The synthesis and characterization of novel block copolymers derived from delta-tetradecalactone (TDL), a biobased lactone, and lactide (LA), using ring-opening polymerization, was investigated. Poly(delta-tetradecalactone) (PTDL) macroinitiators were first prepared in bulk via organocatalysis using TBD and subsequently employed as macroinitiators to generate a range of diblock copolymers with poly(l-lactide) or poly(d,l-lactide) segments. These copolymers exhibit tunable thermal properties and demonstrate the ability to self-assemble in nonpolar media such as isododecane, with particle formation behavior dependent on the copolymer composition and the preparation method (direct solubilization or nanoprecipitation). The biodegradability of the materials was evaluated under OECD 301F conditions. While copolymers with long PLA blocks showed limited biodegradation, incorporation of short lactide blocks maintained significant biodegradation levels, particularly when aided by a bioavailability improvement method (2,2,4,4,6,8,8-heptamethylnonane, HMN).

Protein immobilization on solid surfaces is a prevalent strategy in biotechnology and industry, offering advantages in terms of stability and reusability. Various methods, including covalent attachment, adsorption, covalent cross-linking, and entrapment, have been developed, with challenges in adapting these techniques to enzymes due to their catalytic pockets. In a previous study, we introduced a method for grafting the glycoside hydrolase Neocallimastix patriciarum endo-(3-1,4-xylanase (NpXyn11A) onto paramagnetic beads, preserving its biological activity. Here, we extend this approach to polymeric surfaces, specifically polyisoprene (PI) and polydimethylsiloxane (PDMS), known for their elasticity. The surfaces are plasma-activated and functionalized with maleimide functions to immobilize the engineered protein Jo through a one-point thiol-maleimide click reaction. In a second step, the xylanase fused to the protein In is immobilized on the membrane by a spontaneous and specific covalent bond between Jo and In. A custom device is employed to stretch the elastomer surfaces, altering the distance between immobilized enzymes. The specific activity of the immobilized xylanase, evaluated with a chromogenic substrate, mirrors that of the free enzyme in solution. However, the use of natural polysaccharides reveals activity variations based on the extent of surface stretching, providing insights into the impact of spatial proximity on enzyme dynamics. Our study contributes to overcoming limitations in traditional enzyme immobilization, offering valuable insights into the dynamics of multi-enzymatic complexes.

This short review explores the enzymatic treatment of lignin in alkaline homogeneous systems, focusing on alkaliphilic laccases. In acidic conditions, native laccases are known to promote lignin polymerization, while the addition of mediators enables depolymerization into valuable small molecules. Alkaliphilic laccases, which remain active in basic pH where the vast majority of industrial lignins are soluble, present an interesting alternative. However, the literature shows varied outcomes - polymerization, depolymerization, or both processes - making it difficult to draw clear trends. This review aims to summarize the current state of the art of the enzymatic treatment of lignin in alkaline conditions.

Enzymatic modification of Kraft lignin under alkaline conditions was investigated using bilirubin oxidase (BOD) in borate buffer (pH 10). Control solubilization without enzyme addition revealed a notable increase in molar mass (up to 1.7-fold) and potential borate complexation with lignin hydroxyl groups, as evidenced by thermogravimetric and 11B NMR analyses. BOD treatments induced substantial polymerization, with molar mass increases of up to 4-fold for insoluble fractions after 24 h, while soluble fractions exhibited progressive increases over 5 days. Quantitative 31P NMR showed reductions in aliphatic and phenolic hydroxyl groups by 20%, suggesting oxidative coupling reactions, particularly through 4-O-5′ and 5-5′ linkages. Solid-state 13C NMR confirmed structural changes associated with polymerization. Dynamic light scattering (DLS) indicated the presence of colloidal aggregates, potentially explaining challenges in HSQC NMR signal acquisition. These findings highlight the efficacy of bilirubin oxidase in catalyzing lignin polymerization and underscore the structural impact of borate–lignin interactions in alkaline media, paving the way for advanced lignin valorization strategies.

Searching for biobased and biodegradable polymers, we explored the organocatalytic ring-opening polymerization (ROP) of a renewable n-alkyl delta-lactone, namely delta-tetradecalactone (delta-TDL) that can be extracted from coconut oil, and we studied the ready biodegradability of the corresponding polyester. As reported for other n-alkyl delta-lactones, 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) was used to perform the bulk and room temperature ROP of delta-TDL. A study of the purification of the monomer prior to its ROP showed the importance of the combination of a distillation process and an elution through basic alumina to remove most of the impurities and obtain the higher molar masses. Despite this careful purification, capped molar masses were obtained (<40 kg/mol) and attributed by NMR and MALDI-ToF spectroscopy to TBD initiation and other side-initiators contained in the monomer, which were not possible to be identified. Other catalysts such as diphenyl phosphate (DPP) and the phosphazene superbase t-BuP4 combined with a thiourea were also tried. The assessment of poly(delta-tetradecalactone) (pTDL) ready biodegradability was finally performed using the OECD test guideline 301F and showed the obtention of up to 41 % biodegradation rate in 28 days using a bioavailability improvement method.

Among the polymer families, aliphatic polyesters stand out from this category thanks to their degradable and biocompatible properties. In particular, the gamma-lactones differ from other lactones by yielding polyesters that can be depolymerized back to the monomer and offer the advantage of counting various biobased monomers. As an example, alpha-hydroxy- gamma-butyrolactone (HBL) is a hydroxy-functionalized monomer that can be obtained by a biological synthetic route from glucose. In this article, the ring-opening copolymerization (ROCP) of HBL and L-lactide (LLA) using t-BuP4 as catalyst is investigated. The copolymerizations were conducted within a temperature range of 5-100 degrees C, affording monomer conversions exceeding 80%. The characterization of the copolyesters revealed a branched structure consisting of different HBL patterns, including cyclic, linear, and branched motives. Performing a kinetic study of the copolymerization at room temperature provided a deeper understanding of the mechanism. By modulating the reaction parameters, copolymers of low molar masses with an HBL content of up to 33% were synthesized. High molar mass LLA/HBL-based copolyesters, with Mw up to 290,000 g/mol, were synthesized by a straightforward chain coupling reaction with a diisocyanate.

This review aims at answering the following question: how can a researcher be sure to succeed in grafting a protein onto a polymer surface? Even if protein immobilization on solid supports has been used industrially for a long time, hence enabling natural enzymes to serve as a powerful tool, emergence of new supports such as polymeric surfaces for the development of so-called intelligent materials requires new approaches. In this review, we introduce the challenges in grafting protein on synthetic polymers, mainly because compared to hard surfaces, polymers may be sensitive to various aqueous media, depending on the pH or reductive molecules, or may exhibit state transitions with temperature. Then, the specificity of grafting on synthetic polymers due to difference of chemical functions availability or difference of physical properties are summarized. We present next the various available routes to covalently bond the protein onto the polymeric substrates considering the functional groups coming from the monomers used during polymerization reaction or post-modification of the surfaces. We also focus our review on a major concern of grafting protein, which is avoiding the potential loss of function of the immobilized protein. Meanwhile, this review considers the different methods of characterization used to determine the grafting efficiency but also the behavior of enzymes once grafted. We finally dedicate the last part of this review to industrial application and future prospective, considering the sustainable processes based on green chemistry.

Organocatalysis has been widely developed over the past decades as an alternative to metal-based catalysis. The actual concerns have also promoted the development of sustainable and degradable polymers. In this context, gamma-lactones are an interesting class of monomers that count many bio-based monomers, yielding polyesters that can be readily depolymerized. Also, the use of functional substituted lactones such as the alpha-hydroxy-gamma-butyrolactone (HBL) affords polyesters with pendant groups offering possible postmodification reactions. This article focuses on the ring-opening copolymerization (ROCP) of alpha-hydroxy-gamma-butyrolactone (HBL) and epsilon-caprolactone (epsilon-CL) in the presence of phosphazene P-4 base (tert-BuP4) as catalyst. The bulk copolymerization at high temperature (80 degrees C) yielded fast kinetics (5 min) and high monomer conversions (98% for epsilon-CL; 88% for HBL) and molar masses (14900 g/mol with (sic) = 3.8). A kinetics study at 80 degrees C revealed a partial HBL depolymerization over time. This phenomenon induced changes in the microstructures of the copolymers. Similar high conversions and molar masses could be also achieved at room temperature for 6 h without any depolymerization. Various monomer feed ratios were also evaluated affording copolyesters with up to 31% of incorporated HBL. In addition, DFT calculations with respect to the HBL homopolymerization revealed similar activation energies between different possible reactions, which include ring-opening polymerization, branching, and backbiting reactions.

According to the fatty acid and headgroup compositions of the phospholipids (PL) from Hevea brasiliensis latex, three synthetic PL were selected (i.e. POPA: 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphate POPC: 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine and POPG: 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoglycerol) to investigate the effect of PL headgroup on the interactions with two major proteins of Hevea latex, i.e. Rubber Elongation Factor (REF1) and Small Rubber Particle Protein (SRPP1). Protein/lipid interactions were screened using two models (lipid vesicles in solution or lipid monolayers at air/liquid interface). Calcein leakage, surface pressure, ellipsometry, microscopy and spectroscopy revealed that both REF1 and SRPP1 displayed stronger interactions with anionic POPA and POPG, as compared to zwitterionic POPC. A particular behavior of REF1 was observed when interacting with POPA monolayers (i.e. aggregation + modification of secondary structure from α-helices to β-sheets, characteristic of its amyloid aggregated form), which might be involved in the irreversible coagulation mechanism of Hevea rubber particles.

One-step sequence-selective block copolymerization requires stringent catalytic control of monomers relative activity and enchainment order. It has been especially rare for A(n)B(m)-type block copolymers from simple binary monomer mixtures. Here, ethylene oxide (EO) and N-sulfonyl aziridine (Az) compose a valid pair provided with a bicomponent metal-free catalyst. Optimal Lewis acid/base ratio allows the two monomers to strictly block-copolymerize in a reverse order (EO-first) as compared with the conventional anionic route (Az-first). Livingness of the copolymerization facilitates one-pot synthesis of multiblock copolymers by addition of mixed monomers in batches. Calculation results reveal that a Janus effect of Lewis acid on the two monomers is key to enlarge the activity difference and reverse the enchainment order.

Substituted δ-lactones are mostly biobased monomers with unfavorable to intermediate thermodynamic parameters. Nevertheless, they can lead to the synthesis of (co)polyesters by ring-opening (co)polymerization mediated by either organocatalysis or metal-based catalysis.

The growing awareness of environmental concerns and the fossil resources depletion have raised the need to develop sustainable and degradable polymers such as aliphatic polyesters. gamma-Lactone-based polyesters are of great interest today due to their ability to depolymerize. The introduction of functional groups appeared also useful to tune the properties of such polyesters. This can be addressed by the use of functional monomers such as the sugar-based alpha-hydroxy-gamma-butyrolactone (HBL). In this study, the synthesis of random copolyesters of HBL and e-caprolactone (e-CL) was investigated via ring-opening copolymerization in the presence of La[N(SiMe3)2]3 as a catalyst. High polymerization temperature (80 degrees C) was required for fast and high monomer conversions. The characterization of the copolyesters and kinetic investigations provided better insight into the polymerization mechanism and formation of various HBL monomer units (cyclic, linear and branched). La[N(SiMe3)2]3 catalyst afforded high HBL conversion ratio (over 85 %) for the copolymerization reaction enabling the synthesis of copolyesters with a ratio of HBL units ranging from 9 to 63 %.

Developing new biomaterials is an active research area owing to their applications in regenerative medicine, tissue engineering and drug delivery. Elastin-like polypeptides (ELPs) are good candidates for these applications because they are biosourced, biocompatible and biodegradable. With the aim of developing ELP-based micelles for drug delivery applications we have synthesized 15 acyl-ELP compounds by conjugating myristic, palmitic, stearic, oleic or linoleic acid to the N-terminus of three ELPs differing in molar mass. The ELP-fatty acid conjugates have interesting solution behavior. They form micelles at low temperatures and aggregate above the cloud point temperature (Tcp). The critical micelle concentration depends on the fatty acid nature while the micelle size is mainly determined by the ELP block length. We were able to show that ELPs were better hydrated in the micelles than in their individual state in solution. The micelles are stable in phosphate-buffered saline at temperatures below the Tcp, which can vary between 20 °C and 38 °C depending on the length or hydrophilicity of the ELP. Acyl-ELP micelles were loaded with the small hydrophobic molecule Nile red. The encapsulation efficiency and release kinetics showed that the best loading conditions were achieved with the largest ELP conjugated to stearic acid.

To obtain and maintain rubber properties such as elasticity, strength, creep, and chemical resistance, or stiffness over time, rubbers must be chemically cross-linked, mainly by sulfur vulcanization. However, the materials produced in this manner result in irreversibly cross-linked networks and are consequently difficult to recycle, which leads to large quantities of rubber waste each year. In this paper, a new route to synthesize reversibly cross-linked 1,4-cis-polyisoprene (PI) and -polybutadiene (PB) based on the Diels-Alder chemistry is investigated. Furan groups are first grafted along the polymeric backbone and at chain ends. In a second step, a bis-maleimide compound is added to the modified liquid material, leading to the formation of a thermo-reversible cross-linked elastomer. Mechanical properties of the resulting rubber can be easily tuned and depend on the bis-maleimide/furan ratio as well as on the nature of the polymeric precursor (polyisoprene vs polybutadiene). The good reprocessability of these materials was demonstrated by remolding them five times without any loss of properties between the first and the last cycle.

Developing new biomaterials is an active research area owing to their applications in regenerative medicine, tissue engineering and drug delivery.

Triggered by raised environmental awareness and the rising requirements for sustainable polymers such as degradable or recyclable polymers, studies on ring-opening (co)polymerization (ROP/ROCP) of (bio-based) cyclic monomers (e.g., cyclic esters, lactides, epoxides etc.) have been booming in recent years. Renewable five-membered γ-butyrolactone (γBL) and derivatives would thus be a desirable feedstock to produce poly(γ-butyrolactone) (PγBL) and different (bio-based) functional polyesters. Their copolymerization with other cyclic monomers could also afford an alternative to tune the properties of the resulting materials. Although γBL was traditionally regarded “non-polymerizable”, some progresses were made recently concerning the ROP/ROCP of γBL and derivatives. More importantly, some polyesters could be totally depolymerized back to their monomers by thermal or chemical treatment. This review is specially focused on ROP of γ-lactones and their copolymerization with other cyclic monomers by different catalytic/initiating systems, including Lewis/Brønsted acids, organic bases and alkali metal compounds, organometallic compounds, and cooperative bicomponent catalytic systems. The depolymerization process of some obtained polyesters is also discussed.

Enzymatic synthesis of fatty acid glucose esters from different fatty acyl donors are performed via enzymatic catalysis in the presence of Candida antarctica lipase B (CALB), using acetonitrile as the solvent. The acyl donor nature (fatty acid or fatty acid vinyl ester) and structure are varied. Lower reaction rates and lower conversions are obtained with fatty acids in comparison to their corresponding vinyl esters. Moreover, the acyl donor with the longest chain length gives the highest conversions. The presence of unsaturation on the acyl donor chain is also shown to be detrimental to the conversion. Practical Applications: The practical applications of the present work are related to the production of gluco-esters that could be used as nonionic surfactants as detergents, cosmetics and food emulsifiers, emollients or conservatives, respectively. In this study, it is shown that in order to get high production yields, each reaction parameter has to be tuned properly.

Propylene oxide (PO) is polymerized by metal-free ring-opening polymerization (ROP) at 25 degrees C using N-heterocyclic carbenes (NHCs) and triethylborane (Et3B) as a bicomponent catalytic system. Poly(propylene oxide)s with predictable molar mass up to 60 000 g.mol(-1) and low dispersity (D<1.10) were obtained without the occurrence of undesirable transfer reaction to the monomer. In presence of an alcohol as the initiator, the ROP of PO follows an anionic mechanism assisted by monomer activation improving the efficiency of NHCs for the polymerization of substituted epoxides. Et3B is involved both in the formation of a complexed active center and in the activation of PO. Interestingly, dihydroxytelechelic PPOs can be readily synthesized not only using 1,4-benzenedimethanol but also water, both serving as difunctional initiators. Block copolyethers are also prepared by PPO chain extension experiments. All (co)polyethers have been thoroughly characterized by H-1 NMR spectroscopy, SEC and MALDI-TOF mass spectrometry as means to elucidate the reaction mechanisms involved in this chemistry.