Synthesis and degradation behavior of self-immolative polymer derived from vanillyl alcohol as a biodegradable aromatic unit

We synthesized a bio-based self-immolative polymer (SIP) from vanillyl alcohol (VA), which can be obtained from lignin. The VA-based SIP (VA-SIP) is a polycarbamate comprising alternating units of VA and N,N '-dimethylethylenediamine (DMEDA), and a tert-butyldicarbonate (Boc) end-capping group that triggers a cascade of self-degradation in the main-chain. The molecular weight of the VA-SIP reached Mn = 1.5-8.2 x 103 Da. After removing the Boc group under acidic conditions, we monitored the degradation behavior of the VA-SIP by in situ nuclear magnetic resonance (NMR) analysis. The VA-SIP spontaneously degraded, indicating successful selfcascade degradation of the main-chain, and ultimately yielded VA. The self-cascade degradation rate of the VA-SIP was dependent on its molecular weight and the temperature. At 37 degrees C, the degree of degradation of a representative VA-SIP (Mn = 2.5 x 103 Da) was 68 % after 55 days. Biochemical oxygen demand (BOD) tests revealed that VA is readily biodegradable in freshwater. VA-SIP has potential as a bio-based and biodegradable plastic. Furthermore, it can be induced to undergo main-chain self-degradation, and subsequent biodegradation of the monomer, by environmental stimuli.