Laponite-Doped Poly(acrylic acid-<i>co</i>-acrylamide) Hydrogels
Bibliographic record
Abstract
Electroacoustic characterization of soft nanocomposites has provided unique insights into the microstructure of soft nanocomposites, including nanoparticle (NP)-doped hydrogels and polyelectrolyte hydrogels without NPs. An outstanding problem is how to interpret the electrokinetic sonic amplitude (ESA) of charged hydrogels bearing charged NPs because both components generate an acoustic response to the electrical forcing. To this end, we study a series of Laponite XLG-doped, neutralized poly(acrylic acid- co -acrylamide) hydrogels, drawing principally on the ESA, electrical conductivity, and linear viscoelastic rheology. The hydrogel charge density was varied by the fraction of acrylic acid monomer f AAc = 0–1 while maintaining the total monomer concentration ≈8 wt % with Laponite concentration ≈0.85 wt %. Upon comparison of data from this study to those in a recent benchmark study of charged hydrogels without NPs, Laponite doping increased the electroacoustic signal and ionic conductivity but decreased the hydrogel storage modulus. Mechanistic theoretical models predicting how the real part of the ESA (at low frequency) and ionic conductivity of polyelectrolyte hydrogels depend on f AAc were extended to Laponite-doped hydrogels, together furnishing an estimate of the partial molar volume of acrylamide (in polymer form) that is close to the value for pure acrylamide (based on its density and molecular weight). The generally lower storage modulus with Laponite doping contrasts with previous studies of Laponite-doped polyacrylamide and poly(acrylic acid) hydrogels and solutions. This seems to reflect the high degree of neutralization, which transforms an attraction between protonated carboxyl moieties and Laponite to an electrostatic repulsion. The hindering effects of polymerization and cross-linking on acrylic acid- co -acrylamide networks were also investigated by comparing the ESA and conductivity of hydrogels with their monomer solution counterparts. Systematically varying the ratio of charged to uncharged monomers, with and without chemical cross-linking, provides insights to benefit a broad range of technological applications for hydrogel nanocomposites.
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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".