Synthesis of Poly(alkyl/arylphosphazenes) via the Ambient Temperature Phosphite-Mediated Chain-Growth Polycondensation of (<i>N</i>-Silyl)bromophosphoranimines
Bibliographic record
Abstract
The room temperature addition of stoichiometric amounts of trimethyl phosphite, P(OMe) 3, to N -silyl(halogeno)organophosphoranimines BrRR′P═NSiMe 3 in chlorinated solvents led to the direct formation of high molecular weight polyphosphazenes [RR′P═N] n . The majority of polymerizations were complete within 18 h. The polymers prepared include poly(dialkylphosphazenes) (e.g., [ n Bu 2 P═N] n 1b ), poly(alkylarylphosphazenes) (e.g., [PhMeP═N] n 1d ), new materials featuring unsaturated substituents (e.g., [ n Hex{H 2 C═C(H)CH 2 }P═N] n 1n ), and random copolymers (e.g., {[PhMeP═N] x −[Ph n BuP═N] y } where x: y = 2:1, 7a ). The precursor silylaminophosphines RR′P−N(SiMe 3 ) 2 ( 5a − q ) and bromo(silylamino)phosphoranimines BrRR′P═NSiMe 3 ( 4a − q ) were synthesized and fully characterized prior to polymerization studies. The presence of alkoxy, carboranyl, and/or phenyl substituents on the N -silylbromophosphoranimines, as found in BrEt[CF 3 CH 2 O]P═NSiMe 3 ( 4g ), Br(2-[Me]- o -C 2 B 10 H 10 )EtP═NSiMe 3 ( 4h ), or BrPh 2 P═NSiMe 3 ( 4i ), respectively, was found either to severely retard or to preclude polymerization altogether. The mild reaction conditions enabled the preparation of polyphosphazenes that are substituted with reactive alkyne groups (e.g., R = Et, R′ = −CH 2 C≡CSiMe 3 1p ), materials that have not been accessible using high-temperature thermal routes. These moieties undergo further convenient chemical transformations as illustrated by deprotection of 1p by TBAF·3H 2 O (TBAF = tetra( n -butyl)ammonium fluoride) as well as chemical cross-linking with the disiloxane HMe 2 SiOSiMe 2 H in the presence of Karstedt’s catalyst. The polyphosphazene materials were characterized by a variety of techniques including 1 H, 13 C, and 31 P NMR spectroscopy and GPC and, in selected cases, by IR, DLS, TGA, DSC, and WAXS.
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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 | 0.001 |
| 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 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 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".