RAFT Synthesis of Acrylic Copolymers Containing Poly(ethylene glycol) and Dioxolane Functional Groups: Toward Well-Defined Aldehyde Containing Copolymers for Bioconjugation
Bibliographic record
Abstract
Copolymers of poly(ethylene glycol) methyl ether methacrylate (PEGMA) and one of two dioxolane-containing monomers, (2,2-dimethyl-1,3-dioxolane)methyl acrylate (DDMA) and (2,2-dimethyl-1,3-dioxolane)methyl acrylamide (DDMAA), were successfully synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization. RAFT copolymerization was performed in dimethylformamide (DMF) at 70 °C for 24 h using 4,4′-azobis(4-cyanovaleric acid) as initiator and N -(sodium ethane sulfonic acid)-2-((thiobenzyl)sulfanyl)proprionamide (CTA 1), 4-cyano-4-((thiobenzoyl)sulfanyl)pentanoic acid (CTA 2), or S, S ′-bis(α,α′-dimethyl-α′′-acetic acid)trithiocarbonate (CTA 3) as the chain transfer agent (CTA). Control over molecular weight and composition was achieved by altering the CTA concentration and the monomer feed ratio respectively. The resulting copolymers had narrow molecular weight distributions (polydispersity indices typically between 1.2 and 1.3), while monomer conversions were typically 60%. Kinetic studies revealed that PEGMA was consumed at a higher rate than the comonomers over a given time. The molecular weight of the copolymer increased linearly with conversion, while a low polydispersity was maintained throughout. The copolymerization reactivity ratios were determined using the Mayo−Lewis method. After copolymerization, the dioxolane functional groups were deprotected to form 1,2-diol groups and subsequently oxidized with HIO 4 to form reactive aldehyde groups. Subsequent chemical modification of the dioxolane moieties to aldehyde groups showed no adverse effects in terms of degradation of the copolymer (specifically ester linkages). The advantage of the current synthesis over direct copolymerization of aldehyde-based monomers is the stability of the 1,2-diol moiety compared to the corresponding aldehyde copolymer. The availability of the aldehyde groups along the polymer backbone to form stable conjugates with amine containing molecules was confirmed via a reaction with the iron chelating drug desferrioxamine (DFO). Conjugation was achieved via an aldamine reaction, followed by a reduction of the resulting Schiff base to a secondary amine. Full characterization of the copolymers was performed using NMR spectroscopy and GPC−MALLS, while UV−vis absorption spectroscopy was used to determine the efficiency of DFO conjugation.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".