A lignin-based epoxy/TiO2 hybrid nanoparticle for multifunctional bio-based epoxy with improved mechanical, UV absorption and antibacterial properties.

Lignin, as a natural polymer material, has the advantages of green safety, renewable, and pollution-free. It has a wide application prospect in the field of thermosetting. However, it has been attractive but a huge challenge to design high performance and high added-value lignin-based epoxy resin. Herein, lignin-based epoxy (LEP) was synthesized from moso bamboo-derived lignin, and then lignin-based epoxy/titanium dioxide (LEP/TiO2) hybrid nanoparticle was synthesized via liquid deposition method for modifying lignin-based epoxy resin to prepare multifunctional bio-based epoxy. The results show that the LEP/TiO2 hybrid nanoparticle exhibits a stable topological surface shape and good dispersion and uniformity. By adding 10 wt% LEP/TiO2 hybrid nanoparticles, the multifunctional bio-based epoxy exhibits good mechanical strength and toughness, and the tensile strength and fracture toughness reach 36 MPa and 1.26 MPa·m1/2, respectively. In addition, the thermal stability, UV absorption and antibacterial properties of the multifunctional bio-based epoxy are further improved. This study provides a facile and efficient method for the preparation of high-performance multifunctional bio-based epoxy composite and a novel solution for the utilization of lignin.

Bioinspired Design of Strong, Tough, and Thermally Stable Polymeric Materials via Nanoconfinement.

The combination of high strength, great toughness, and high heat resistance for polymeric materials is a vital factor for their practical applications. Unfortunately, until now it has remained a major challenge to achieve this performance portfolio because the mechanisms of strength and toughness are mutually exclusive. In the natural world, spider silk features the combination of high strength, great toughness, and excellent thermal stability, which are governed by the nanoconfinement of hydrogen-bonded ß-sheets. Here, we report a facile bioinspired methodology for fabricating advanced polymer composite films with a high tensile strength of 152.8 MPa, a high stiffness of 4.35 GPa, and a tensile toughness of 30.3 MJ/m3 in addition to high thermal stability (69 °C higher than that of the polymer matrix) only by adding 2.0 wt % of artificial ß-sheets. The mechanical and thermostable performance portfolio is superior to that of its counterparts developed to date because of the nanoconfinement and hydrogen-bond cross-linking effects of artificial ß-sheets. Our study offers a facile biomimetic strategy for the design of integrated mechanically robust and thermostable polymer materials, which hold promise for many applications in electrical devices and tissue engineering fields.

Combination of lignin and L-lactide towards grafted copolymers from lignocellulosic butanol residue.

A series of BBL-graft-poly (L-lactide) copolymers were synthesized via ring-opening polymerization (ROP) of L-lactide (L-LA) with a biobutanol lignin (BBL) initiator and a triazabicyclodecene (TBD) catalyst under free-solvent at 135 °C. By manipulating the mass ratio of BBL/LLA, BBL-g-PLLA copolymers with tunable number-average molecular weight (Mn) (2544-7033 g mol(-1)) were obtained. The chemical structure of PLLA chains was identifiable by FT-IR, (1)H NMR and (13)C NMR spectroscopies, in combination with UV-vis spectra to provide support for the existence of the BBL in the copolymer. This provided solid evidence for the successful synthesis of BBL-g-PLLA copolymer. The thermal properties and surface characterization of BBL-g-PLLA copolymers were different from those of linear PLLA. Furthermore, the BBL-g-PLLA copolymer film showed good absorption capacity in the UV region and high transparency in the visible light region, which was expected to find significant applications in UV-protective coating film.

Preparation and characterization of Lignin-graft-poly (ɛ-caprolactone) copolymers based on lignocellulosic butanol residue.

In this paper, a "graft from" Ring-Opening Polymerization (ROP) technique was used to synthesize a lignin-graft-poly (ɛ-caprolactone) copolymer (BBL-g-PCL) using biobutanol lignin (BBL) as raw material recovered from lignocellulosic butanol residue. Polymerizations were carried out with various mass ratios of BBL and CL monomer ([BBL]/([BBL]+[CL])=1.0%, 5.0%, 10%, 20% and 40% (w/w)) to obtain BBL-g-PCL copolymers with different molecular weights, ranging from 367 to 8163gmol(-1). The grafting efficiency was preliminary evidenced by the long-term stability of dissolution of BBL-g-PCL in toluene. FT-IR and NMR analysis provided the further evidences for successful formation of BBL-g-PCL copolymer. The thermal properties of BBL-g-PCL copolymers were characterized by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). These results indicated that BBL-g-PCL copolymer had relatively good thermal stability. The static contact angle of BBL-g-PCL coating film reached to 80°. The surface functional groups and chemical composition of BBL-g-PCL copolymer was investigated in detail by X-ray photoelectron spectroscopy (XPS). The surface morphology of BBL-g-PCL copolymer was studied by Atomic force microscopy (AFM). Additionally, BBL-g-PCL coating film exhibited high absorption in the ultraviolet (UV) range, which could allow for applications in UV-blocking coatings, as well as the extents for the utilization of lignocellulosic butanol residue.