To obtain thiol-ene polymers from M2 and M3 with stimuli-responsive depolymerization capabilities, post-polymerization thiolene modification was performed (Scheme 2). A fluoride ion-sensitive tert-butyldimethylsilyl (TBS) ether end-cap was efficiently incorporated into both Vi-P2b and Vi-P3, affording TBS-P2 and TBS-P3, respectively. In addition, thiol-sensitive thioacetate (TA), reduction-sensitive 4-nitrobenzyl thioether (NB), and non-responsive control benzyl thioether (Bn) end-caps were also introduced onto Vi-P2b to produce TA-P2, NB-P2, and Bn-P2 respectively, suggesting the generalizability of this post-polymerization functionalization method. 1 H NMR spectroscopy and SEC analyses confirmed the resulting polymer structures (Figures ). We next sought to evaluate the triggered depolymerization profiles of the SIPs. SEC was first employed to probe the degradation of TBS-P2 in DMF upon treatment with tetra-n-butylammonium fluoride (TBAF) in the presence of DBU and NMA. A progressive shift from high to low molar mass was observed, and the Mn decreased to ~1.4 kg/mol after 48 h from the initial ~6.2 kg/mol (Figure ). The controlled degradation of TBS-P2 upon exposure to TBAF was also supported by 1 H NMR analysis in DMF-d7 (Figure ). Moreover, the proposed degradation product was clearly observed by ESI-MS analysis, showing a peak corresponding to NMA-trapped quinone methide (Figure ). To further confirm the effect of spacer length between sulfur and the carbonyl moieties on the depolymerization, TBS-P2 was dissolved in a mixture of DMSO-d6 and D2O (10/1, v/v) and then treated with TBAF in the presence of NMA and DBU. With the exception of the stimulus, these are the same conditions that had been used initially to evaluate the depolymerization of Al-P1. H NMR spectroscopic monitoring of the TBS-P2 depolymerization under these conditions clearly showed a decrease of backbone methylene signals and concomitant increase of small molecule products generated by trapping of the reactive quinone methide with NMA and water (Figure , see full details in the Supporting Information). This result contrasted with the hindered degradation of Al-P1 after triggering (Figures ), confirming the importance of the linker length.