Macromolecular Materials and Engineering最新文献

Joining thermoplastic polymers (TPMs) and metals to form lightweight hybrid structures is of growing industrial and commercial importance. The performance of such materials relies on the bonding strength and endurance of the formed TPM–metal interfaces. The available joining technologies and the mechanisms that govern interfacial adhesion are reviewed in this contribution, highlighting thermal bonding as a commercially attractive joining method. By focusing on molecular interactions to optimize interfacial adhesion, the use of dopamine as a building block to form polydopamine (PDA) based adhesive interlayers in such interfaces is discussed. This work also highlights the potential of PDA to be applied as a load-bearing adhesive—a notion considered to date unfeasible.

Nanobody molecules, derived from heavy-chain only antibodies in camelids, represent the next generation of biotherapeutics. In addition to low immunogenicity, high stability, and potency, their single-domain format facilitates the construction of multivalent molecules for therapeutic applications. Although predominantly administered using a hypodermic syringe and needle, alternative delivery methods are under investigation. That said, the transdermal route has yet to be explored. Therefore, microarray patch (MAP) technology, offering a potentially high dose, pain-free transdermal system, is employed in this study. Trivalent Nanobody molecules, with and without half-life extension (VHH and VHH[HLE]), are formulated into hydrogel-forming MAPs, with pharmacokinetic parameters assessed in Sprague–Dawley rats. VHH MAPs exhibited a sustained release profile, with a serum concentration of 19 ± 9 ng mL⁻¹ 24 h post-administration. In contrast, a subcutaneous (SC) injection showed faster clearance, with a serum concentration of 1.1 ± 0.4 ng mL⁻¹ at 24 h. For VHH(HLE), both SC and MAP cohorts achieved a maximum serum concentration (T_max) at 24 h. The MAP cohort displayed a notable increase in VHH(HLE) serum levels between 6–24 h, dropping after MAP removal. This study has exemplified MAPs potential for delivering advanced biologics, indicating the transdermal route's promise for pain-free, patient-friendly administration of Nanobody molecules.

Amphiphilic cyclic dipeptides are efficient supramolecular hydrogelators. They can be combined with molecular photoswitches to produce light-responsive soft materials, which can be applied in controlled drug delivery. Here it is reported that an arginine-containing cyclic dipeptide decorated with ortho-fluorinated azobenzene forms hydrogels under physiological conditions that can be reversibly liquefied upon exposure to visible light frequencies (green and violet, respectively). The addition of sodium alginate results in composite supramolecular hydrogels with increased gelating capacity supported with Coulombic interactions, which also reversibly dissipate upon irradiation.

Front Cover: The cover page of article 2300337 by Filipe Natalio and co-workers shows the chemosynthesis of a glucose derivative depicted in the upper part of the illustration. This last compound is fed to a floating cotton ovule in vitro culture (central illustration), becoming integrated into the fibers (blue dots). These modified fibers show increased mechanical properties, as depicted with the clamps in the lower part of the illustration.

In this study, Acrylonitrile butadiene styrene (ABS) with three different ratios of 30%, 50%, and 70% is used to enhance the shape memory and mechanical properties of Polyethylene terephthalate glycol (PETG). Additionally, morphology, printability, and dynamic thermomechanical analysis are also examined. The thermal test results show that PETG-ABS compounds have two transition temperatures in the range of 80 and 110 °C, which are related to the components. By changing the weight percentage of PETG from 30 to 70%, three morphologies of matrix-droplet, sea-island, and combination of co-continuous and matrix-droplet are observed. The results of the mechanical properties show an increase in strength with the increase of ABS, which can be justified due to the higher strength of ABS compared to PETG. The highest tensile strength of 32.48 MPa and 15.16% elongation is obtained for PETG-ABS(30-70) and PETG-ABS(70-30), respectively. Due to the better shape memory performance of PETG, PETG-ABS(50-50) and PETG-ABS(70-30) have complete shape recovery, and with the increase of PETG, the shape recovery rate also increased. This diversity in morphology, mechanical properties, and shape memory effect is one of the goals of this research which is well fulfilled.

The recycling of polyolefins for multiple life cycles is becoming a legislative requirement in the South African plastics industry. This study shows that this cannot be a blanket requirement for all polyolefins. While HDPE displays good resistance to weathering, the decrease in molecular weight limits the maximum number of life cycles before which the resultant product has lost all integrity. Impact polypropylenes fare much worse during weathering and more than 50% of impact properties are lost within the first 12 months of exposure. The blending of virgin material into degraded material can recover some properties of HDPE but not in the case of impact polypropylenes. The same legislation can therefore not be applied to all plastics and specific targets should depend on polymer composition.

Polycaprolactone (PCL) is one of the durable polymers with potential in a plethora of healthcare applications. Its biological properties, degradability, chemical properties, and mechanical properties can further be modified to manufacture desired products for modern biomedical applications. Electrospinning of PCL offers the opportunity to design treatment materials that resemble human tissues and facilitate regeneration at the target site. The resultant materials can also be modified by loading other active functional materials to broaden their applications. Herein, the recent advances in the preparation and modification of PCL-based materials for healthcare applications are elucidated. The challenges and future trends for its application in modern biomedical applications are also outlined.

Collagen nanofibers can be employed in hydrogels to create injectable nanocomposite hydrogels, mimicking the fibrous architecture of the natural extracellular matrix (ECM). As long continuous electrospun collagen nanofibers are not applicable, fragmentation is inevitable to obtain injectable hydrogels with a fine viscosity. Here, four methods: hand grinding (HG), homogenizer (HM), mixer milling (MM), and ultrasonication (UH) are used to disintegrate and shorten collagen nanofiber mats before incorporation into an injectable hyaluronic acid hydrogel as a matrix. The Length-to-diameter (L/d) ratio and morphology of fragmented collagen are compared by SEM. The injection force, mechanical properties, and cell viability of the selected collagen-incorporated hydrogels are also evaluated. UH emerges as the most effective method, yielding the highest L/d ratio of 46 and a notable compressive modulus of 8.7 ± 0.92 kPa. Assessment of the in vitro cell viability of the encapsulated chondrocytes in the collagen-incorporated hydrogels demonstrates good biocompatibility, and hydrogels containing UH short nanofiber, in particular, show an increase in cell proliferation. This work indicates how collagen mats can be effectively broken down and combined with injectable hydrogels to enhance both their mechanical behavior and biocompatibility.

In the present study, polystyrene (PS) is chemically modified with diethyl(acryloyloxymethyl)phosphonate (DEAMP) and an N-containing monomer, selected from different classes of compounds, via a ter-polymerization route; thus, exploring possible P–N synergistic effects on fire retardance of the base polymer. The successful incorporation of P and N monomeric units is confirmed by Fourier Transform Infrared (FT-IR), ¹H and ³¹P Nuclear Magnetic Resonance (NMR) spectroscopies. The thermal degradation and combustion attributes of modified polymeric materials are measured using standard techniques, including Thermo-Gravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC), “bomb” calorimetry, and Pyrolysis Combustion Flow Calorimetry (PCFC). The thermal and combustion studies demonstrate that the thermal stability and combustion characteristics of styrenic polymers are significantly altered by the presence of even nominal amounts of P- and N-containing groups, and in certain cases, synergistic interactions of these groups are also evident. For instance, as revealed by TGA, the extent of char formation, under the oxidative atmosphere, in the prepared ter-polymers, is enhanced by 16–44%, when compared to the unmodified PS. The heat release rates and heat release capacities of ter-polymers, measured using the PCFC technique, are reduced by 18–50%, in comparison to the same parameters obtained for the unmodified counterpart.