Main Chain-Containing Azo-Tetraphenyldiaminobiphenyl Photorefractive Polymers
Bibliographic record
Abstract
The design of polymeric materials with optimized photoconductivity and nonlinear optical properties is of major interest for emerging optical applications using photorefractive properties. This paper reports the synthesis and preliminary optical characterization of a series of novel, fully functionalized, photorefractive polymers. They were synthesized by a post azo coupling reaction of a polyether carbonate polymer based on the charge transport N,N,N‘,N‘-tetraphenyl-diaminobiphenyl group with 4-nitrobenzene-diazonium tetrafluoroborate by phase transfer catalysis. The amount of the inserted 4-nitro-phenyl-azo group was between 0.1 and 1.7 per structural unit. These polymers absorb in the UV−vis range, because of the presence of donor−acceptor substituted azobenzene chromophores. Light induced change of the refractive index was studied by birefringence measurements (λ probe = 632.8 nm) as a function of azo content in thin films with thickness ranging from 200 to 500 nm. Surface relief grating inscription was also demonstrated in the same polymer thin films, with a weak surface relief amplitude and a low diffraction efficiency (<1%). These results indicate a relatively low mobility of the azobenzene chromophores. Photoconductivity was studied by measuring the photocurrent through 40 μm thick samples where a metal-free phthalocyanine layer deposited on electrodes served as charge generator. These samples have exceptionally high photoconductivity compared to other composite materials. In addition, preliminary two-beam coupling experiments demonstrated unambiguously the photorefractive effect under low poling field (2.5 V/μm) at room temperature, but no net gain was obtained because of a high absorption coefficient at 632.8 nm.
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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 | 0.000 |
| 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".