Tracking phase transitions of tactoids in sulfated cellulose nanocrystals using second harmonic generation microscopy.

Cellulose nanocrystals (CNCs) have emerged as promising candidates for chiroptical functional materials due to their ability to form cholesteric liquid crystals with tunable periodicity. The quality of the final cholesteric phase is influenced by the nucleation, growth and coalescence mechanism of the initial droplets, known as tactoids. Current research focuses on understanding the size and morphological transformations of these tactoids, to gain deeper insights into their dynamic behavior and, in turn, to better control the final properties of novel photonic materials.

Photocatalytic Transformation of Isotactic Polypropylene Using Phthalimide N-Oxyl Radicals Under Mild Conditions.

Incorporating polar functionality into C(sp3)─H bonds in isotactic polypropylene (iPP) without compromising its molecular weight during post-polymerization modification has long been a challenge due to competing chain degradation reactions. Here, a facile, radically mediated approach is presented that enables chain functionalization without chain scission. To achieve this, a photocatalytic process is designed that operates under mild conditions, maintaining iPP in a gel state.

In-situ observation of gel-to-gel transition in dipeptide hydrogel using SHG microscopy.

Peptide-based hydrogels formed by FmocFF (9-fluorenylmethoxycarbonyl-diphenylalanine) are established materials in tissue engineering, drug delivery, and bioelectronics. Although initial assembly processes and final states are relatively well known, the possibility of hidden, intermediate gel forms remains underexplored. Such "gel-to-gel" transitions may yield previously unnoticed polymorphs with distinct mechanical and structural features, expanding options for tuning gel functionality.

Investigating the Nanoscale Dynamics of Flocculation with Pyridinium-Modified Cellulose Nanocrystals.

Microalgae show significant potential as a sustainable resource for the production of food, animal feed, biofuels, and several high-value products. However, the lack of effective harvesting techniques limits the large-scale production of microalgae. A strategy to enhance the separation of microalgae from their growth media is to flocculate the microalgae cells into larger particles that can then be separated from water by sedimentation or flotation.

Quantitative DSC Assessment of the Polymorph-Specific Crystallinity of Poly(Lactic Acid) and the Impact of a Self-Assembling Nucleating Agent and PEG Plasticizer.

This study examines the temperature-resolved, polymorph-specific crystallinity of poly(lactic acid), PLA, during cooling and heating at 10 °C/min, with a focus on the effects of N, N-bis(benzoyl) hexanedioic acid dihydrazide (BHAD, commercially known as TMC306) as nucleating agent and PEG 1000 as plasticizer. A semicrystalline (PLA-1) and amorphous (PLA-2) PLA grade were investigated. The study emphasizes the importance of using temperature-dependent, polymorph-specific transition enthalpies to accurately calculate crystallinities from Differential Scanning Calorimetry (DSC).

Laccase-Mediated Incorporation of Xylans and Lignin-Carbohydrate Complexes into High-Yield Eucalyptus Kraft Fibers.

Water-soluble products derived from biomass processing hold significant potential to enhance biorefinery viability due to their versatile applications. However, their use in the modification of paper products remains underexplored. Here, corn stover and sugarcane bagasse provided water-soluble products being incorporated into high-yield eucalyptus kraft pulps.

Amorphous-to-Crystalline Transformation: How Cluster Aggregation Drives the Multistep Nucleation of ZIF-8.

Nucleation, the pivotal first step of crystallization, governs the essential characteristics of crystallization products, including size distribution, morphology, and polymorphism. While understanding this process is paramount to the design of chemical, pharmaceutical, and industrial production processes, major knowledge gaps remain, especially with respect to the crystallization of porous solids. Also for nanocrystalline ZIF-8, one of the most widely studied metal-organic frameworks, questions regarding the species involved in the nucleation pathway and their structural and chemical transformations remain unanswered.

Tuning the Crystallinity of a Metal-Organic Coordination Network at the Liquid-Solid Interface.

Single layered metal-organic coordination networks (MOCNs) are gaining attention thanks to their unique electronic and magnetic properties. The presence of coordinatively unsaturated metal sites within their structures provides additional binding locations for substrates in catalytic processes. Consequently, MOCNs fabricated on solid surfaces are emerging as promising candidates for use in solution-based heterogeneous applications.

Effects of microplastics on Daphnia-associated microbiomes in situ and in vitro.

Microplastic pollution in aquatic environments is a growing global concern. Microplastics, defined as plastic fragments smaller than 5 mm, accumulate in freshwater reservoirs, especially in urban areas, impacting resident biota. This study examined the effects of microplastics (MP) on the performance and microbiome of Daphnia, a keystone organism in freshwater ecosystems, through both in situ sampling of freshwater ponds and a controlled 23-day in vitro exposure experiment.

Imaging with a twist: Three-dimensional insights of the chiral nematic phase of cellulose nanocrystals via SHG microscopy.

Cellulose nanocrystals (CNCs) are bio-based nanoparticles that, under the right conditions, self-align into chiral nematic liquid crystals with a helical pitch. In this work, we exploit the inherent confocal effect of second-harmonic generation (SHG) microscopy to acquire highly resolved three-dimensional (3D) images of the chiral nematic phase of CNCs in a label-free manner. An in-depth analysis revealed a direct link between the observed variations in SHG intensity and the pitch.

Optically Active, Paper-Based Scaffolds for 3D Cardiac Pacing.

In this work, we report the design and fabrication of a light-addressable, paper-based nanocomposite scaffold for optical pacing and read-out of in vitro grown cardiac tissue. The scaffold consists of paper cellulose microfibers functionalized with gold nanorods (GNRs) and semiconductor quantum dots (QDs), embedded in a cell-permissive collagen matrix. The GNRs enable cardiomyocyte activity modulation through local temperature gradients induced by modulated near-infrared (NIR) laser illumination, with the local temperature changes reported by temperature-dependent QD photoluminescence (PL).

The comparative toxicity of biobased, modified biobased, biodegradable, and petrochemical-based microplastics on the brackish water flea Diaphanosoma celebensis.

The escalating production and improper disposal of petrochemical-based plastics have led to a global pollution issue with microplastics (MPs), which pose a significant ecological threat. Biobased and biodegradable plastics are believed to mitigate plastic pollution. However, their environmental fate and toxicity remain poorly understood.

Peptide Sequence Variations Govern Hydrogel Stiffness: Insights from a Multi-Scale Structural Analysis of H-FQFQFK-NH Peptide Derivatives.

Throughout the past decades, amphipathic peptide-based hydrogels have proven to be promising materials for biomedical applications. Amphipathic peptides are known to adopt β-sheet configurations that self-assemble into fibers that then interact to form a hydrogel network. A fundamental understanding of how the peptide sequence alters the structural properties of the hydrogels would allow for a more rational design of novel peptides for a variety of biomedical applications in the future.

Thermodynamics of interactions between cellulose nanocrystals and monovalent counterions.

Alkali and quaternary ammonium cations interact with negatively charged cellulose nanocrystals (CNCs) bearing sulfated or carboxylated functional groups. As these are some of the most commonly occurring cations CNC encounter in applications, the thermodynamic parameters of these CNC-counterion interactions were evaluated with isothermal titration calorimetry (ITC). Whereas the adsorption of monovalent counterions onto CNCs was thermodynamically favourable at all evaluated conditions as indicated by a negative Gibbs free energy, the enthalpic and entropic contributions to the CNC-ion interactions were found to be strongly dependent on the hydration characteristics of the counterion and could be correlated with the potential barrier to water exchange of the respective ions.

Dimensions of Cellulose Nanocrystals from Cotton and Bacterial Cellulose: Comparison of Microscopy and Scattering Techniques.

Different microscopy and scattering methods used in the literature to determine the dimensions of cellulose nanocrystals derived from cotton and bacterial cellulose were compared to investigate potential bias and discrepancies. Atomic force microscopy (AFM), small-angle X-ray scattering (SAXS), depolarized dynamic light scattering (DDLS), and static light scattering (SLS) were compared. The lengths, widths, and heights of the particles and their respective distributions were determined by AFM.

Covalent immobilization of N-heterocyclic carbenes on pristine carbon substrates: from nanoscale characterization to bulk catalysis.

To control the synthesis of designer catalysts on graphitic materials up to the nanometer scale, methods should be provided that combine both nanoscale characterization and bulk scale experiments. This work reports the grafting of N-heterocyclic carbene (NHC)-type catalysts on graphite, both at nanometer and bulk scale, as it allows increased insights into the nature of the immobilized catalysts.

Heterogeneous Pt-catalyzed transfer dehydrogenation of long-chain alkanes with ethylene.

The dehydrogenation of long-chain alkanes to olefins and alkylaromatics is a challenging endothermic reaction, typically requiring harsh conditions which can lead to low selectivity and coking. More favorable thermodynamics can be achieved by using a hydrogen acceptor, such as ethylene. In this work, the potential of heterogeneous platinum catalysts for the transfer dehydrogenation of long-chain alkanes is investigated, using ethylene as a convenient hydrogen acceptor.

Gamma radiation effects on AG MP-50 cation exchange resin and sulfonated activated carbon for bismuth-213 separation.

Medical Ac/Bi radionuclide generators are designed to provide a local supply of the short-lived Bi for cancer treatment. However, radiation-induced damage to the sorbents commonly used in such radionuclide generators remains a major concern. In this study, the effects of gamma radiation on AG MP-50 cation exchange resin and sulfonated activated carbon (SAC) were studied by analyzing the changes in the morphological characteristics, functional groups, and the La/Bi sorption performance, with La being a suitable non-radioactive substitute for Ac.

On the nucleation and fast reaction kinetics of 2D polymerisation with a 2-in-1 monomer.

We report on the fast reaction kinetics of an imine based 2D polymer (2DP) formed from a single monomer carrying both aldehyde and amine groups. Our results point towards a direct monomer-to-crystalline polymer transition without an amorphous intermediate.

Review on the Degradation of Poly(lactic acid) during Melt Processing.

This review paper presents an overview of the state of the art on process-induced degradation of poly(lactic acid) (PLA) and the relative importance of different processing variables. The sensitivity of PLA to degradation, especially during melt processing, is considered a significant challenge as it may result in deterioration of its properties. The focus of this review is on degradation during melt processing techniques such as injection molding and extrusion, and therefore it does not deal with biodegradation.

Phase behavior of medium-length hydrophobically associating PEO-PPO multiblock copolymers in aqueous media.

Hypothesis: The micellization of block copolymers of poly(ethylene oxide) (PEO) and poly(propylene oxide) (PPO) is driven by the dehydration of PPO at elevated temperatures. At low concentrations, a viscous solution of isolated micelles is obtained, whereas at higher concentrations, crowding of micelles results in an elastic gel. Alternating PEO-PPO multiblock copolymers are expected to exhibit different phase behavior, with altered phase boundaries and thermodynamics, as compared to PEO-PPO-PEO triblock copolymers (Pluronics®) with equal hydrophobicity, thereby proving the pivotal role of copolymer architecture and molecular weight.