1,721,073 research outputs found
Renewable polymers and plastics: performance beyond the green
Full text linkRenewable bio-based polymers are one of the effective answers that the bioeconomy offers
to solve the environmental emergency connected to plastics and more specifically fossilbased
plastics. Previous studies have shown that more than 70% of the natural capital cost
associated with plastic derives from the extraction and processing of fossil raw materials
and that the price of fossil plastic would be on average 44% higher if such impact was fully
paid by businesses. The disclosure of the hidden costs of plastics will contribute to dispelling
the myth of the expensiveness of renewable polymers. Nevertheless, the adoption of biobased
plastics in the market must be motivated by their functional properties and not merely
by their green credentials. This article highlights some successful examples of synergies
between chemistry and biotechnology in achieving a new generation of bio-based
monomers and polymers. Their success is justified by the combination of scientific advances
with positive environmental and social fallout
Biocatalysis: Sustainable solutions for the synthesis and depolymerization of aromatic–aliphatic polymers
No full textEnvironmentally Friendly Synthesis of Cardanol-Based Polyesters and Their Application as Poly(lactic acid) Additives
No full textByproducts derived from the food industry are an interesting biomass to valorize as they are cheap to source, their generation does not compete with food and feed production, and their utilization solves the waste disposal issue. In this work, we
focused on the production of a series of polyesters using a cardanol-derived diol produced from the inedible shell of cashew nuts.
The synthesized polymers are 100% biobased since the diacid components of the structure (adipic acid and succinic acid) can also
be bio-derived monomers. Moreover, the overall process is a paradigm for a green circular economy as the synthesis was conducted via mild enzymatic catalysis (T < 90 °C) in a solventless system. The final workup procedure to recover the materials was conducted using the biomass-derived solvent methyl-tetrahydrofuran, therefore presenting a methodology that does not include any petroleumbased component. This work led to the biocatalyzed synthesis of linear cardanol-based polyesters having mean average molecular
weights between 1800 and 4100 g mol−1 and low dispersity values (2 < D̵), which were used to plasticize poly(lactic acid), leading to an increase in the elongation at break of the resulting ble
Chemo‐enzymatic derivatization of glycerol‐based oligomers: structural elucidation and potential applications
No full text: Switching from oil-based to bio-based feedstocks to ensure the green transition to a sustainable and circular future is one of the most pressing challenges faced by many industries worldwide. For the cosmetics and personal and house care industries there is a strong drive to accelerate this transition from the customers that starts favoring the purchase of naturally derived and bio-degradable products over the traditionally available products. In this work we developed a series of fully biobased macromolecules constituted of a glycerol-based oligoester backbone. Based on the subsequent derivatization with fatty acids or peptides, the resulting products may find application as emulsifiers, wetting agents, and potential vectors for the delivery of bioactive peptides. All steps of the resulting macromolecules were conducted following the green chemistry principles with no toxic or environmentally damaging compounds that were used in the overall production process
ENZYMATIC CATALYSIS FOR POLYCONDENSATION: POTENTIAL IMPACT AND TECHNOLOGICAL BARRIERS
No full textENZYMATIC CATALYSIS FOR POLYCONDENSATION:
POTENTIAL IMPACT AND TECHNOLOGICAL BARRIERS
Alessandro Pellis1, Livia Corici2, Valerio Ferrario1, Cynthia Ebert1 and Lucia Gardossi1*
1Dipartimento di Scienze Chimiche e Farmaceutiche, Università degli Studi di Trieste, Piazzale Europa 1, 34127 Trieste, Italy
2SPRIN S.p.A., via Flavia 23/1, 34148 Trieste, Italy
e-mail: [email protected]
1.Introduction
The extraordinary catalytic potential of enzymes and lipases in particular in polyesters synthesis has been reported in the last two decades.[1] Enzymes are selective bio-catalysts that enable the minimization of protection/deprotection strategies so that monomers with functionalities can be used while avoiding branching. The benefits coming from the use of enzymes in polycondensation reactions are also related to their sustainability and high efficiency at mild conditions: toxic metal catalysts can be avoided and processes can be carried out at temperatures below 80°C. Although the Mn of products attainable by enzymatic polycondensation is in most cases below 10.000, the technology can be used in the production of pre-polymers or in combination with chemical or thermal polymerization. Thanks to the mild reaction conditions, the enzymatic approach to polycondensation is complementary to the chemical synthesis providing a route for the introduction of functional groups inside the polymeric chain with the aim of production of “reactive” polyesters. However, the wide array of enzymatic polyester synthesis described in the scientific literature at laboratory scale are currently not exploited at industrial scale, especially because of low biocatalyst efficiency under process conditions. Recyclability, stability in the viscous conditions of polymerization process and under stirring are the main problems investigated by the “Laboratory of Applied and Computational Biocatalysis” of the University of Trieste. Results achieved in our recent studies will be presented, along with specific enzymatic and synthetic methodologies that can be now used in the enzymatic polycondensation of bio-based polyols and diacids.
2.Results and discussion
The reactions were performed using a robust immobilized enzymes suspended in the monomers, without addition of solvent. A specific immobilization method has been developed for preventing the release of the enzyme during the polycondensation into the polymeric product.[2] Lipase B from Candida antarctica (CALB) was used as biocatalyst
Evolving biocatalysis to meet bioeconomy challenges and opportunities
Full text linkThe unique selectivity of enzymes, along with their remarkable catalytic activity, constitute powerful tools for transforming renewable feedstock and also for adding value to an array of building blocks and monomers produced by the emerging bio-based chemistry sector. Although some relevant biotransformations run at the ton scale demonstrate the success of biocatalysis in industry, there is still a huge untapped potential of catalytic activities available for targeted valorization of new raw materials, such as waste streams and CO2. For decades, the needs of the pharmaceutical and fine chemistry sectors have driven scientific research in the field of biocatalysis. Nowadays, such consolidated advances have the potential to translate into effective innovation for the benefit of bio-based chemistry. However, the new scenario of bioeconomy requires a stringent integration between scientific advances and economics, and environmental as well as technological constraints. Computational methods and tools for effective big-data analysis are expected to boost the use of enzymes for the transformation of a new array of renewable feedstock and, ultimately, to enlarge the scope of biocatalysis
Materials & design / Characterisation of enzyme catalysed hydrolysation stage of poly(lactic acid) fibre surface by nanoscale thermal analysis: new mechanistic insight
No full textEnzyme catalysed hydrolysis of bio-based poly(lactic acid) (PLA) represents an environmentally-friendly route for a controlled modification of polymer fibres. In this work, the topochemical hydrolysis reaction of cutinase from Humicola insolens (HiC) on PLA fibre was mechanistically investigated using the advanced surface sensitive nanoscale thermal analysis (nano-TA) technique. The enzymatic hydrolysis preferentially occurs at the amorphous regions of the fibre outer layer, thus leading to randomised hydrolysis, monomer release and ablation of the fibre surface during the initial phase of the hydrolysis. Due to the higher hydrolysis rate at amorphous regions, the crystallinity of the fibre outer layer increases. As a result, an enrichment in overall fibre crystallinity is observed by increased melting enthalpy. The accessibility of the enzyme to the fibre core is restricted, thus the change in crystallinity is prevalent on the fibre outer region. The observed increase of the surface softening temperature from the glass transition temperature close to the melting on-set of crystalline PLA as detected by nano-TA supports the hypothesis, that selective hydrolysis preferably takes place at the amorphous region at the fibre outer layer, thus leading to modified PLA fibres with an unchanged fibre core and a very thin and highly crystalline surface layer.Version of recor
Solventless polyester synthesis using a recyclable biocatalyst magnetic nanoarchitecture
No full textImproving enzyme activity and stability as well as preserving selectivity is a must for rendering biocatalysis an economically viable technology. These improvements can be achieved by immobilizing the biocatalyst on the surface of metal oxide magnetic nanoparticles. The aim of this work is to rational design Biocatalyst Magnetic Nanoarchitecture (BMN) consisting of spinel iron oxides nanoparticles having optimized morpho structural (i.e., particles size, shape and crystallinity), textural (i.e., high surface area) and magnetic properties. Candida antarctica lipase B (CaLB) was immobilized on the nanoparticles' surface investigating the optimal bioconjugation conditions and performing the biochemical characterizations to quantify protein concentration and to assess enzymatic activity. Once immobilized on the magnetic nanoparticles surface, CaLB was tested for an enzymatic polycondensation reaction to synthesize polyesters starting from renewable monomers such as the dimethyl ester of adipic acid and 1,8-octanediol. Conversion of monomers was >87% over three reaction cycles while the number average molecular weights of the products were between 4200 and 5600 Da with a dispersity <2. Efficient recycling of the enzyme upon magnetic separation was demonstrated for three reaction cycles
Biodegradable and gas barrier polylactic acid/star-shaped polycaprolactone blend films functionalized with a bio-sourced polyelectrolyte coating
No full textThis work aims at improving and disclosing new properties of films based on polylactic acid (PLA) and a starshaped
polycaprolactone (PCL). Indeed, previous works demonstrated that the presence of ad-hoc synthesized
PCL, characterized by low molecular weight and carboxyl end groups (coded as PCL-COOH), improves the
elongation at break of the films compared to that of neat PLA and increases their functionality. To further
improve the properties of the system, alternating layers of chitosan (CH) and DNA were deposited on the surface
applying a Layer-by-Layer (LbL) technique. This method was chosen because it allows the properties of the
system to be modified without affecting the specific features of the bulk. In addition, the LbL technique is easily
scalable and environmentally friendly because it is based on the use of an aqueous solution of two biomaterials,
namely DNA and CH, which are not only derived from renewable sources but are also biocompatible and
biodegradable. IR measurements on model silicon substrates subjected to the same treatment as the films,
pointed out a linear growth of the proposed LbL assembly. Indeed, FE-SEM measurements highlighted the
deposition of a uniform coating. The presence of the CH/DNA assembly reduced the oxygen permeability under
both dry and humid (50% R.H.) conditions when compared to the uncoated film. In addition, the coating had no
relevant effect on the hydrolytic and enzymatic degradation of the system, so that the biodegradability of the film
was maintained
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