Tailored cellulose nanocrystals as a functional ultraviolet absorbing nanofiller of epoxy polymers

Nano-enabled smart and functional materials toward human well-being and sustainable developments

Fabrication and operation on increasingly smaller dimensions have been highly integrated with the development of smart and functional materials, which are key to many technological innovations to meet economic and societal needs. Along with researchers worldwide, the Waterloo Institute for Nanotechnology (WIN) has long realized the synergetic interplays between nanotechnology and functional materials and designated 'Smart & Functional Materials' as one of its four major research themes. Thus far, WIN researchers have utilized the properties of smart polymers, nanoparticles, and nanocomposites to develop active materials, membranes, films, adhesives, coatings, and devices with novel and improved properties and capabilities. In this review article, we aim to highlight some of the recent developments on the subject, including our own research and key research literature, in the context of the UN Sustainability development goals.

Nanocelluloses as skin biocompatible materials for skincare, cosmetics, and healthcare: Formulations, regulations, and emerging applications

Nowadays, skin biocompatible products are fast-growing markets for nanocelluloses with increasing number of patents published in last decade. This review highlights recent developments, market trends, safety assessments, and regulations for different nanocellulose types (i.e. nanoparticles, nanocrystals, nanofibers, nanoyarns, bacterial nanocellulose) used in skincare, cosmetics, and healthcare. The specific properties of nanocelluloses for skincare include high viscosity and shear thinning properties, surface functionality, dispersion stability, water-holding capacity, purity, and biocompatibility. Depending on their morphology (e.g. size, aspect ratio, geometry, porosity), nanocelluloses can be used as formulation modifiers, moisturizers, nanofillers, additives, membranes, and films. Nanocellulose composite particles were recently developed as carriers for bioactive compounds or UV-blockers and platforms for wound healing and skin sensors. As toxicological assessment depends on morphologies and intrinsic properties, stringent regulation is needed from the testing of efficient nanocellulose dosages. The challenges and perspectives for an industrial breakthrough are related to optimization of production and processing conditions.

Recent Advances on Cellulose Nanocrystals and Their Derivatives

Nanocellulose, typically cellulose nanocrystals (CNCs), has excellent properties and is widely used. In particular, CNC has a small dimension, high chemical reactivity, and high sustainability, which makes it an excellent candidate as a starting material to be converted into nanocellulose derivatives. Chemical modification is essential for obtaining the desired products; the modifications create different functional attachment levels and generate novel microstructures. Recent advances on nanocellulose derivatives have not yet been reviewed and evaluated for the last five years. Nanocellulose derivative materials are being used in a wide variety of high-quality functional applications. To meet these requirements, it is essential for researchers to fully understand CNCs and derivative materials, precisely their characteristics, synthesis methods, and chemical modification approaches. This paper discusses CNC and its derivatives concerning the structural characteristics, performance, and synthesis methods, comparing the pros and cons of these chemical modification approaches reported in recent years. This review also discusses the critical physicochemical properties of CNC derivative products, including solubility, wetting performance, and associated impacts on properties. Lastly, this paper also comments on the bottlenecks of nanocellulose derivatives in various applications and briefly discusses their future research direction.

Date pits based nanomaterials for thermal insulation applications-Towards energy efficient buildings in Qatar

Air-conditioning systems make the most significant part of energy consumption in the residential sector. There is no denying that it is essential to produce a comfortable indoor thermal environment for residents in a building. The actual goal is to achieve thermal comfort level without putting too much cost on the ecological system by trying to conserve the amount of energy consumed. An effective way to help achieve such a goal is by incorporating thermal insulation in buildings. Thermal insulations help reduce thermal energy gained during the implementation of a desired thermal comfort level. This study aims to use an environmentally friendly nanoparticle of date pits to create thermal insulations that can be used in buildings. Different ratios of the nanoparticle of the date pits and sand composite were investigated. Fourier transform infrared spectroscopy and scanning electron microscopy were used to characterize the new materials. The material with nanoparticles of date pits and 50% by-volume epoxy provided good thermal insulation with thermal conductivity of 0.26 W⁄mK that could be used in the existing buildings. This has the potential to reduce the overall energy consumption by 4,494 kWh and thereby reduce CO2 emissions of a 570 m2 house by 1.8 tons annually. In conclusion, the future of using nanoparticles of date pits in construction is bright and promising due to their promising results.

Recent studies on modified cellulose/nanocellulose epoxy composites: A systematic review

Cellulose and its derivatives are widely explored for films and thickening of pharmaceutical solutions, in paints, as reinforcement in composites, among others. This versatility is due to advantages such as renewability, low cost, and environmental friendliness. When used in polymer composites, due to the hydrophilic character of the cellulose, surface chemical modification is highly recommended to improve its compatibility with the polymeric matrix. Hence, this paper presents a systematic review of chemically modified cellulose/epoxy resin composites focusing on the last five years. The investigation followed the PRISMA protocol that delivers a meticulous summary of all available primary research in response to a research question. After including/excluding steps, thirty-six studies were included in the review. The results were presented focusing on thermal, mechanical and dynamic-mechanical properties of the composites. In brief, this methodology helped identifying the main gaps in knowledge in that field.

Multilayer assemblies of cellulose nanocrystal - polyvinyl alcohol films featuring excellent physical integrity and multi-functional properties

A simplistic approach to cellulose nanocrystals (CNCs) percolation at low concentrations with multifold increases in properties, through the development of multilayered film assemblies was employed. CNC networks combined with polyvinyl alcohol (PVOH) thin films were fabricated leading to multilayer assembly of randomly aligned CNC nanorod bundles, similar to those found in biological structures. Oxygen impermeable barrier property of the films was achieved. The optical clarity remained mostly pristine while exhibiting improved UV absorbance. These films can be applied towards shielding UV sensitive materials that require optical transparency. A 415 and 2300% increase in strength and modulus, respectively, were observed for multilayered film with 10 wt% CNC loading as compared to the baseline neat PVOH film. The multilayers and networks formed through strong hydrogen bonds and structural alignment of the CNCs make this strategy effective in achieving enhanced properties at low CNCs loadings, which can be applied to other polymer films with property limitations.

A Biorefinery Strategy That Introduces Hydrothermal Treatment Prior to Acid Hydrolysis for Co-generation of Furfural and Cellulose Nanocrystals

Hydrothermal treatment of wood pulp at 150-225°C prior to acid hydrolysis was investigated in the context of isolating cellulose nanocrystals (CNCs). The objective was 2-folds as follows: (a) generating furfural as a value-added co-product; and (b) concentrating and forming new CNC precursors through thermal re-orientation of para-crystalline cellulose chains that will in turn improve CNC recovery and yield. Furfural yields up to 19 and 21% xylan conversion were obtained at 200 and 225°C hydrothermal treatments, respectively. In addition, these hydrothermal treatment conditions increased the crystallinity index of the pulp (77%) to 84 and 80%, respectively. Consequently, the CNC yield from hydrothermally treated wood pulp, when compared to untreated wood pulp, improved by up to 4- and 2-folds, respectively. An efficient acid hydrolysis process with yield improvements can translate to reduced CNC isolation and purification costs and increased production capacity. The qualities of the CNCs in terms of particle size and crystallinity were not affected due to hydrothermal treatment. However, the zeta potential, sulfur, hydrogen, and oxygen content of the CNCs were significantly lower at 225°C while carbon composition increased, and dark brown coloration was observed that indicates caramelization. This study demonstrates for the first time a novel biorefinery strategy that introduces hydrothermal treatment prior to acid hydrolysis to co-generate furfural and CNC with improved efficiency.