Reversible Switching and Recycling of Thermoresponsive 1,2,4-Triazolium-Based Poly(ionic liquid) Catalysts for Porous Organic Cage Synthesis in Organic Media

Homogeneous catalysts of high activity and selectivity often face challenges in the separation from feedstocks and products after reactions. In contrast, heterogeneous catalysts are easier to separate, usually at the cost of compromised catalytic performance. By designing catalysts capable of switching between homogeneous and heterogeneous states for catalysis and separation, the merits of both could be synergistically combined. In this study, a thermoresponsive 1,2,4-triazolium-based poly(ionic liquid) (PIL) was applied as a temperature-switchable organocatalyst for the controlled synthesis of porous organic cages in methanol. Variation of the reaction temperature induced a phase transition of the PIL, causing the polymer chains to dissolve or collapse in methanol, thereby exposing or shielding the catalytically active sites to proceed or retard the reaction, respectively. To note, at a sufficiently low temperature, the PIL as a catalyst precipitated out of its methanol solution and could be separated by centrifugation or filtration for reuse, similar to common heterogeneous catalysts. Such switchable and recyclable properties of polymeric catalysts will inspire the design of efficient and adaptable organic or hybrid nanoreactors in liquid media.

Tumor microenvironment-responsive hyperbranched polymers for controlled drug delivery

Hyperbranched polymers (HBPs) have drawn great interest in the biomedical field on account of their special morphology, low viscosity, self-regulation, and facile preparation methods. Moreover, their large intramolecular cavities, high biocompatibility, biodegradability, and targeting properties render them very suitable for anti-tumor drug delivery. Recently, exploiting the specific characteristics of the tumor microenvironment, a range of multifunctional HBPs responsive to the tumor microenvironment have emerged. By further introducing various types of drugs through physical embedding or chemical coupling, the resulting HBPs based delivery systems have played a crucial part in improving drug stability, increasing effective drug concentration, decreasing drug toxicity and side effects, and enhancing anti-tumor effect. Here, based on different types of tumor microenvironment stimulation signals such as pH, redox, temperature, etc., we systematically review the preparation and response mechanism of HBPs, summarize the latest advances in drug delivery applications, and analyze the challenges and future research directions for such nanomaterials in biomedical clinical applications.

BODIPY based hyperbranched conjugated polymers for detecting organic vapors

BODIPY-based hyperbranched polymer showed improved selectivity and sensitivity for toluene as originated from the strong π–π interaction and high porosity within polymer matrix.