Electrocatalytic TEMPO-mediated oxidation of cellulose nanocrystals: gaining a mechanistic understanding
Bibliographic record
Abstract
Electrocatalytic (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO) and 4-acetamido TEMPO-mediated oxidation were used in the regioselective functionalization of cellulose nanocrystals (CNCs) to achieve tunable carboxyl and aldehyde contents. Compared to conventional TEMPO-mediated oxidation that is optimized for the secondary oxidizing agents used, this electrocatalytic approach has no additional chemicals; however, the reaction mechanism remains unexplored. This work elucidated the pH-dependence of the electrocatalytic oxidation of uncharged cotton-derived CNCs and demonstrated that the oxoammonium form of TEMPO (TEMPO+) reacts faster with CNCs at higher pH. Counterintuitively, CNCs with the highest carboxyl content were produced at intermediate pH values, reaching an impressive degree of surface substitution of 0.47 – corresponding to 94 % of the theoretical limit. In alkaline conditions, the degree of carboxylation decreased, which was attributed to β-elimination. The rate-limiting step was determined to be the regeneration of TEMPO+ and switching from a non-divided electrochemical cell to a divided one mitigated the issue. The use of a divided cell also helps the cathodic production of H 2 gas, a desirable co-product formed at the counter electrode during the reaction. The electrocatalytically-oxidized CNCs were colloidally stable, maintained their crystallinity/size and had carboxyl contents similar to lab-made chemically-driven TEMPO-oxidized CNCs and five-times higher than commercially-available carboxylated CNCs.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".