4-Vinyl Guaiacol: A Key Intermediate for Biobased Polymers.

In order to contribute to the shift from petro-based chemistry to biobased chemistry, necessary to minimize the environmental impacts of the chemical industry, 2-methoxy-4-vinylphenol (4-vinyl guaiacol, 4VG) was used to synthesize a platform of biobased monomers. Thus, nine biobased monomers were successfully prepared. The synthesis procedures were investigated through the green metrics calculations in order to quantify the sustainability of our approaches. Their radical homopolymerization in toluene solution initiated by 2,2'-azobis(2-methylpropionitrile) (AIBN) was studied and the effect of residual 4VG as a radical inhibitor on the kinetics of polymerization was also explored. The new homopolymers were characterized by proton nuclear magnetic resonance (1H-NMR) spectroscopy, size exclusion chromatography and thermal analyses (dynamical scanning calorimetry DSC, thermal gravimetric analysis TGA). By varying the length of the alkyl ester or ether group of the 4VG derivatives, homopolymers with Tg ranging from 117 °C down to 5 °C were obtained. These new biobased monomers could be implemented in radical copolymerization as substitutes to petro-based monomers to decrease the carbon footprint of the resulting copolymers for various applications.

Calcium-catalysed synthesis of amines through imine hydrosilylation: an experimental and theoretical study.

A method to reduce aldimines through hydrosilylation is reported. The catalytic system involves calcium triflimide (Ca(NTf2)2) and potassium hexafluorophosphate (KPF6) which have been shown to act in a synergistic manner. The expected amines are obtained in fair to very high yields (40-99%) under mild conditions (room temperature in most cases). To illustrate the potential of this method, a bioactive molecule with antifungal properties was prepared on the gram scale and in high yield in environmentally friendly 2-methyltetrahydrofuran. Moreover, it is shown in this example that the imine can be prepared in situ from the aldehyde and the amine without isolating the imine. The mechanism involved has been explored experimentally and through DFT calculations, and the results are in accordance with an electrophilic activation of the silane by the calcium catalyst.

Phosphorus Modified Cardanol: A Greener Route to Reduce VolaTile Organic Compounds and Impart Flame Retardant Properties to Alkyd Resin Coatings.

Novel phosphorylated cardanol molecules based on phosphonate (PO3CR) and phosphate (PO4CR) functions were synthetized. Those molecules have two main actions which are described in this article: the reduction in volatile organic compounds (VOC) and the development of flame retardant (FR) properties conferred on alkyd resins used as coatings for wood specimen. Phosphorylated cardanol compounds have been successfully grafted by covalent bonds to alkyd resins thanks to an auto-oxidative reaction. The impact of the introduction of PO3CR and PO4CR on the film properties such as drying time and flexibility has been studied and the thermal and flame retardant properties through differential scanning calorimeter, thermogravimetric analysis and pyrolysis-combustion flow calorimeter. These studies underscored an increase in the thermal stability and FR properties of the alkyd resins. In the cone calorimeter test, the lowest pHRR was obtained with 3 wt% P of phosphate-cardanol and exhibited a value of 170 KW.m-2, which represented a decrease of almost 46% compared to the POxCR-free alkyd resins. Moreover, a difference in the mode of action between phosphonate and phosphate compounds has been highlighted. The most effective coating which combined excellent FR properties and good coating properties has been obtained with 2 wt% P of phosphate-cardanol. Indeed, the film properties were closed to the POxCR-free alkyd resin and the pHRR decreased by 41% compared to the reference alkyd resin.

Large Polyhedral Oligomeric Silsesquioxane Cages: The Isolation of Functionalized POSS with an Unprecedented Si18 O27 Core.

The synthesis of organo-functionalized polyhedral oligomeric silsesquioxanes (POSS, (R-SiO1.5 )n , Tn ) is an area of significant activity. To date, T14 is the largest such cage synthesized and isolated as a single isomer. Herein, we report an unprecedented, single-isomer styryl-functionalized T18 POSS. Unambiguously identified among nine possible isomers by multinuclear solution NMR (1 H, 13 C, and 29 Si), MALDI-MS, FTIR, and computational studies, this is the largest single-isomer functionalized Tn compound isolated to date. A ring-strain model was developed to correlate the 29 Si resonances with the number of 6-, 5-, and/or 4-Si-atom rings that each non-equivalent Si atom is part of. The model successfully predicts the speciation of non-equivalent Si atoms in other families of Tn compounds, demonstrating its general applicability for assigning 29 Si resonances to Si atoms in cage silsesquioxanes and providing a useful tool for predicting Si-atom environments.

May Trifluoromethylation and Polymerization of Styrene Occur from a Perfluorinated Persistent Radical (PPFR)?

The radical polymerization of styrene (St) initiated by a trifluoromethyl radical generated from a perfluorinated highly branched persistent radical (PPFR) is presented with an isolated yield above 70 %. The release of . CF3 radical occurred from a temperature above 85 °C. Deeper 1 H and 19 F NMR spectroscopies of the resulting fluorinated polystyrenes (CF3 -PSts) evidenced the presence of both CF3 end-group of the PSt chain and the trifluoromethylation of the phenyl ring (in meta-position mainly). [PPFR]0 /[St]0 initial molar ratios of 3:1, 3:10 and 3:100 led to various molar masses ranging from 1750 to 5400 g mol-1 in 70-86 % yields. MALDI-TOF spectrometry of such CF3 -PSts highlighted polymeric distributions which evidenced differences between m/z fragments of 104 and 172 corresponding to styrene and trifluoromethyl styrene units, respectively. Such CF3 -PSt polymers were also compared to conventional PSts produced from the radical polymerization of St initiated by a peroxydicarbonate initiator. A mechanism of the polymerization is presented showing the formation of a trifluoromethyl styrene first, followed by its radical (co)polymerization with styrene. The thermal properties (thermal stability and glass transition temperature, Tg ) of these polymers were also compared and revealed a much better thermal stability of the CF3 -PSt (10 % weight loss at 356-376 °C) and a Tg of around 70 °C.

Effect of the Molecular Structure of Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (P(3HB-3HV)) Produced from Mixed Bacterial Cultures on Its Crystallization and Mechanical Properties.

Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (P(3HB-3HV)) copolymer's properties depend on (i) the molar fraction of comonomers, (ii) the overall molar mass, and (ii) the chemical compositional distribution. This work aims at providing a better understanding of the effect of the P(3HB-3HV) molecular structure, produced from mixed cultures and waste feedstock, on copolymer crystallization and tensile properties. Conventional biopolymer characterization methods (differential scanning calorimetry, X-ray diffraction, and polarized optical microscopy) were coupled to both classical one-dimensional (1H and 13C) and advanced two-dimensional (diffusion-ordered spectroscopy (DOSY) and 1H/13C heteronuclear single quantum coherence (HSQC)) nuclear magnetic resonance (NMR) spectroscopy techniques. The obtained results evidenced that (i) a high-quality copolymer could be achieved, even from a waste feedstock; (ii) increasing the 3HV content displayed a positive impact on P(3HB-3HV) mechanical properties only if good interactions between 3HB and 3HV moieties were established; and (iii) the purification process eliminated short-length 3HV-rich chains and promoted homogeneous co-crystallization. Such optimized microstructures enabled the maximal stress and strain at break to be increased by +41.2 and +100%, respectively.

Functionalised polyhedral oligomeric silsesquioxane with encapsulated fluoride - first observation of fluxional SiF interactions in POSS.

The synthesis of a styryl functionalised POSS incorporating an encapsulated fluoride ion within a (SiO1.5)8 cage (T8-F) is reported. It was characterised by single crystal XRD, MALDI-MS, FTIR, solution (29Si, 19F, 13C, 1H) and solid state (29Si, 19F) NMR. In the absence of 1H decoupling, the 29Si solution NMR spectrum exhibited a triplet of doublets. In contrast, 1H, 19F and 1H/19F double-decoupling resulted in two, three and one signal, respectively, being consistent with a single Si site whose 29Si NMR signal is modulated by both the proximal aromatic-ring protons and fluoride. The associated SiF coupling constant (2.5 Hz) is substantially lower than expected for a covalent Si-F bond and arises from a fluxional SiF covalent effect in which the F- interacts equivalently with all eight Si atoms. Additional variable temperature NMR studies demonstrated a threshold at -5 °C below which no SiF interactions are observed, and above which an increasing SiF covalent character occurs.