Open-Vessel and Scalable Synthesis of Linear and Branched Poly(meth)acrylic Acid via Light-Mediated Atom Transfer Radical Polymerization in Water
Bibliographic record
Abstract
High Resolution Image Download MS PowerPoint Slide Poly(methacrylic acid) (PMAA) and poly(acrylic acid) (PAA) are synthesized on a large scale by conventional free radical polymerization (FRP). The access to architectural diversity by FRP is limited but can be addressed by reversible deactivation radical polymerization (RDRP), including atom transfer radical polymerization (ATRP). ATRP of methacrylic acid (MAA) and acrylic acid (AA) is challenging due to lactonization via the displacement of halide ( X ) end groups by penultimate carboxylate anions (CO 2 – ) and the loss of chain-end functionality. Despite the successful polymerization of MAA or AA ((M)AA) using various RDRP methods, the oxygen-tolerant photo-ATRP of (M)AA has not yet been investigated. Herein, photo-ATRP of (M)AA in open vials was enabled by adding sodium pyruvate (SP) or pyruvic acid (PA) to the polymerization mixture. Photoirradiation of SP/PA generated radicals and enhanced the rate of polymerization at ambient temperature, which diminished lactonization reactions. This method allowed the synthesis of PMAA or PAA (P(M)AA) at low pH (1 to 3.2) with relatively low dispersity ( Đ = 1.10–1.38 under optimized conditions) and good agreement between the theoretical molecular weight ( M n,theo ) and the absolute molecular weight ( M n,abs ). Photo-ATRP allowed the synthesis of PMAA in ≤1 h and also the synthesis of branched PAA by copolymerization with α-haloacrylic acids. Additionally, successful grafting of MAA from poly(vinylidene fluoride- co -chlorotrifluoroethylene) (PVDF- co -CTFE) was achieved in dispersed aqueous media.
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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) | 0.001 | 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 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
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".