Multicomponent Stress‐Sensing Composites Fabricated by 3D‐Printing Methodologies

3D Printing of Triamcinolone Acetonide in Triblock Copolymers of Styrene–Isobutylene–Styrene as a Slow-Release System

Additive manufacturing has a wide range of applications and has opened up new methods of drug formulation, in turn achieving attention in medicine. We prepared styrene–isobutylene–styrene triblock copolymers (SIBS; Mn = 10 kDa–25 kDa, PDI 1,3–1,6) as a drug carrier for triamcinolone acetonide (TA), further processed by fused deposition modeling to create a solid drug release system displaying improved bioavailability and applicability. Living carbocationic polymerization was used to exert control over block length and polymeric architecture. Thermorheological properties of the SIBS polymer (22.3 kDa, 38 wt % S) were adjusted to the printability of SIBS/TA mixtures (1–5% of TA), generating an effective release system effective for more than 60 days. Continuous drug release and morphological investigations were conducted to probe the influence of the 3D printing process on the drug release, enabling 3D printing as a formulation method for a slow-release system of Triamcinolone.

3D-printing of the polymer/insect-repellent system poly(l-lactic acid)/ethyl butylacetylaminopropionate (PLLA/IR3535)

The polymer/solvent system poly(l-lactic acid)/ethyl butylacetylaminopropionate (PLLA/IR3535) is regarded as an insect-repellent-delivery system, serving, e.g., for fighting mosquito-borne tropical diseases. In such systems the solid polymer hosts the liquid repellent, with the latter slowly released to the environment, expelling mosquitoes. As a new approach, exceeding prior work about application of different technologies to obtain such devices, in this work, samples of the polymer/repellent system PLLA/IR3535 were prepared by 3D-printing. The experiments showed that it is possible to print 3D-parts containing up to 25 m% repellent, with an only minor loss of repellent during the printing process. For samples containing low amount of repellent, crystallization of PLLA was suppressed due to the rather fast cooling step and the low bed temperature of around 25 °C, being lower than the glass transition temperature of the homogeneous polymer/repellent strands. At higher repellent concentration, due to the lowering of the glass transition temperature to near or even below ambient temperature, the crystallinity slowly increased during storage after printing. For all samples, regardless of the initial repellent concentration, the repellent-release rate increases with temperature, and at ambient temperature the release-time constant is in the order of 10 days. The study successfully proved the applicability of the technology of extrusion-based 3D-printing for the preparation of polymer parts with a specific shape/design containing mosquito-repellent at a concentration which raises the expectation to be used as a repellent delivery-device.

3D Printable Composite Polymer Electrolytes: Influence of SiO2 Nanoparticles on 3D-Printability

We here demonstrate the preparation of composite polymer electrolytes (CPEs) for Li-ion batteries, applicable for 3D printing process via fused deposition modeling. The prepared composites consist of modified poly(ethylene glycol) (PEG), lithium bis(trifluoromethylsulfonyl)imide (LiTFSI) and SiO₂-based nanofillers. PEG was successfully end group modified yielding telechelic PEG containing either ureidopyrimidone (UPy) or barbiturate moieties, capable to form supramolecular networks via hydrogen bonds, thus introducing self-healing to the electrolyte system. Silica nanoparticles (NPs) were used as a filler for further adjustment of mechanical properties of the electrolyte to enable 3D-printability. The surface functionalization of the NPs with either ionic liquid (IL) or hydrophobic alkyl chains is expected to lead to an improved dispersion of the NPs within the polymer matrix. Composites with different content of NPs (5%, 10%, 15%) and LiTFSI salt (EO/Li⁺ = 5, 10, 20) were analyzed via rheology for a better understanding of 3D printability, and via Broadband Dielectric Spectroscopy (BDS) for checking their ionic conductivity. The composite electrolyte PEG 1500 UPy₂/LiTFSI (EO:Li 5:1) mixed with 15% NP-IL was successfully 3D printed, revealing its suitability for application as printable composite electrolytes.

Action of Mechanical Forces on Polymerization and Polymers

In this review, we summarize recent developments in the field of the mechanochemistry of polymers. The aim of the review is to consider the consequences of mechanical forces and actions on polymers and polymer synthesis. First, we review classical works on chemical reactions and polymerization processes under strong shear deformations. Then, we analyze two emerging directions of research in mechanochemistry—the role of mechanophores and, for the first time, new physical phenomena, accompanying external impulse mechanical actions on polymers. Mechanophores have been recently proposed as sensors of fatigue and cracks in polymers and composites. The effects of the high-pressure pulsed loading of polymers and composites include the Dzyaloshinskii–Moriya effect, emission of superradiation and the formation of metal nanoparticles. These effects provide deeper insight into the mechanism of chemical reactions under shear deformations and pave the way for further research in the interests of modern technologies.

3D Printing of Solvent-Free Supramolecular Polymers

Additive manufacturing has significantly changed polymer science and technology by engineering complex material shapes and compositions. With the advent of dynamic properties in polymeric materials as a fundamental principle to achieve, e.g., self-healing properties, the use of supramolecular chemistry as a tool for molecular ordering has become important. By adjusting molecular nanoscopic (supramolecular) bonds in polymers, rheological properties, immanent for 3D printing, can be adjusted, resulting in shape persistence and improved printing. We here review recent progress in the 3D printing of supramolecular polymers, with a focus on fused deposition modelling (FDM) to overcome some of its limitations still being present up to date and open perspectives for their application.

Reversible regulation of metallo-base-pair interactions for DNA dehybridization by ultrasound

Mechanical force applied by ultrasound in solution leads to the dissociation of DNA metallo-base-pair interactions when these motifs are functionalized with oligodeoxynucleotide sequences of sufficient length. The annealing and force-induced denaturing process is followed by the attachment of distance-sensitive fluorescent probes and is found to be reversible.

Mechanochemical Release of Non-Covalently Bound Guests from a Polymer-Decorated Supramolecular Cage

Supramolecular coordination cages show a wide range of useful properties including, but not limited to, complex molecular machine-like operations, confined space catalysis, and rich host-guest chemistries. Here we report the uptake and release of non-covalently encapsulated, pharmaceutically-active cargo from an octahedral Pd cage bearing polymer chains on each vertex. Six poly(ethylene glycol)-decorated bipyridine ligands are used to assemble an octahedral PdII6 (TPT)4 cage. The supramolecular container encapsulates progesterone and ibuprofen within its hydrophobic nanocavity and is activated by shear force produced by ultrasonication in aqueous solution entailing complete cargo release upon rupture, as shown by NMR and GPC analyses.