Surface modification of cellulose nanocrystals with cetyltrimethylammonium bromide
Bibliographic record
Abstract
Cellulose nanocrystals (CNCs) prepared by sulfuric acid hydrolysis of cotton were surface modified with cetyltrimethylammonium bromide (CTAB). Essentially, the counterions of the CNC surface sulfate ester groups are exchanged for cetyltrimethylammonium (CTA+), which acts as a bulky, amphiphilic cation. The CTAB-modified CNCs were thoroughly purified to remove surfactant that was nonelectrostatically bound. The surface modification could be tailored from 50 to 100% charge coupling efficiency by varying the reaction conditions. The main factor that influenced coupling efficiency was ionic strength; increasing the ionic strength screened electrostatic interactions, which led to decreased surfactant adsorption. Adsorption isotherms of CTAB on model CNC films, measured by surface plasmon resonance spectroscopy, indicated an increase in adsorbed surfactant amount with increasing bulk CTAB concentration without achieving saturation in the concentration range studied. CTABmodified CNCs were unstable in water but formed stable colloidal suspensions in ethanol, which transitioned into a continuous gel-like chiral nematic liquid crystal at relatively low concentrations (~4 wt. %) but did not phase separate into isotropic and anisotropic phases. The particle size and morphology of the CTAB-modified CNCs were unchanged compared to the native CNCs but were more thermally stable and less hydrophilic after the surface modification reaction.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| 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) | 0.001 | 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 source (direct Gemma or distilled Codex), 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".