Polymers have evolved to become much more than plastics. This is especially true for polymers or copolymers that respond to external stimuli and have accordingly found increased attention across several disciplines and play a significant role in advancing materials sciences. Probably the most well-known responsive polymer is poly(N-isopropoyl acrylamide) (PNIPAM), which demonstrates a lower critical solution temperature and has become the lead material for a versatile and vibrant field in polymer science. The success and utility of PNIPAM has triggered the search for new stimuli-responsive—“smart”—polymers that respond to temperature, pH-changes, gases, light, redox, salts, mechanical stress, electric or magnetic fields, etc.

With a plethora of controlled and living polymerization techniques and creative approaches to post-polymerization modification, functional polymers are now accessible which allow the combination of several responsive groups to generate new examples of multi-responsive materials.

This special issue collects 19 recent developments in the area of stimuli-responsive polymers. Contributions by authors with interdisciplinary backgrounds have been collected to feature synthesis of new polymers, polymer surfaces, or detailed physico-chemical analyses of stimuli-responsive polymers to elucidate their potential in a variety of applications. The special issue contains two review articles: Marek W. Urban and co-workers summarize developments in commodity acrylics, epoxies, esters, carbonates, urethanes, and siloxane-based polymers containing responsive elements (2100054). Lei Tao and colleagues review recent advances in multifunctional phenylboronic acid-containing polymers as responsive materials (2100022).

Two contributions update the classic example of PNIPAM. Jianbo Tan and co-workers used PNIPAM in an innovative photo-PISA approach (i.e., polymerization-induced self-assembly) to prepare PNIPAM-based block copolymer assemblies (2100201); and Nathanial Corrigan and co-workers presented interesting data on the molar mass distribution on the phase-change temperature of PNIPAM (2100212). Other contributions expand the field of thermoresponsive polymers. Takaya Terashima et al. developed a cation-templated synthesis towards large in-chain ring cyclopolymers that are examples of thermoresponsive pseudo-crown ether polymers (2000670). Zhengbiao Zhang and co-workers present sequence-dependent stimuli-response in PNIPAM copolymers using 2,5-dimethylfuran/acrylonitrile adduct as a latent monomer (2000724).

Longhai Guo and colleagues prepared ABA-triblock copolymers containing thermoresponsive moieties that demonstrated an ice recrystallization inhibition activity, resulting in decreased sizes of ice crystals (2100024). Gas-responsive assemblies based on amphiphilic block copolymers were prepared by San H. Thang and co-workers; these materials showed a morphological transition from nanotubes to vesicles under gas stimulation mimicking the function of alveoli (2100019).

Dominik Konkolewicz and co-workers presented covalent adaptable networks (CANs) with dynamic properties (2100070). Because of the reversible linkages in the CANs, temperature-responsive re-healing and malleability were achieved. In addition, photoresponsive coumarin-containing CANs revealed light-mediated reconfigurability. Mechanically enhanced hydrogels are reported by Yang Li et al. (2100028). Masami Kamigaito and co-workers prepared copolymers containing poly(thioether)s and poly(vinylether)s, which self-assembled in aqueous solutions and exhibited lower critical solution temperatures that depend on the segment sequences and lengths (2100192).

Photoresponsive polymer vesicles are presented by Jinming Hu and co-workers which enabled the sequential release of nitric oxide and gentamicin to eradicate biofilms (2000759), while Richard Hoogenboom and his colleagues synthesised copolymers with responsive host–guest complexation using 1,5-dialkoxynaphthalene guest molecules and cyclobis(paraquat-p-phenylene) tetrachloride hosts to manipulate the copolymer phase transition temperature (2100068).

Stimuli-responsive polymers can also be attached to surfaces to control interfacial properties. In our collection, Karen Lienkamp and her colleagues developed surface-attached hydrophobically modified poly(carboxybetaine)s, which change from a protein-repellent polyzwitterion to antimicrobial and protein-adhesive polycations upon pH-change (2100051). Cyrille Boyer and co-workers present polymeric brushes with antifouling and visible light-activated bactericidal properties using surface-initiated photoinduced electron transfer-reversible addition-fragmentation chain transfer polymerization (SI-PET-RAFT) (2100106). Didier Gigmes et al. grafted photoresponsive polystyrene on silica nanoparticles using ortho-nitrobenzyl linkers (2100181).

Jian Zhu and co-workers polymerized (p-phenylseleno) styrene to obtain polymers that were selectively oxidized to selenoxide or selenone groups by H₂O₂ or NaClO (2000764), and Birgit Esser and co-workers demonstrated the potential of dibenzo[a,e]cyclooctatetraene-containing polymers as battery electrode materials, which show pseudo capacitive behaviour with Faradaic contributions (2000725). Zi-Chen Li and colleagues report on the design and synthesis of a fluoride-triggered self-immolative polyester (2100169).

In summary, this special issue is a reminder that the long-standing field of stimuli-responsive polymers continues to evolve at a rapid pace. New developments in synthesis, characterization, and processing continue to enable creative advances that pave the way for fundamental science to be applied to materials with real-world utility. We are proud to present this collection of exciting developments, and we hope that the resulting knowledge will inspire further expansion of a thriving field.

聚合物的发展已经远远超过塑料。对于对外部刺激做出反应的聚合物或共聚物尤其如此，因此在多个学科中受到越来越多的关注，并在推进材料科学方面发挥着重要作用。可能最著名的响应性聚合物是聚（N-异丙基丙烯酰胺）（PNIPAM），它具有较低的临界溶解温度，并已成为聚合物科学中多功能和充满活力的领域的主要材料。PNIPAM 的成功和实用性引发了对新的刺激响应性——“智能”——聚合物的探索，这些聚合物对温度、pH 值变化、气体、光、氧化还原、盐、机械应力、电场或磁场等做出响应。

借助大量受控和活性聚合技术以及聚合后改性的创造性方法，现在可以使用功能聚合物，这些聚合物允许多个响应基团的组合以生成多响应材料的新实例。

本期特刊收集了刺激响应聚合物领域的 19 项最新进展。已经收集了具有跨学科背景的作者的贡献，以合成新聚合物、聚合物表面或刺激响应聚合物的详细物理化学分析，以阐明它们在各种应用中的潜力。本期特刊包含两篇评论文章：Marek W. Urban 及其同事总结了商品丙烯酸、环氧树脂、酯、碳酸酯、氨基甲酸酯和含有响应元素的硅氧烷基聚合物的发展 (2100054)。Lei Tao 及其同事回顾了含多功能苯基硼酸聚合物作为响应材料的最新进展 (2100022)。

两个贡献更新了 PNIPAM 的经典示例。谭建波及其同事在创新的 photo-PISA 方法（即聚合诱导自组装）中使用 PNIPAM 制备了基于 PNIPAM 的嵌段共聚物组件 (2100201)；和 Nathanial Corrigan 及其同事提供了有关 PNIPAM (2100212) 相变温度的摩尔质量分布的有趣数据。其他贡献扩展了热敏聚合物的领域。Takaya Terashima 等。开发了一种针对大型链内环环聚合物的阳离子模板合成，这些环聚合物是热响应性假冠醚聚合物的例子 (2000670)。Zhengbiao Zhang 和同事使用 2,5-二甲基呋喃/丙烯腈加合物作为潜在单体 (2000724) 展示了 PNIPAM 共聚物中的序列依赖性刺激响应。

Longhai Guo 及其同事制备了含有热响应部分的 ABA-三嵌段共聚物，显示出冰重结晶抑制活性，导致冰晶尺寸减小 (2100024)。基于两亲性嵌段共聚物的气体响应组件由 San H. Thang 及其同事制备；这些材料在模拟肺泡功能的气体刺激下显示出从纳米管到囊泡的形态转变 (2100019)。

Dominik Konkolewicz 及其同事提出了具有动态特性的共价自适应网络 (CAN) (2100070)。由于 CAN 中的可逆连接，实现了温度响应再愈合和延展性。此外，含有光响应香豆素的 CAN 显示出光介导的可重构性。Yang Li 等人报道了机械增强的水凝胶。(2100028)。Masami Kamigaito 及其同事制备了含有聚（硫醚）和聚（乙烯基醚）的共聚物，它们在水溶液中自组装并表现出较低的临界溶液温度，这取决于链段序列和长度 (2100192)。

Jinming Hu 及其同事提出了光响应聚合物囊泡，它能够连续释放一氧化氮和庆大霉素以根除生物膜 (2000759)，而 Richard Hoogenboom 及其同事使用 1,5-二烷氧基萘客体合成了具有响应性主客体络合的共聚物分子和环双（百草枯-对亚苯基）四氯化物主体来控制共聚物相变温度 (2100068)。

刺激响应聚合物也可以附着在表面上以控制界面特性。在我们的系列中，Karen Lienkamp 和她的同事开发了表面附着的疏水改性聚（羧基甜菜碱），它在 pH 值变化时从抗蛋白质的聚两性离子变为具有抗菌性和蛋白质粘附性的聚阳离子 (2100051)。Cyrille Boyer 及其同事使用表面引发的光诱导电子转移可逆加成断裂链转移聚合 (SI-PET-RAFT) (2100106) 展示了具有防污和可见光活化杀菌特性的聚合物刷子。迪迪埃·吉格姆斯等人。使用邻硝基苄基接头在二氧化硅纳米粒子上接枝光响应聚苯乙烯 (2100181)。

朱健及其同事聚合（对苯硒基）苯乙烯获得聚合物，该聚合物被 H ₂ O ₂ 或 NaClO (2000764)选择性氧化为硒氧化物或硒酮基团，Birgit Esser 及其同事证明了二苯并[ a]的潜力。, e ] 含环辛四烯的聚合物作为电池电极材料，显示出具有法拉第贡献的伪电容行为 (2000725)。Zi-Chen Li 及其同事报告了一种氟化物触发的自焚聚酯 (2100169) 的设计和合成。

总之，本期特刊提醒人们，刺激响应聚合物这一长期存在的领域正在继续快速发展。合成、表征和加工方面的新发展继续推动创造性进步，为将基础科学应用于具有现实世界效用的材料铺平道路。我们很自豪地展示了这一系列令人兴奋的发展，我们希望由此产生的知识将激发蓬勃发展的领域的进一步扩展。