Self‐Immolative Polycarbamates From 4‐Hydroxybenzaldehyde, Vanillin, and Syringaldehyde

ABSTRACT There is currently substantial interest in degradable polymers that can be prepared from renewable, bio‐based monomers. Lignin in particular is an attractive source for aromatic building blocks, as it is a waste product from the pulping process, and research is underway to improve processes to isolate molecules such as 4‐hydroxybenzaldehyde, vanillin, and syringaldehyde from lignin. Among the classes of degradable polymers, self‐immolative polymers (SIPs) can offer controlled, end‐to‐end depolymerization, making them attractive for a range of applications. Described here is the incorporation of 4‐hydroxybenzyl alcohol, vanillyl alcohol, and syringyl alcohol into SIPs. After initial attempts to synthesize polycarbonates, our efforts shifted to polycarbamates containing N,N ′‐dimethylethylenediamine spacers. The steric hindrance imparted by the methoxy groups on vanillyl alcohol and syringyl alcohol decreased the reactivity of the adjacent phenol and corresponding activated derivatives in the synthesis of the monomers, but after incorporation of the diamine spacer, the polycarbamate SIPs could be prepared with similar degrees of polymerization. The methoxy substituents slowed the depolymerization of the vanillyl alcohol and syringyl alcohol‐derived SIPs compared to the SIP derived from 4‐hydroxybenzyl alcohol. Meanwhile, the syringyl alcohol‐derived polymer exhibited decreased background degradation in the absence of end‐cap cleavage.