Synthesis and characterization of novel dendritic (arborescent, hyperbranched) polyisobutylene–polystyrene block copolymers
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Bibliographic record
Abstract
Abstract The synthesis of novel arborescent ( arb ; randomly branched, “tree‐like,” and often called “hyperbranched”) block copolymers comprised of rubbery polyisobutylene (PIB) and glassy polystyrene (PSt) blocks ( arb ‐PIB‐ b ‐PSt) is described. The syntheses were accomplished by the use of arb ‐PIB macroinitiators (prepared by the use of 4‐(2‐methoxyisopropyl) styrene inimer ) in conjunction with titanium tetrachloride (TiCl 4 ). The effect of reaction conditions on blocking of St from arb ‐PIB was investigated. Purified block copolymers were characterized by 1 H NMR spectroscopy and Size Exclusion Chromatography (SEC). arb ‐PIB‐ b ‐PSt with 11.7–33.8 wt % PSt and M n = 468,800–652,900 g/mol displayed thermoplastic elastomeric properties with 3.6–8.7 MPa tensile strength and 950–1830% elongation. Samples with 26.8–33.8 wt % PSt were further characterized by Atomic Force Microscopy (AFM), which showed phase‐separated mixed spherical/cylindrical/lamellar PSt phases irregularly distributed within the continuous PIB phase. Dynamic Mechanical Thermal Analysis (DMTA) and solvent swelling of arb ‐PIB‐ b ‐PSt revealed unique characteristics, in comparison with a semicommercial PSt‐ b ‐PIB‐ b ‐PSt block copolymer. The number of aromatic branching points of the arb ‐PIB macroinitiator, determined by selective destruction of the linking sites, agreed well with that calculated from equilibrium swelling data of arb ‐PIB‐ b ‐PSt. This method for the quantitative determination of branching sites might be generally applicable for arborescent polymers. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1811–1826, 2005
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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) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.002 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.001 | 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 it