The Recent Advances of Polymer-POSS Nanocomposites With Low Dielectric Constant.

This study provides a comprehensive overview of the preparation methods for polyhedral oligomeric silsesquioxane (POSS) monomers and polymer/POSS nanocomposites. It focuses on the latest advancements in using POSS to design polymer nanocomposites with reduced dielectric constants. The study emphasizes exploring the potential of POSS, either alone or in combination with other materials, to decrease the dielectric constant and dielectric loss of various polymers, including polyimides, bismaleimide resins, poly(aryl ether)s, polybenzoxazines, benzocyclobutene resins, polyolefins, cyanate ester resins, and epoxy resins. In addition, the research investigates the impact of incorporating POSS on improving the thermal properties, mechanical properties, surface properties, and other aspects of these polymers. The entire study is divided into two parts, discussing systematically the role of POSS in reducing dielectric constants during the preparation of POSS composites using both physical blending and chemical synthesis methods. The goal of this research is to provide valuable strategies for designing a new generation of low dielectric constant materials suitable for large-scale integrated circuits in the semiconductor materials domain.

Polymeric Drug Delivery System Based on Pluronics for Cancer Treatment.

Pluronic polymers (pluronics) are a unique class of synthetic triblock copolymers containing hydrophobic polypropylene oxide (PPO) and hydrophilic polyethylene oxide (PEO) arranged in the PEO-PPO-PEO manner. Due to their excellent biocompatibility and amphiphilic properties, pluronics are an ideal and promising biological material, which is widely used in drug delivery, disease diagnosis, and treatment, among other applications. Through self-assembly or in combination with other materials, pluronics can form nano carriers with different morphologies, representing a kind of multifunctional pharmaceutical excipients. In recent years, the utilization of pluronic-based multi-functional drug carriers in tumor treatment has become widespread, and various responsive drug carriers are designed according to the characteristics of the tumor microenvironment, resulting in major progress in tumor therapy. This review introduces the specific role of pluronic-based polymer drug delivery systems in tumor therapy, focusing on their physical and chemical properties as well as the design aspects of pluronic polymers. Finally, using newer literature reports, this review provides insights into the future potential and challenges posed by different pluronic-based polymer drug delivery systems in tumor therapy.

Self-Healing Heterometallic Supramolecular Polymers Constructed by Hierarchical Assembly of Triply Orthogonal Interactions with Tunable Photophysical Properties.

Here, we present a method for the building of new bicyclic heterometallic cross-linked supramolecular polymers by hierarchical unification of three types of orthogonal noncovalent interactions, including platinum(II)-pyridine coordination-driven self-assembly, zinc-terpyridine complex, and host-guest interactions. The platinum-pyridine coordination provides the primary driving force to form discrete rhomboidal metallacycles. The assembly does not interfere with the zinc-terpyridine complexes, which link the discrete metallacycles into linear supramolecular polymers, and the conjugation length is extended upon the formation of the zinc-terpyridine complexes, which red-shifts the absorption and emission spectra. Finally, host-guest interactions via bis-ammonium salt binding to the benzo-21-crown-7 (B21C7) groups on the platinum acceptors afford the cross-linked supramolecular polymers. By continuous increase of the concentration of the supramolecular polymer to a relatively high level, supramolecular polymer gel is obtained, which exhibits self-healing properties and reversible gel-sol transitions stimulated by various external stimuli, including temperature, K+, and cyclen. Moreover, the photophysical properties of the supramolecular polymers could be effectively tuned by varying the substituents of the precursor ligands.

Metallacycle-Cored Supramolecular Polymers: Fluorescence Tuning by Variation of Substituents.

Herein, we present a method for the preparation of supramolecular polymers with tunable fluorescence via the combination of metal-ligand coordination and phenanthrene-21-crown-7 (P21C7)-based host-guest interactions. A suite of rhomboidal metallacycles with different substituents were prepared via the coordination-driven self-assembly of a P21C7-based 60° diplatinum(II) acceptor and 120° dipyridyl donors. Upon variation of the substituents on the dipyridyl donors, the metallacycles exhibit emission wavelengths spanning the visible region (λmax = 427-593 nm). Metallacycle-cored supramolecular polymers were obtained via host-guest interactions between bis-ammonium salts and P21C7. The supramolecular polymers exhibit emission wavelengths similar to those of the individual metallacycles and higher fluorescent efficiency in solution and thin films. Utilizing a yellow-emitting supramolecular polymer thin film with high quantum yield (0.22), a white-light-emitting LED was fabricated by painting the thin film onto an ultraviolet LED. This study presents an efficient approach for tuning the properties of fluorescent supramolecular polymers and the potential of the metallacycle-cored supramolecular polymers as a platform for the fabrication of light-emitting materials with good processability and tunability.

Metal Coordination Stoichiometry Controlled Formation of Linear and Hyperbranched Supramolecular Polymers.

Controlling the topologies of polymers is a hot topic in polymer chemistry because the physical and/or chemical properties of polymers are determined (at least partially) by their topologies. This study exploits the host-guest interactions between dibenzo-24-crown-8 and secondary ammonium salts and metal coordination interactions between 2,6-bis(benzimidazolyl)-pyridine units with metal ions (Zn(II) and/or Eu(III) ) as orthogonal non-covalent interactions to prepare supramolecular polymers. By changing the ratios of the metal ion additives (Zn(NO3 )2 and Eu(NO3 )3 ) linkers to join the host-guest dimeric complex, the linear supramolecular polymers (100 mol% Zn(NO3 )2 per ligand) and hyperbranched supramolecular polymers (97 mol% Zn(NO3 )2 and 3 mol% Eu(NO3 )3 per ligand) are separately and successfully constructed. This approach not only expands topological control over polymeric systems, but also paves the way for the functionalization of smart and adaptive materials.

A multiple-responsive self-healing supramolecular polymer gel network based on multiple orthogonal interactions.

Supramolecular polymer networks have attracted considerable attention not only due to their topological importance but also because they can show some fantastic properties such as stimuli-responsiveness and self-healing. Although various supramolecular networks are constructed by supramolecular chemists based on different non-covalent interactions, supramolecular polymer networks based on multiple orthogonal interactions are still rare. Here, a supramolecular polymer network is presented on the basis of the host-guest interactions between dibenzo-24-crown-8 (DB24C8) and dibenzylammonium salts (DBAS), the metal-ligand coordination interactions between terpyridine and Zn(OTf)2 , and between 1,2,3-triazole and PdCl2 (PhCN)2 . The topology of the networks can be easily tuned from monomer to main-chain supramolecular polymer and then to the supramolecular networks. This process is well studied by various characterization methods such as (1) H NMR, UV-vis, DOSY, viscosity, and rheological measurements. More importantly, a supramolecular gel is obtained at high concentrations of the supramolecular networks, which demonstrates both stimuli-responsiveness and self-healing properties.

A fully substituted 3-silolene functions as promising building block for hyperbranched poly(silylenevinylene).

A 3-silolene derivative, 2,2,5,5-tetrakis(dimethylsilyl)-1,1-dimethyl-3,4-diphenyl-3-silolene (TDMSHS), is first synthesized and characterized by X-ray diffraction crystallography and spectroscopic methods. Hydrosilylation polymerization of TDMSHS with 1,1-dimethyl-2,5-bis(4-ethynylphenyl)-3,4-diphenylsilole in the presence of Karstedt's catalyst generates a stereoregular silole-containing hyperbranched poly(silylenevinylene) (hb-SPSV) with a high molecular weight (M(w) = 146,000, M(w)/M(n) = 1.5) in high yield (≈95%). hb-SPSV exhibits excellent thermal stability and strong fluorescence, and the emission of its aggregates in aqueous mixture can be quenched efficiently by picric acid with large quenching constants K(SV) up to 414400 M(-1).

Self-Healing Metallacycle-Cored Supramolecular Polymers Based on a Metal-Salen Complex Constructed by Orthogonal Metal Coordination and Host-Guest Interaction with Amino Acid Sensing.

A platinum(II) metallacycle-cored supramolecular network based on a metal-salen complex was successfully constructed by two orthogonal noncovalent interactions (host-guest interactions and metal coordination interactions). The obtained metallo-supramolecular polymer could further form gels when the concentration of metallacycle 1 was 160.0 mM. This gel exhibited multiple stimuli-responsive gel-sol phase transitions under different stimuli, such as temperature, competitive guests, etc. Moreover, it exhibited good self-healing properties and could be used as a turn-off sensor for thiol-containing amino acids.

Lyotropic liquid-crystalline phases formed by Pluronic P123 in ethylammonium nitrate.

Aggregation of poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) triblock copolymer, Pluronic P123, is promoted in a room temperature ionic liquid, ethylammonium nitrate (EAN). A series of lyotropic mesophases including normal micellar cubic (I1), normal hexagonal (H1), lamellar (Lalpha), and reverse bicontinuous cubic (V2) are identified at 25 degrees C by using polarized optical microscopy and small-angle X-ray scattering techniques. Such self-assembly behavior of P123 in EAN is similar to those observed in H2O or 1-n-butyl-3-methylimidazolium hexafluorophosphate ([BMim(+)][PF6(-)]) systems except for the presence of the V2 phase in EAN and the absence of the I 1 phase in [BMim(+)][PF6(-)]. This suggests that the ionic solvent of EAN plays similar roles as H2O and [BMim(+)][PF6(-)] during the aggregation process and solvates the PEO blocks through hydrogen-bond interaction. Furthermore, the hydrogen bonds are considered to form between the ethylammonium cations and oxygen atoms of the PEO blocks as confirmed by Fourier transform infrared spectra of P123-EAN assemblies. This deduction is also consistent with the results from differential scanning calorimetry and thermogravimetric analysis. The additional V2 phase appearing in the P123-EAN system is attributed to the higher affinity for the relatively hydrophobic PPO blocks to EAN than to water, which might reduce the effective area of the solvophilic headgroup and increase the volume of the solvophobic part. The obtained results may help us to better understand the self-assembly process for amphiphilic block copolymers in protic solvents.