Nitrogen‐Containing Polymers Derived from Terpenes: Possibilities and Limitations

Nitrogen-containing polymers are widely applied materials, including polyamides, polyurethanes, and polyureas as well as epoxy thermosets. Their indispensability and the urgent need to replace fossil-based polymers considering more sustainable alternatives lead to significant efforts in exploring renewable feedstock as potential new building blocks. Being obtained from non-edible plant parts and often occurring as waste products, terpenes represent a promising group of renewable compounds that are of possible interest in the synthesis of nitrogen-containing polymers. The structural diversity of terpenes in combination with the mechanical properties that nitrogen-containing moieties bring into polymers can give rise to novel biobased materials that outstand mechanical and thermal properties of conventional fossil-based counterparts. In this review, an overview of the use of terpene compounds in the synthesis of nitrogen-containing polymers is given, covering different approaches to make use of terpenes as a valuable pool of renewable monomers

Photosensitizer Drug Delivery via an Optical Fiber

: An optical fiber has been developed with a maneuverable miniprobe tip that sparges O2 gas and photodetaches pheophorbide (sensitizer) molecules. Singlet oxygen is produced at the probe tip surface which reacts with an alkene spacer group releasing sensitizer upon fragmentation of a dioxetane intermediate. Optimal sensitizer photorelease occurred when the probe tip was loaded with 60 nmol sensitizer, where crowding of the pheophorbide molecules and self-quenching were kept to a minimum. The fiber optic tip delivered pheophorbide molecules and singlet oxygen to discrete locations. The 60 nmol sensitizer was delivered into petrolatum; however, sensitizer release was less efficient in toluene-d8 (3.6 nmol) where most had remained adsorbed on the probe tip, even after the covalent alkene spacer bond had been broken. The results open the door to a new area of fiber optic-guided sensitizer delivery for the potential photodynamic therapy of hypoxic structures requiring cytotoxic control

Poly(3-hexylthiophene) based block copolymers prepared by "click" chemistry

pi-Conjugated block copolymers have been prepared from terminal azide functionalized polystyrenes (PS) and alkyne functionalized poly (3-hexylthiophene)s (P3HT) via a copper(I) catalyzed Huisgen [3 + 2] dipolar cycloaddition reaction. The functionalized alpha-azido-PS homopolymer was prepared by atom transfer radical polymerization from a specifically designed initiator bearing the azide function, whereas omega-ethynyl-P3HT and a,alpha,omega-pentynyl-P3HT were synthesized by a modified Grignard metathesis polymerization using alkynyl Grignard derivatives. The electronic environment of the alkynyl end groups was shown to be decisive in determining triazole ring formation

Pi-conjugated (co)polymers for organic electronics

International audienc

Main-​chain poly(fullerene) multiblock copolymers as organic photovoltaic donor-​acceptors and stabilizers

A multi-​block copolymer based on main-​chain fullerene repeating units is used in org. photovoltaic devices for the first time. A poly(fullerene) (PFDP) is linked at the chain-​ends to poly(3-​hexylthiophene) (P3HT) to give poly[poly(3-​hexylthiophene)​-​block-​poly{([1,​4]​-​fullerene)​-​alt-​[1,​4-​dimethylene-​2,​5-​bis(cyclohexylmethyl ether)​phenylene]​}​] (P3HT-​b-​PFDP)​. While normal devices give poor results, inverted architectures result in near 50-​fold improvements in performances to a block copolymer efficiency of 2.8​% for this novel system. PFDP-​b-​P3HT is also employed as an additive to P3HT:PCBM bulk heterojunction devices and demonstrates increases from 3.6​% to 4.2​%, and remarkably gives a stable flat-​line efficiency over the time studied

Fullerene-capped copolymers for bulk heterojunctions: device stability and efficiency improvements

A fullerene end-capped polymer-compatibilizer based on poly(3-hexylthiophene) (P3HT) was synthesized and demonstrated to have a remarkable effect on both the stability and efficiency of devices made from exemplar P3HT and [6,6]-phenyl C-61-butyric acid methyl ester (PCBM). P3HT with ethynyl chain-ends and alpha-azido-omega-bromo-PS were prepared via Grignard metathesis (GRIM) and atom transfer radical polymerisation, respectively. "Click" chemistry resulted in the preparation of poly(3-hexylthiophene)block- omega-bromo-polystyrene (P3HT-b-PS-Br), and subsequent atom transfer radical addition chemistry with fullerene (C-60) yielded the donor-acceptor block copolymer P3HT-b-PS-C-60. Both P3HT-b-PS-Br and P3HT-b-PS-C-60 were considered as compatibilizers with P3HT/PCBM blends, with the study detailing effects on active-layer morphology, device efficiency and stability. When used at low concentrations, both P3HT-b-PS-Br (1%) and P3HT-b-PS-C-60 (0.5%) resulted in considerable 28% and 35% increases in efficiencies with respect to devices made from P3HT/PCBM alone. Furthermore, P3HT-b-PS-C-60 (0.5%) resulted in an important improvement in device stability

«Synthesis of bio-based polymers starting from bio-sourced divinylglycol»

National audienc

Inhibition and exaltation of emission in layer-controlled colloidal photonic architectures

We described the engineering and characterization of photonic colloidal crystals based on silica spheres with incorporated YVO4:Eu luminescent nanoparticles. These structures exhibit strong angle-dependent luminescent properties. The controlled incorporation of a planar defect in the periodic structures gives rise to the creation of a pass band in the pseudo-gap. In the energy range of this pass band,weobserved a strong increase in combination with a sharp width of the emission spectrum, which opens new possibilities for the design of low-threshold and/or single mode photonic crystal lasers

Epoxidized rosin acids as co-precursors for epoxy resins

A series of novel epoxy resins were prepared from chemically modified rosin, mainly constituted of abietic acid, diglycidyl ether of bisphenol-A (DGEBA) in different percentages as co-reactants, and isophorone diamine as cross-linking agent. Reactive epoxide groups were introduced in the structure of this common pine tree derivative. The chemical structures of various epoxidized rosin acids precursors were confirmed by NMR spectroscopy. Differential scanning calorimetry and dynamic mechanical analysis were used to determine the glass transition temperature and the elastic modulus of the cured epoxy resins. Relatively rigid materials with thermo-mechanical properties depending on the structure of rosin acid derivatives and their ratios with DGEBA were obtained. Epoxy precursors based on renewable rosin can be efficiently used as co-additives of DGEBA for epoxy products