Amphiphilic Block Random Copolymers: Influence of pH and Ionic Strength on Aqueous Solution Properties
Bibliographic record
Abstract
Aqueous solution properties of polystyrene- b -poly(styrene- r -acrylic acid), PS- b -P(S- r -AA), block–random copolymers (BRC) as a function of pH and ionic strength are reported using light scattering and surface tensiometry. Critical aggregation concentrations (CAC) are two orders of magnitude greater than similar PS- b -PAA block copolymers at pH >7.7; however, the CAC approaches that of block copolymers as the pH approaches the p K a of the BRC (pH = 7.0, p K a ∼6.3). Aggregation numbers ( N agg ) between 5 and 26 are observed under alkaline conditions, about one to two orders of magnitude lower than those of PS- b -PAA block copolymers. Lowering the pH from 9.5 to 7.0 and increasing the ionic strength from 30 to 1000 mM reduced CAC and increased N agg due to a lower effective charge along the BRC chains. Analysis of the multichain aggregates using a core–corona spherical model showed that the PS- r -PAA blocks are compressed on the surface of the PS core due to the favorable mixing of the PS units. The BRCs are surface active above 0.1 g/L and slow to adsorb to interfaces. Results are related to previous work with emulsion polymerizations stabilized by BRC, suggesting that the structure of the aggregates and the slow adsorption kinetics play significant roles in the emulsion polymerization mechanism.
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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) | 0.000 | 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".