Viscoelastic Properties of Arborescent Polystyrene-<i>graft</i>-polyisoprene Copolymers
Bibliographic record
Abstract
Arborescent polymers are highly branched macromolecules obtained from successive grafting reactions according to a generation-based scheme. Grafting side chains onto a linear substrate randomly functionalized with coupling sites thus yields a generation zero (G0) polymer, with a comb-branched structure. Further cycles of substrate functionalization and grafting lead to arborescent polymers of generations G1, G2, etc., with a dendritic architecture. Arborescent copolymers can also be obtained when side chains with a chemical composition different from the substrate are used in the last grafting cycle. Copolymers of generations G0−G3 were thus obtained by grafting polyisoprene chains with a high cis -1,4-unit content onto polystyrene substrates. The dynamic mechanical behavior of the arborescent polystyrene- graft -polyisoprene copolymers was investigated as a function of side-chain length and generation number. The zero-shear viscosity of the copolymers was lower than for linear polyisoprenes of comparable molecular weight, but its scaling behavior as a function of molecular weight was consistent with entanglement formation. The zero-shear recoverable compliance increased with the overall molecular weight of the copolymers to reach values up to 10 times larger than for the linear analogues. Isoprene copolymers of generations G0 and G1 displayed viscous flow behavior at low shear rates, their terminal relaxation time increasing with the molecular weight of the side chains. A relaxation at intermediate frequencies, associated with the polyisoprene chains, appeared at similar frequencies for copolymers of different generations with side chains of comparable molecular weights. The frequency dependence of the modulus observed for highly branched (G2 and G3) isoprene copolymers was analogous to microgels and filled polymer systems, the modulus−frequency master curves displaying thermorheological complexity with breakdown of the time−temperature superposition principle for copolymers with short side chains.
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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".