the ROMP of organometallic monomer 129 to produce the ferrocenesubstituted polymer 130.…”

“…Scheme 41 shows the ROMP of organometallic monomer 129 to produce the ferrocenesubstituted polymer 130. [152] Ferrocenophanes have also been subjected to ROMP to produce high-molecular-weight organometallic polymers. [154][155][156] The ROMP of ferrocenophanes was reported in 1995 by Grubbs, Lewis and coworkers.…”