Guifu Si

Stimuli-responsive polymers are a class of functional materials that can undergo reversible physical or chemical changes in their structure, properties, or functions in response to external stimuli. In this work, we proposed a novel photoresponsive closed-loop polymer design strategy that integrates responsive molecular properties with the closed-loop concept, aiming to effectively address the long-standing challenges associated with the poor responsiveness and inadequate recyclability of traditional polymer materials. By combining the efficiency of ring-opening metathesis polymerization (ROMP) with the intrinsic thermal stability of photoresponsive molecular switches, we reported the (co)polymerization of photoresponsive diarylethene-based (DTE) cyclic monomers. This approach enables the rational design and preparation of photoresponsive polyolefins with tunable structures and properties, including mechanical performance, thermodynamic characteristics, and reversible color variation. We further explored equilibrium-controlled transformations to establish reversible closed-loop pathways for monomer–polymer interconversion. Notably, for the DTE-based homopolymer, a dual closed-loop platform was established via photoinduced transformation and Ru-catalyzed metathesis (de)polymerization. This work provides an efficient platform to advance the sustainable development and practical application of advanced responsive polymers.

随着塑料制品产量与消费量的持续攀升, 废弃塑料所带来的环境污染问题日益严峻, 已成为全球共同面临的迫切挑战. 在塑料回收过程中, 不同聚合物组分的高效分离仍是主要技术瓶颈之一. 多嵌段共聚物作为一种可诱导不同塑料相容的功能材料, 在混合塑料的高值化回收领域展现出巨大潜力, 但其广泛应用仍受限于复杂的合成工艺与结构调控难度. 本研究采用主链含烯烃双键反应位点的商用大分子单体与环烯烃单体共聚并经氢化处理, 成功制备了线性多嵌段聚合物材料. 该材料作为增容剂, 可显著改善混合塑料在机械回收过程中的分相问题, 使回收材料的拉伸韧性大幅提升. 此外, 该多嵌段聚合物也可用于调控聚烯烃表面性能, 有效增强其对水和油的阻隔能力. 本研究为混合塑料的高效资源化利用及聚烯烃材料改性提供了新的技术路径. 展现出广阔的应用前景.

Mechanical recycling is one of the simplest and most economical strategies to address ever-increasing plastic pollution, but it cannot be applied to immiscible mixed plastics and suffers from property deterioration after each cycle. By combining the amphiphilic block copolymer strategy and reactive compatibilization strategy, we designed a series of stapler strategies for compatibilizing/upcycling mixed plastics. First, various functionalized graft copolymers were accessed via different synthetic routes. Subsequently, the addition of a very small amount of stapler molecules induced a synergistic effect with the graft copolymers that improved the compatibility and mechanical properties of mixed plastics. These strategies were highly effective for various binary/ternary plastic systems and can be directly applied to postconsumer waste plastics, which can increase the toughness of mixed postconsumer waste plastics by 162 times. Most importantly, it also effectively improved the impact resistance, adhesion performance, and three-dimensional (3D) printing performance of mixed plastics, and permitted the recycling of plastic blends 20 times with minimal degradation in their mechanical properties.

Since polar groups can poison the metal centers in catalysts, the incorporation of polar comonomers usually comes at the expense of catalytic activity and polymer molecular weight. In this contribution, we demonstrate polar bimodal polyethylene as a potential solution to this trade-off. The more-polar/more-branched low-molecular-weight fraction provides polarity and processability, while the less-polar/less-branched high-molecular-weight fraction provides mechanical and melt properties. To achieve high miscibility between these two fractions, three synthetic routes are investigated: mixtures of homogeneous catalysts, separately supported heterogeneous catalysts, and a co-anchoring strategy (CAS) to heterogenize different homogeneous catalysts on one solid support. The CAS route is the only viable strategy for the synthesis of polar bimodal polyethylene with good molecular level entanglement and minimal phase separation. This produces polyolefin materials with excellent mechanical properties, surface/dyeing properties, gas barrier properties, as well as extrudability and 3D-printability.