Synthesis and Characterization of Polymer Brushes of Poly(<i>N</i>,<i>N</i>-dimethylacrylamide) from Polystyrene Latex by Aqueous Atom Transfer Radical Polymerization
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Bibliographic record
Abstract
Negatively charged polystyrene latex was synthesized, and a copolymer shell of 2-(methyl-2‘-chloropropionato)ethyl acrylate (HEA-Cl) and styrene was added, from which poly( N, N -dimethylacrylamide) (PDMA) was polymerized by atom transfer radical polymerization in aqueous suspension at room temperature. Increasing monomer concentration in the presence of CuCl or CuBr and one of three ligands ( N,N, N ‘, N ‘, N ‘ ‘-pentamethyldiethylenetriamine (PMDETA), 1,1,4,7,10,10-hexamethyltriethylenetetramine (HMTETA), and tris[2-(dimethylamino)ethyl]amine (Me 6 TREN)) produced grafts whose molecular weight increased to over 600 000 and polydispersities in the range of 1.3−1.8, determined from chains recovered following cleavage by base. Hydrodynamic brush thicknesses were 70−800 nm, and average chain separations, calculated from M n and the mass of polymer recovered per particle, varied from 4.0 to 1.1 nm. Very high grafting densities were achieved with good molecular weight control, the highest densities yet reported for high molecular weight polymer chains grown from a surface. Control of the polymerization was improved by addition of Cu(II) to enhance deactivation of free radicals, by including a low concentration of exogenous hydrophobic initiator at high monomer concentration and by reducing latex concentration. Increasing the concentration of exogenous initiator reduced graft thickness but eliminated control over the polydispersity. The unusual conditions required for optimization of the reaction and the observation of decreasing chain separation as M n increased were explained by invoking a model of the particle surface that took into account the finite depth and high copolymer concentration of the region in which chains were initiated and particularly the fixed charges due to the sulfate initiator of shell copolymerization.
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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 | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 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 it