Dipolar-depletion: study of a field-tunable colloid-polymer system
Bibliographic record
Abstract
Colloidal gels are an important class of materials with mesoscale building blocks, and they have wide-ranging applications, from water purification to cement to biotechnology. However, the formation of colloidal gels is beset by inadequate control over phase behaviour and slow aging kinetics. In this work, we report on experiments that examine structure, structural relaxation and dynamics in colloid-polymer suspensions, with fine, tunable control: the concentration of non-adsorbing polymer controls the strength of a depletion attraction, and an external electric field induces dipolar interactions that are instantly switchable and tunable in strength. ßWith these switchable interactions, we have studied the “dipolar-depletion” phase diagram in real space via fluorescence confocal laser scanning microscopy. We show combining depletion with dipolar interactions, at lower polymer concentrations, lowers the field threshold for observing ordered sheet-like dipolar structures. At intermediate polymer concentrations, depletion-induced clusters suppress field-induced ordering. At high depletion strengths, we can create partially ordered gel states. We also quantitatively characterize the transition from reversible to irreversible structures, and use the cycling of the external field to accelerate aging in a gel-forming system. For processes that take months or years to study, such as the collapse of certain gels, such accelerated aging would prove extremely useful. In addition, we characterize our model system by measuring the Zeta potential and charge on the colloids that we use to study the phase diagram via both AC and DC microelectrophoresis. We compare AC and DC measurements and find that there is no electrode polarization effect in a partially polar solvent.
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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 | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.003 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| 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".