Polyacrylates Derived from Biobased Ethyl Lactate Solvent via SET-LRP

The precise synthesis of polymers derived from alkyl lactate ester acrylates is reported for the first time. Kinetic experiments were conducted to demonstrate that Cu(0) wire-catalyzed single electron transfer-living radical polymerization (SET-LRP) in alcohols at 25 °C provides a green methodology for the LRP of this forgotten class of biobased monomers. The acrylic derivative of ethyl lactate (EL) solvent and homologous structures with methyl and n-butyl ester were polymerized with excellent control over molecular weight, molecular weight distribution, and chain-end functionality. Kinetics plots in conventional alcohols such as ethanol and methanol were first order in the monomer, with molecular weight increasing linearly with conversion. However, aqueous EL mixtures were found to be more suitable than pure EL to mediate the SET-LRP process. The near-quantitative monomer conversion and high bromine chain-end functionality, demonstrated by matrix-assisted laser desorption ionization time-of-flight analysis, further allowed the preparation of innovative biobased block copolymers containing rubbery poly(ethyl lactate acrylate) poly(ELA) sequences. For instance, the poly(ELA)-b-poly(glycerol acrylate) block copolymer self-assembled in water to form stable micelles with chiral lactic acid-derived block-forming micellar core as confirmed by the pyrene-probe-based fluorescence technique. Dynamic light scattering and transmission electron microscopy measurements revealed the nanosize spherical morphology for these biobased aggregates

Valorisation of Biowastes for the Production of Green Materials Using Chemical Methods

With crude oil reserves dwindling, the hunt for a sustainable alternative feedstock for fuels and materials for our society continues to expand. The biorefinery concept has enjoyed both a surge in popularity and also vocal opposition to the idea of diverting food-grade land and crops for this purpose. The idea of using the inevitable wastes arising from biomass processing, particularly farming and food production, is, therefore, gaining more attention as the feedstock for the biorefinery. For the three main components of biomass—carbohydrates, lipids, and proteins—there are long-established processes for using some of these by-products. However, the recent advances in chemical technologies are expanding both the feedstocks available for processing and the products that be obtained. Herein, this review presents some of the more recent developments in processing these molecules for green materials, as well as case studies that bring these technologies and materials together into final products for applied usage

Monomers and polymers from plant oils via click chemistry reactions

10.1002/pola.2662

A renewable approach to thermosetting resins

10.1016/j.reactfunctpolym.2012.03.015This is a review of recent developments of thermostable resins derived basically from vegetable oils. Natural vegetable oils have been transformed in polymers following three main routes. The first is the direct polymerization through the double bonds of the fatty acid chain. The cationic copolymerization of soybean oil with styrene, divinylbenzene and different amounts of styrenic monomers containing Si, B and P has been used to produce materials with improved flame retardant properties. The second route is the functionalization of the triglyceride double bonds to introduce readily polymerizable groups: The singlet oxygen photoperoxidation of the allylic positions of high oleic sunflower oil has been used to produce hydroperoxide-containing triglycerides that were dehydrated or reduced to produce respectively enone- and hydroxyl-containing triglycerides. The enone containing derivative has been chemically crosslinked with aromatic diamines through aza-Michael reactions leading to quinoline containing thermosets. The hydroxyl-containing triglycerides have been crosslinked radically prior the introduction of acrylate groups to produce conventional and flame retardant acrylate resins. The third route explored consists of using plant oil-derived chemicals like 10-undecenoic and oleic acids to produce tailor made monomers. Acyclic diene metathesis (ADMET) polymerization has been applied to prepare a set of thermosetting polyesters with flame retardant properties. Moreover thiol-ene 'click' coupling has been used to prepare carboxylic monomers that have been explored to produce thermosetting polyanhydrides for fast drug delivery systems. A set of tailored polyols from the products of coordinative polymerization of the methyl epoxyoleate and the cationic ring opening polymer

Self-Foaming Diphenolic Acid Benzoxazine

10.1016/j.polymer.2012.05.044This work concerns the investigation of porous polybenzoxazines based on the non-toxic renewable diphenolic acid. The approach described relies on the in situ generation of foaming agent (CO2) during the thermal curing. For this purpose, the previously synthesized benzoxazine monomer from diphenolic acid was thermally polymerized at different temperatures. As the beginning of decarboxylation is about 200 °C, we selected five foaming temperatures (Tf) ranging from 190 to 230 °C. The influence of the foaming temperature on the cellular structure and its dependency on final properties is discussed

Polyketoesters from oleic acid. Synthesis and functionalization

10.1039/c3gc41346bIn this study, we exploited the reactivity of the methyl oleate enone derivative for the conversion of this renewable raw material to ketone-containing hydroxyesters. The radical-mediated thiol¿ene addition to the conjugated double bonds has been investigated and low yields were obtained due to secondary reactions. The thiol-Michael addition under acidic and basic/nucleophilic conditions was also examined. While using vanadyl triflate (VO(OTf)2), a slight excess of thiol was necessary to complete the reaction, by using both basic/nucleophilic catalysts 1,5-diazabicyclo[4.3.0]non-5-ene (DBN) and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), quantitative conversion was achieved under stoichiometric conditions in shorter reaction times. The obtained hydroxyester, carrying sulphide and ketone functional groups, was used to obtain polyesters by Novozyme-435 enzymatic polymerization. The coupling between the ketone group of the repeating unit and a model oxyamine has been used to demonstrate the polyketoester functionalization via oxime formation

Anisotropic thermosets from liquid-crystalline azomethynic epoxy resins and primary aromatic diamines

Novel epoxy-terminated monomers based on imine groups were synthesized and their mesogenic properties studied. Aliphatic spacers of different lengths were introduced between the rigid unit and the glycidylic group, and their liquid-crystalline behavior was examined. They were reacted with primary aromatic diamines inside a magnetic field so that the formation of anisotropic networks could be investigated. The influence of curing conditions and the structure of monomers and amines on the formation of liquid-crystal thermosets were investigated. Thermosets with locked nematic textures were obtained in all cases. The influence of a 7.1 T magnetic field on the macroscopic orientation of these materials was studied, and mechanical properties of the resulting networks were evaluated by dynamic mechanical analysis

Flame Retardant High Oleic Sunflower Oil-Based Thermosetting Resins Through Aza- and Phospha-Michael Additions

10.1002/pola.26562A novel phosphorus-containing vegetable oil (PETR) was prepared through phospha-Michael addition of a diphenyl phosphine oxide to the enone derivative of high-oleic sunflower oil (ETR). The reaction was investigated using the enone derivative of methyl oleate under conventional thermal heating and microwave irradiation. The kinetic study showed a great enhancement of reaction rate for the microwave-initiated addition. The crosslinking of ETR with diaminodiphenylmethane (DDM) via aza-Michael addition was also investigated under microwave irradiation, showing a noticeable acceleration of the curing. The new phosphorus-containing triglyceride was crosslinked with DDM to obtain phosphorus-containing vegetable oil-based thermosets of different phosphorus contents. Limiting oxygen index values from 26.4 to 35.0 for the final materials were obtained, demonstrating that the flame retardant properties of vegetable oil-based thermosets can be improved by adding covalently bonded phosphorus to the polyme

Renewable Polybenzoxazines based in Diphenolic Acid

10.1016/j.polymer.2012.02.026The reaction of mixtures of renewable diphenolic acid (DPA) and its methylesterbenzoxazine derivative (MDP-Bz) has been studied. The DPA was introduced to lower the high temperature needed to complete the curing of the pure benzoxazine. In this way, samples with different DPA/MDP-Bz ratio (0, 2, 5, 10 and 25% of DPA) were investigated. Moreover, high performance flame retardant thermosetting resins with phosphorus were prepared through the mixture of MDP-Bz and a DPA-phosphazene derivative (DPA-PPZ). The curing behavior of these materials was studied by differential scanning calorimetry (DSC). Finally, the properties of the materials were evaluated by termogravimetric analysis (TGA), dynamic mechanical analysis (DMTA), tensile measurements, limiting oxygen index (LOI) and UL-94 Burn Test