Electrocatalytic Depolymerization of Self-Immolative Poly(Dithiothreitol) Derivatives.

Area of Science:

• Polymer Chemistry
• Electrochemistry
• Materials Science

Background:

• Self-immolative polymers (SIPs) offer controlled degradation pathways.
• Poly(dithiothreitol) (pDTT) is a class of SIPs featuring disulfide bonds in their backbone and end-caps.
• Initiating depolymerization of pDTT typically requires specific triggers.

Purpose of the Study:

• To investigate the use of electrogenerated anthraquinone radical anion (AQ•^-) as a trigger for pDTT depolymerization.
• To determine the efficiency and mechanism of AQ•^--mediated depolymerization.
• To assess the general applicability of this electrochemical method for disulfide polymers.

Main Methods:

• Synthesis of pDTT derivatives with varying end-caps (thiohexyl, AQ, methyl).
• Electrochemical generation of anthraquinone radical anion (AQ•^-).
• Monitoring depolymerization kinetics using electrochemical and analytical techniques.

Main Results:

• AQ•^- effectively catalyzed the rapid depolymerization of all studied pDTT derivatives.
• Complete depolymerization of pDTT was achieved with as little as 0.2 electrons per polymer chain.
• A mechanism involving electron transfer to disulfide bonds, generating thiyl radicals, was proposed.
• Thiyl radicals propagate depolymerization via a chain reaction.

Conclusions:

• Electrochemical triggering using AQ•^- is a highly efficient method for initiating pDTT depolymerization.
• This approach demonstrates a general strategy for the catalytic degradation of disulfide-containing polymers.
• The findings open avenues for controlled polymer degradation using electrochemistry.