Effect of the acrylic acid content on the permeability and water uptake of poly(styrene-co-butyl acrylate) latex films

Engineered living photosynthetic biocomposites for intensified biological carbon capture

Carbon capture and storage is required to meet Paris Agreement targets. Photosynthesis is nature's carbon capture technology. Drawing inspiration from lichen, we engineered 3D photosynthetic cyanobacterial biocomposites (i.e., lichen mimics) using acrylic latex polymers applied to loofah sponge. Biocomposites had CO₂ uptake rates of 1.57 ± 0.08 g CO₂ g^-1_biomass d^-1. Uptake rates were based on the dry biomass at the start of the trial and incorporate the CO₂ used to grow new biomass as well as that contained in storage compounds such as carbohydrates. These uptake rates represent 14-20-fold improvements over suspension controls, potentially scaling to capture 570 tCO₂ t^-1_biomass yr^-1, with an equivalent land consumption of 5.5-8.17 × 10⁶ ha, delivering annualized CO₂ removal of 8-12 GtCO₂, compared with 0.4-1.2 × 10⁹ ha for forestry-based bioenergy with carbon capture and storage. The biocomposites remained functional for 12 weeks without additional nutrient or water supplementation, whereupon experiments were terminated. Engineered and optimized cyanobacteria biocomposites have potential for sustainable scalable deployment as part of humanity's multifaceted technological stand against climate change, offering enhanced CO₂ removal with low water, nutrient, and land use penalties.

Understanding and Improving the Oil and Water Barrier Performance of a Waterborne Coating on Paperboard

Using paperboard as packaging material is more sustainable than using plastic. To be a viable replacement, however, the barrier properties of paperboard need to be improved. Applying a waterborne barrier coating for both oil and water is an attractive method to improve the barrier performance of paperboard food packaging. However, not much is known about the oil and water barrier properties and penetration pathways of such coatings. Here, an alkali-soluble resin (ASR)-stabilized waterborne emulsion polymer was prepared and applied on untreated paperboard. Its performance as oil and water barrier coating was investigated, and the penetration pathways for both oil and water through the coating are discussed. The presence of surface defects in the coating applied on the paperboard strongly affects both the oil and water barrier properties, but the coating's morphology and chemical nature only play a major role in the water barrier performance. The optimal barrier performance for oil and water was achieved when adding 5 wt % isopropanol (IPA) to the dispersion and applying two coating layers on paperboard. The IPA improves film formation and reduces the number of surface defects, which is explained by a more favorable spreading coefficient of the coating over the paperboard substrate. These insights will help to improve the oil and water barrier properties of polymer-coated paperboard for more sustainable packaging applications.

The Properties of Solvent-Based and Water-Borne Butyl Acrylate/Styrene Copolymer Films

With the increasing demands of environmental protection, the properties of water-borne coatings film must meet or exceed current solvent-based coatings. It is an important part of coating science for characterizing the film properties of polymers which was used in the water-borne and the solvent-based coating. In this study, UV-visible spectroscopy, gravimetric analysis, scanning electron microscopy, and electrochemical impedance spectroscopy were used to characterize the properties of the water-borne and the solvent-based poly(butyl acrylate/styrene) (P(BA/St)) copolymer films. The water-borne and the solvent-based P(BA/St) copolymer was synthesized by two methods. The copolymer had a Tg of approximately 14.4°C, which was close to room temperature. The water-borne copolymers were prepared via a three-step film formation process, while the solvent-based copolymer films were prepared in two steps. Comparing the properties of the water-borne and the solvent-based films, the water absorption capacities decreased with increasing film formation times, and the film barrier properties and electrochemical properties of both films improved as the film formation time increased.

Role of the Hydrophilic Latex Particle Surface in Water Diffusion into Films from Waterborne Polymer Colloids

The diffusion mechanism and growth of large-scale domains during the immersion of latex films in water have been thoroughly investigated with scattering techniques in a combination with the gravimetric method. Latex dispersions for film formation studies had identical main monomer compositions and only differ in the hydrophilic comonomers that result in distinct "hairy" layer structures of the particles. The major effects of the presence and the structure of the surface layers were identified: (1) Introducing the hydrophilic surface layer in the binder structure results in a more uniform penetration of water and a reduction in the water domain growth. (2) The nature of the particle shell defines the rate of the formation of the first hydration layer and the beginning of the large cluster formation. Poly(acrylamide) in the particle shell promotes the formation of the homogeneously swollen film and slows down the development of water "pockets." Poly(acrylic acid) leads to a more heterogeneous material and accelerates water uptake and cluster growth. (3) The thickness of the particle hairy layer regulates the thickness of the interstitials in the dry film and the number of the chemical groups involved in H-bonding with water molecules without a cluster formation. The amount of water that was absorbed before large domains start evolving increased with the growth of the particle shell thickness.

pH dependence of the properties of waterborne pressure-sensitive adhesives containing acrylic acid

Polymer colloids are often copolymerized with acrylic acid monomers in order to impart colloidal stability. Here, the effects of the pH on the nanoscale and macroscopic adhesive properties of waterborne poly(butyl acrylate-co-acrylic acid) films are reported. In films cast from acidic colloidal dispersions, hydrogen bonding between carboxylic acid groups dominates the particle-particle interactions, whereas ionic dipolar interactions are dominant in films cast from basic dispersions. Force spectroscopy using an atomic force microscope and macroscale mechanical measurements show that latex films with hydrogen-bonding interactions have lower elastic moduli and are more deformable. They yield higher adhesion energies. On the other hand, in basic latex, ionic dipolar interactions increase the moduli of the dried films. These materials are stiffer and less deformable and, consequently, exhibit lower adhesion energies. The rate of water loss from acidic latex is slower, perhaps because of hydrogen bonding with the water. Therefore, although acid latex offers greater adhesion, there is a limitation in the film formation.