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With the production of wood waste constantly on the increase, questions relating to its recycling and reuse are becoming unavoidable. The reuse of wood and its derivatives can be achieved through the production of composite materials, using wood as a reinforcement or even as the main matrix of the material. Additive manufacturing (also known as 3D printing) is an emerging and very promising process, particularly with the use of bio-based and renewable materials such as wood or its industrial derivatives. The aim of this paper is to present an overview of additive manufacturing processes using wood as a raw material and including industrial solutions. After presenting wood and its waste products, all the additive manufacturing processes using wood or its industrial derivatives will be presented. Finally, for each 3D printing process, this review will consider the current state of research, the industrial solutions that may exist, as well as the main challenges and issues that still need to be overcome. [ABSTRACT FROM AUTHOR]

The high volume of plastic waste and the extremely low recycling rate have created a serious challenge worldwide. Local distributed recycling and additive manufacturing (DRAM) offers a solution by economically incentivizing local recycling. One DRAM technology capable of processing large quantities of plastic waste is fused granular fabrication, where solid shredded plastic waste can be reused directly as 3D printing feedstock. This study presents an experimental assessment of multi‐material recycling printability using two of the most common thermoplastics in the beverage industry, polyethylene terephthalate (PET) and high‐density polyethylene (HDPE), and the feasibility of mixing PET and HDPE to be used as a feedstock material for large‐scale 3‐D printing. After the material collection, shredding, and cleaning, the characterization and optimization of parameters for 3D printing were performed. Results showed the feasibility of printing a large object from rPET/rHDPE flakes, reducing production costs by up to 88%. Highlights: Study: multi‐material recycling printability of PET‐HDPE.Large‐scale fused particle‐based 3‐D printing technically possible.Direct waste 3‐D printing rPET/rHDPE flakes, reducing production costs up to 88%. [ABSTRACT FROM AUTHOR]

In this study, the degradation mechanism and tensile properties of plasticized poly(D,L-lactide-co-glycolide) (PLGA) are evaluated. Purasorb PDLG 5010 is first extruded into rods with or without plasticizers, i.e, D,L-lactide or aspirin. Then, the hydrolytic degradation of such rods is studied in phosphate buffer solution. A very fast hydrolytic degradation (half-life time lower than 1 month) that is enhanced by the presence of plasticizer occurs through a heterogeneous mechanism and leads to the formation of hollow rods. The mechanical properties of these rods are studied in dry and wet states. Finally, water diffusivity in plasticized (or not) PLGA is estimated. [ABSTRACT FROM AUTHOR]

Atom Transfer Radical Polymerization (ATRP) and Ring-Opening Polymerization (ROP) were combined to synthesize diblock environmental friendly poly(ϵ-caprolactone)-block-poly(methyl ether diethylene glycol methacrylate) (PCL- b -PMEO 2 MA) through a sequential two-step strategy. These PCL- b -PMEO 2 MA copolymers were produced using 2-hydroxyethyl-2-bromoisobutyrate as bifunctional initiator. In the first step, ϵ-caprolactone was initiated by the hydroxyl group of this particular initiator. Tin octoate, zinc triflate and bismuth triflate were tested as non-toxic catalysts to obtain α-bromide–ω-hydroxy bifunctional PCL macroinitiator. Secondly, the controlled ATRP of MEO 2 MA was tuned from the same bifunctional initiator. Finally, PCL- b -PMEO 2 MA were produced by carrying out ATRP of MEO 2 MA from PCL macroinitiator. Preliminary data on self-assembly of such thermo-sensitive PCL- b -PMEO 2 MA in aqueous phase are given. [ABSTRACT FROM AUTHOR]

ABSTRACT Polymers containing o-nitrobenzyl esters are promising for preparation of light sensitive materials. o-Nitrobenzyl methacrylate has already been polymerized by controlled ATRP or RAFT. Unfortunately, the radical polymerization of o-nitrobenzyl acrylate (NBA) was not controlled until now due to inhibition and retardation effects coming from the nitro-aromatic groups. Recent developments in the Single Electron Transfer-Living Radical Polymerization (SET-LRP) provide us an access to control this NBA polymerization and living character of this NBA SET-LRP is demonstrated. Effects of CuBr2 and ligand concentrations, as well as Cu(0) wire length on SET-LRP kinetics are shown presently. A first-order kinetics with respect to the NBA concentration is observed after one induction period. SET-LRP proceeds with a linear evolution of molecular weight and a narrow distribution. High initiation efficiency close to 1 and high chain-end functionality (∼93%) are reached. Chain extension of poly( o-nitrobenzyl acrylate) is realized with methyl acrylate (MA) to obtain well defined poly( o-nitrobenzyl acrylate)-b-poly(methyl acrylate) (PNBA- b-PMA). Finally, light-sensitive properties of PNBA are checked upon UV irradiation. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 2192-2201 [ABSTRACT FROM AUTHOR]

ABSTRACT Poly( d,l-lactide- co-glycolide) (PLGA) copolyesters are commonly used in biomedical applications. Researches were carried out on nontoxic or low-toxic catalysts that are enough efficient to provide short polymerization times, adequate microstructure chains and similar properties than the commercial PLGA materials. In this study, PLGA were synthesized by ring-opening copolymerization (ROP) using three different catalysts. Stannous octoate is the first catalyst we used, as it is very efficient, even its toxicity is still on debate. Two others low-toxic catalysts [zinc lactate and bismuth subsalicylate (BiSS)] were also evaluated. The comparison of these ROP was realized in terms of kinetics and control of the polymerization. Then, the influence of the catalyst on the PLGA microstructure chains is reported. Finally, abiotic hydrolytic degradation rate is studied. Results described in this article show that BiSS is one very attractive catalyst to produce low toxic PLGA for biomedical applications. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 1130-1138 [ABSTRACT FROM AUTHOR]

ABSTRACT A cholesterol-based liquid crystal monomer, diethylene glycol cholesteryl ether acrylate (DEGCholA), has been successfully polymerized by atom transfer radical polymerization (ATRP) for the first time. Appropriate experimental conditions to control the polymerization of DEGCholA have been investigated using a model initiator (ethyl 2-bromoisobutyrate) in tetrahydrofuran (THF) or toluene at 60 °C. Well-controlled ATRP of DEGCholA was obtained using N, N, N′, N′, N″-pentamethyldiethylenetriamine as ligand in THF at 60 °C. These conditions were then applied to initiate the ATRP of DEGCholA from multifunctional macroinitiators based on dextran. Using a protection/deprotection synthetic scheme, novel graft glycopolymers (Dex- g-PDEGCholA) have been synthesized. The mesomorphic properties of DEGCholA, PDEGCholA, and Dex- g-PDEGCholA have been studied by thermal polarizing optical microscopy, differential scanning calorimetry, and X-ray scattering. PDEGCholA and Dex- g-PDEGCholA show an interdigitated smectic A phase (SmAd) between Tg (∼30 °C) and around 170 °C. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 3829-3839 [ABSTRACT FROM AUTHOR]

The synthesis of amphiphilic dextran- g-poly(methyl methacrylate) glycopolymers (Dex- g-PMMA) is studied using 'grafting from' concept and atom transfer radical polymerization. Two strategies have been examined to control the macromolecular parameters of such glycopolymers. One is involving four steps including a protection/deprotection approach and the second one only two steps. The introduction of initiators group onto a protected acetylated dextran (and directly onto dextran) was achieved resulting in protected DexAcBr (and in unprotected DexBr). These two types of polysaccharidic macroinitiators differ in term of solubility (hydrophilic DexBr vs. hydrophobic DexAcBr) and of position of the initiators groups on the glucosidic units (which are the sites of the future grafts). When evaluated as macroinitiators for ATRP of MMA, control was achieved in both cases but DexBr gave much faster polymerization and lower average grafting efficiency compared with DexAcBr or model initiator. Advantages and drawbacks of both pathways have finally been discussed. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010 [ABSTRACT FROM AUTHOR]

The article presents a study which discusses adhesion and colonization of mesenchymal stem cells on polylactide or PLCL fibers dedicated for tissue engineering. Topics discussed include use of porcine mesenchymal stem cells (MSC) in the study, cultivation and cell adhesion of mesenchymal stem cells, and cultivation of MSC on various polymers such as polymers made with lactic acid or caprolactone.

Among all photosensitive monomers reported in the literature, o -nitrobenzyl acrylate (NBA) was selected in this present study. Two strategies were compared to produce azido-terminated poly( o -nitrobenzyl acrylate) (PNBA) using controlled Single Electron Transfer-Living Radical Polymerization (SET-LRP). In a parallel way, dextran (Dex) was modified by the introduction of several alkynyl-terminated hydrophobic chains. Finally, an Huisgen-type Copper (I)-catalyzed Azide–Alkyne Cycloaddition (CuAAC) click-chemistry was carried out to produce amphiphilic Dex- g -PNBA glycopolymers with different number and length of PNBA grafts. 2D DOSY 1 H NMR was used to prove the formation of such glycopolymers. Preliminary study on Dex- g -PNBA self-assembly was done by measuring the critical water content (CWC) above which Dex- g -PNBA started to auto-organize themselves to produce nano-objects. Finally, under UV irradiation, PNBA grafts turn into poly(acrylic acid) ones giving light-sensitive properties to such amphiphilic Dex- g -PNBA. Such properties were evaluated and compared with those of PNBA. [ABSTRACT FROM AUTHOR]

Abstract: Aliphatic hydrocarbon oil-in-water nanoemulsions were prepared using mixtures of an amphiphilic nonionic polysaccharide (dextran modified by covalent attachment of hydrocarbon tails) and tetraethylene glycol dodecylether as stabilizers. Nanoemulsions stabilized by amphiphilic polysaccharide alone underwent Ostwald ripening. On the contrary, nanoemulsions prepared with certain mixtures of hydrophobically modified dextran and tetraethylene glycol dodecylether exhibited no significant variation of their average droplet diameter over a period of time that depended strongly on the nature of the dispersed oil. When changing from n-hexane to n-octane and n-dodecane, the period of complete inhibition of Ostwald ripening varied from 3h to several months. Polymer–surfactant interactions and co-adsorption at oil/water interface were demonstrated by dynamic interfacial tension measurements and dilational surface rheology. [Copyright &y& Elsevier]

PLA nanoparticles loaded with n -alkyl gallates (AGs) were prepared either by nanoprecipitation (NP) or by O/W emulsion/solvent evaporation (E/SE). A nonionic hydrophobically modified polysaccharide was used for surface coverage and for ensuring colloidal stability. Different parameters were systematically assessed to enhance the drug incorporation, with the aim of obtaining monomodal and narrow particle size distributions. The nanoparticles were characterized by 1 H NMR, transmission electron microscopy (TEM) and laser light scattering granulometry. The colloidal stability of suspensions was evaluated after incubation in NaCl solutions and was maintained up to 1 M NaCl. The mean particle diameter and the width of size distribution were found very similar for both processes (slightly lower diameters when using E/SE) with various drug loadings. The amount of encapsulated AG by E/SE was about twice that encapsulated by NP. The in-vitro release of AG was evaluated under sink conditions and no burst effect was observed. Release curves were successfully modeled using the Fick diffusion model with a constant diffusion coefficient and assuming non-swellable particles. Diffusion coefficients of AG loaded in nanoparticles prepared by NP were higher than those found in nanoparticles elaborated by E/SE. [ABSTRACT FROM AUTHOR]