Polymer Factory (Sweden)

ABSTRACT Starch microspheres are employed in medicinal products as embolization agents and drug delivery vehicles. For the encapsulation of sensitive ingredients, mild cross‐linking techniques are needed, prompting interest in physical cross‐linking via starch crystallization. This study investigates starch microsphere formation and crystallization kinetics in aqueous two‐phase systems (ATPS) with various continuous phase polymers, using confocal Raman microscopy, X‐ray scattering, isothermal calorimetry, and light microscopy. The results showed that the solidification of starch particles depends on the ATPS polymers, being fastest in polyethylene glycol (PEG), followed by poly(2‐ethyl‐2‐oxazoline) (PEtOx), and polyvinyl pyrrolidone (PVP). Confocal Raman microscopy can be used to follow the crystallization process, and its results match those from X‐ray crystallography. Raman microscopy demonstrated uniform structural changes from amorphous to crystalline starch, with PEG and PEtOx facilitating faster crystallization than PVP. X‐ray diffraction and isothermal calorimetry also demonstrated faster crystal growth and heat flow development in PEG and PEtOx formulations compared to PVP. Analysis of the kinetics using the Avrami model indicated that crystallization is uniform across the microspheres. Combining these results with light microscopy observations revealed that starch solidification occurs in the early stages of the crystallization process. In conclusion, the continuous phase polymer impacts the crystallization kinetics and structural evolution of starch microspheres, with PVP leading to slower crystallization compared to PEG and PEtOx. This suggests that polymer selection is crucial for tailoring the crystallization process of starch‐based microspheres.

Due to new environmental trends and restrictions and due to more interest in using renewable materials with circularity, wood has become an important group of building materials. In Scandinavia, wood is a preferred building material where wooden laminates and parquet flooring are extremely popular in housing. Since wood contain terpene compounds and the flooring materials use a lot of adhesives to obtain different structures depending on if it is a parquet or a laminate flooring, it is of interest to investigate how such materials influence the indoor air quality (IAQ) and if the emitted compounds may contribute to health problems. In this study, primary emissions from several commercially available wooden flooring materials such as parquet and laminated flooring are presented. Since indoor air climate is very much dependent on the emission of volatile organic compounds from the building materials, we investigated such materials from the point of view of emission of volatile organic compounds and aldehydes. Since aldehydes are more toxic, it is of interest to review some of such data for aldehydes in this paper, which are necessary to obtain good indoor air quality. Health risks may mainly arise from the emission of terpene compounds and aldehydes from such flooring materials. According to international Occupational Exposure Limit levels (OEL), aldehydes are very hazardous for health at relatively low concentrations. They are also classified as human carcinogens according to EPA. Aldehydes are mainly formed from the oxidation of terpenes and from urea formaldehyde (UF) adhesives that are mainly present as adhesives in the flooring materials. In this paper I shall also review the standards that are used to approve such flooring products and the mechanisms behind the emission of aldehydes from UF adhesives. Our studies show that the levels of primary emissions are relatively high in such flooring materials and varies depending on if it is a parquet or laminate. These emissions may influence the indoor air quality and thereby may cause serious health problems. We have found that even an eco-labeled flooring material showed relatively high emission levels. This study reveals further that the standard used for the certification of building materials is not relevant to IAQ because they do not measure the total amount of free volatiles present in the flooring materials. The study reveals that to assure IAQ it is extremely important that the building materials are analyzed and specially when it concerns wooden materials.

Abstract Natural polymers such as collagen are popular materials for tissue engineering scaffolds due to their innate bioactivity and biocompatibility. Being derived from animal sources, however, means that batch‐to‐batch consistency is often low and the extraction of collagen is costly. This conundrum facilitates the need for synthetic alternatives as scaffolding materials. In this study, a system of poly(ethylene glycol) (PEG)‐based thiol‐ene coupled (TEC) hydrogel scaffolds is presented for tissue engineering purposes. The platform includes several necessary features, namely cytocompatibility, high swelling ability, biodegradability, tunable stiffness, and fast, straightforward fabrication. The swelling ability is provided by the hydrophilicity of the ether‐links of PEG, which facilitated the formation of high water content hydrogels that match the water content of soft tissues for the proper diffusion of nutrients and waste compounds. TEC ensures fast and facile fabrication, with cross‐linking moieties that allow for the biodegradation of the hydrogel network through hydrolytic cleavage. The mechanical properties of the scaffolds are made tunable in the range of storage moduli spanning <1 kPa to >100 kPa. It is also shown that despite the synthetic nature of the hydrogels, human dermal fibroblasts and murine macrophages, Raw 264.7, were able to survive and produce extracellular protein excretions while embedded in the 3D hydrogels.

Microplastics have recently become a major environmental issue due to their ubiquitous distribution, uncontrolled environmental occurrences, small sizes and long lifetimes. Actual remediation methods include filtration, incineration and advanced oxidation processes such as ozonation, but those methods require high energy or generate unwanted by-products. Here we tested the degradation of fragmented, low-density polyethylene (LDPE) microplastic residues, by visible light-induced heterogeneous photocatalysis activated by zinc oxide nanorods. The reaction was monitored using Fourier-transform infrared spectroscopy, dynamic mechanical analyser and optical imaging. Results show a 30% increase of the carbonyl index of residues, and an increase of brittleness accompanied by a large number of wrinkles, cracks and cavities on the surface. The degree of oxidation was directly proportional to the catalyst surface area. A mechanism for polyethylene degradation is proposed.

We present experiments and simulations on the electrical conduction currents of purified transformer oil with and without surface-modified MgO nanoparticles. Results show that on the injection regi ...

The utilization of dendrimer calibrants as an alternative to peptides and proteins for high mass calibration is explored. These synthetic macromolecules exhibited a number of attractive advantages, including exceptional shelf-lives, broad compatibility with a wide range of matrices and solvents, and evenly spaced calibration masses across the mass range examined, 700-30,000 u. The exceptional purity of these dendrimers and the technical simplicity of this calibration platform validate their broad relevance for high molecular weight mass spectrometry.