Low-voltage activated adhesives have recently been invented, aka ‘voltaglue’, leading to electrochemically mediated adhesive curing (electrocuring)[1]. Consisting of new and established adhesive crosslinking groups, formulations incorporate dendrimers that have a preference of intermolecular crosslinking while allowing flexible incorporation of functional groups. Upon voltage activation, specific functional groups are activated and covalently bond to a variety of surfaces, but this is highly dependent on bulk conductivity.

To tailor the adhesive properties and adhesion strength, internal additives have been explored towards increasing conductivity and ultimately the ‘voltaglue’ crosslinking efficiency. Flexible electrocuring is sought to achieve a range of material properties, from viscous gels to hard set matrices. Ferrocene, a well-known redox active compound with reversible one-electron redox behaviour[2], is often incorporated in polymers/dendrimers due to its reversible nature and conductive aspects [3]. By integrating the ferrocene internal additive into dendrimer formulations combined with the electrically activated crosslinking additives we are able to mediate the electrocuring properties to a limited degree.

In this work we present the synthesis of PAMAM-g-ferrocene-g-diazirine, an electrocuring adhesive that is able to adhere to a range of substrates, with adhesive strengths at the kPa scale. Real time electrorheology measurements chemistry evaluate the range of material properties available and demonstrate the synergistic performance ferrocene internal additives impart on the ‘voltaglue’ adhesives.

 

 

References

 

[1] J. Ping, F. Gao, J.L. Chen, R.D. Webster, T.W.J. Steele, Adhesive curing through low-voltage activation, Nature Communications 6 (2015).

[2] M.E. N.P.R.A. Silva, A.J.L. Pombeiro, J.J.R. Fraústo da Silva, R. Herrmann, N. Deus, R. E.Bozak, Redox potential and substituent effects in ferrocene derivatives: II, Journal of Organometallic Chemistry 480 (1994).

[3] R. Gracia, D. Mecerreyes, Polymers with redox properties: materials for batteries, biosensors and more, Polymer Chemistry 4 (2013).

[4] C.M. Elson, M.T.H. Liu, C. Mailer, Electron-spin-resonance studies of diazirine anion radicals, Journal of the Chemical Society, Chemical Communications 7 (1986).