Photoageing of cardanol: characterization, circumvention by side chain methoxylation and application for photocrosslinkable polymers

Abstract

The photosensitivity of cardanol has been evaluated using a multi-technique approach. Among other techniques, size exclusion chromatography, matrix assisted laser desorption ionization mass spectrometry and their off line coupling provided useful details on the macroscopically observed yellowing and insolubility of cardanol under UV activation by analyzing photoproducts at the molecular level. Evidencing the implication of the unsaturations borne by the cardanol side chain in a crosslinking process, an original synthesis route leading to its complete methoxylation has been proposed as a way to lower the photosensitivity of cardanol. Using a similar set of analytical techniques, this newly synthesized methoxylated cardanol has appeared more resistant towards UV exposure, without any crosslinking but a simple dimerization preserving its solubility. As a direct application, copolymers made from methyl methacrylate, cardanol and methoxylated cardanol have been synthesized, and their photocrosslinking ability was found to depend on the content of the two latter co-monomers, as a preliminary step towards the production of photocrosslinkable bio-based polymers with a tunable UV curing propensity. † Electronic supplementary information (ESI) available: Structure of the cardanol components, UV/Vis spectra and SEC-UV/Vis spectra of UV-exposed cardanol, MALDI-MS spectra of intermediate products to the methoxylated cardanol, UV/Vis spectrum of UV-exposed methoxylated cardanol, MALDI-MS spectra of the CEAcry and MCEAcry monomers, SEC chromatograms, MALDI-MS spectra and SEC-MALDI-MS spectra of a commercially available cardoxyethanol. See

Reactive plasticization of poly(lactide) with epoxy functionalized cardanol

“…3c) display a distinct broad peak detected in the shortest elution volumes (6-9 ml), validating the presence of high molecular weight compounds bearing UV-active groups. The two main peaks at the longer retention times are assigned to epoxidized cardanol and dimers as already characterized for NC514 [37] (NC514S named ECard in this work is a purified grade of NC514-see Figure S1 in the Supporting Information-but of similar chemical nature). Note that the decrease of intensity of the dimer peak for the three formulated samples are compared to the pristine ECard.…”

“…The degradation of the PLA sample, i.e. cleavage of bonds upon thermo‐oxidative processes leading to the mass reduction, and the complexity of ECard (expected to be a diepoxidized cardanol but most likely containing residual phenol groups instead of epoxy and dimers as impurities account for the occurrence of several mass distributions. The detection of a complex isotopic pattern for each oligomer in Figure S2c is in accordance with the presence of at least one cardanol moiety along the backbone (consecutive peaks spaced by 2 Da owing to the polyunsaturated side chain constituting a preliminary clue at a molecular level for the grafting of NC514S on PLA chains.…”

“…In Addition to FTIR characterization, SEC analyses were also conducted on a device equipped with a UV detector. Cardanol moiety is indeed UV active at 280 nm [37] while PLA is transparent at such wavelength. Since PLA is of higher molecular weight than Ecard, any peak detected at a short retention time in the SEC chromatogram of a PLA/ECard/ETPB sample would highlight any grafting of cardanol on the PLA backbones.…”

Functionalization of styrene–butadiene rubber with meta‐pentadecenyl phenol for better processing: A multifunctional additive and renewable resource

“…The FTIR spectrum of SBR showed characteristic peaks at 699, 770, 911, 1073, 1218, 1449, 1638, 2844, 2918, and 3061 cm 21 , whereas the phenolic AOH group in cardanol gave rise to absorption bands at 3349 and 1588 cm 21 , respectively, due to the OAH and PhAO stretching vibrations. 40 However, there was no peak beyond 3000 cm 21 in the neat SBR. On the other hand, C-g-SBR exhibited an absorption peak at 3439 cm 21 in addition to all of the other characteristic peaks present in SBR.…”

“…The FTIR spectrum [Figure (b)] of both cardanol and SBR exhibited similar characteristic peaks because of their close resemblance to hydrophobic nature environments except that cardanol contained a phenolic OH group. The FTIR spectrum of SBR showed characteristic peaks at 699, 770, 911, 1073, 1218, 1449, 1638, 2844, 2918, and 3061 cm −1 , whereas the phenolic OH group in cardanol gave rise to absorption bands at 3349 and 1588 cm −1 , respectively, due to the OH and PhO stretching vibrations . However, there was no peak beyond 3000 cm −1 in the neat SBR.…”