Diffusion of Model Hydrophobic Alkali-Swellable Emulsion Associative Thickeners
Bibliographic record
Abstract
Diffusion coefficients of hydrophobically modified alkali-swellable (HASE) associating polymers (APs) in aqueous solution were measured using pulsed gradient spin-echo (PGSE) nuclear magnetic resonance (NMR). HASE APs consist of a copolymer of methacrylic acid and ethyl acrylate to which hydrophobic “sticker groups” are attached through a poly(ethylene oxide) (PEO) “spacer arm”. Two series of HASE APs were investigated: one in which the length of the hydrophobic alkyl chain was varied (C x E 35 ) and another in which the length of the PEO spacer arm was varied (C 20 E y ). With increasing hydrophobe or PEO spacer arm length the average diffusion coefficient decreased, reflecting the viscosity enhancement produced by the associating network formed by HASE polymers. The effect of external variables such as concentration, pH, and temperature mirrored established rheological properties for such systems. The average diffusion behavior, however, was the result of a superposition of two contributions, one slow ( D 0 < 1 × 10 -11 m 2 s -1 ) and one fast ( D 0 ≈ 1 × 10 -10 m 2 s -1 ) diffusing. Changing the hydrophobe chain length or the PEO spacer arm length modulated the proportion of the fast and slow diffusing populations but had relatively little effect on the diffusion coefficients of the two populations. Precipitation of the HASE AP from THF−HCl aq produced two fractions, one enriched with hydrophobe and the other correspondingly depleted relative to the global average. The fractions enriched and depleted with respect to hydrophobe exhibited diffusion coefficients similar to the fast and slow diffusing populations. We conclude that the hydrophobe is inhomogeneously distributed among the HASE AP chains, that the population enriched with hydrophobe forms more compact structures capable of faster diffusion, and that the effects of hydrophobe chain length and PEO spacer arm length on HASE AP solution viscosity are mediated by their influence on the coupling of the hydrophobe enriched population into the slow-diffusing hydrophobe-depleted population.
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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 | 0.000 | 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) | 0.002 | 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".