Enrichment and Distribution of Pb2+ Ions in Zwitterionic Poly(cysteine methacrylate) Brushes at the Solid-Liquid Interface

Direct Measurements of Overlooked Long-Range Interactions near Zwitterionic and Nonionic Polymer Brushes

Current research on the antifouling mechanisms of "electrically neutral" polymer brushes predominantly emphasizes thermodynamically unfavorable short-range interactions. However, our study reveals the critical importance of long-range interactions. By utilizing zwitterionic poly(carboxybetaine methacrylate) (PCBMA) and nonionic poly[oligo(ethylene glycol) methyl ether methacrylate] (POEGMA) brushes as model systems, we employed total internal reflection microscopy (TIRM) to directly measure interactions with contaminants. Surprisingly, even seemingly neutral polymers exhibit significant electrostatic interactions with nearby contaminants─a fact that has been largely overlooked in this field. Our findings challenge the prevailing assumption of charge absence on surfaces grafted with antifouling polymer brushes and investigate how external stimuli (such as ionic strength and polymer conformation) affect these long-range interactions. In conclusion, this study presents a novel approach to exploring long-range interactions near polymer-grafted surfaces, offering valuable insights for the development of antifouling materials and biomedical applications in the future.

Pyroelectric Polyelectrolyte Brushes

Piezo- and pyroelectric materials are of interest, for example, for energy harvesting applications, for the development of tactile sensors, as well as neuromorphic computing. This study reports the observation of pyro- and piezoelectricity in thin surface-attached polymer brushes containing zwitterionic and electrolytic side groups that are prepared via surface-initiated polymerization. The pyro- and piezoelectric properties of the surface-grafted polyelectrolyte brushes are found to sensitively depend on and can be tuned by variation of the counterion. The observed piezo- and pyroelectric properties reflect the structural complexity of polymer brushes, and are attributed to a complex interplay of the non-uniform segment density within these films, together with a non-uniform distribution of counterions and specific ion effects. The fabrication of thin pyroelectric films by surface-initiated polymerization is an important addition to the existing strategies toward such materials. Surface-initiated polymerization, in particular, allows for facile grafting of polar thin polymer films from a wide range of substrates via a straightforward two-step protocol that obviates the need for multistep laborious synthetic procedures or thin film deposition protocols. The ability to produce polymer brushes with piezo- and pyroelectric properties opens up new avenues of application of these materials, for example, in energy harvesting or biosensing.

A combination of surface-initiated atom transfer radical polymerization and photo-initiated "thiol-ene" click chemistry: Fabrication of functionalized macroporous adsorption resins for enrichment of glycopeptides

A hydrophilic adsorbent (Cys@poly(AMA)@MAR) was successfully prepared for the enrichment of N-glycopeptides via surface-initiated atom transfer radical polymerization (SI-ATRP) and photo-initiated "thiol-ene" reaction using monodisperse macroporous adsorbent resin (MAR) as adsorption matrix. Due to the presence of electron-deficient acrylic groups and electron-rich vinyl groups in allyl methacrylate (AMA), both of them can participate in free radical reaction. Therefore, the polymerization time of SI-ATRP was optimized. The resulting poly(AMA)@MAR was modified with l-cysteine (L-Cys) via photo-initiated "thiol-ene" reaction, and the amount of vinyl retained was determined by measuring the adsorption of Cu²⁺. The Cys@poly(AMA)@MAR pendant brushes with high density of amine and carboxyl groups could capture N-glycopeptides from IgG digest and human serum digest by hydrophilic interaction. The 22 N-glycopeptides were identified from IgG digest and the limit of detection reached 10 fmol. The 319 N-glycosylation sites and 583 N-glycopeptides were identified from 2 μL human serum digest and mapped to 147 glycoproteins. It demonstrates great potential and commercialization prospects for the enrichment of N-glycopeptides.

Advanced Materials for Energy-Water Systems: The Central Role of Water/Solid Interfaces in Adsorption, Reactivity, and Transport

The structure, chemistry, and charge of interfaces between materials and aqueous fluids play a central role in determining properties and performance of numerous water systems. Sensors, membranes, sorbents, and heterogeneous catalysts almost uniformly rely on specific interactions between their surfaces and components dissolved or suspended in the water-and often the water molecules themselves-to detect and mitigate contaminants. Deleterious processes in these systems such as fouling, scaling (inorganic deposits), and corrosion are also governed by interfacial phenomena. Despite the importance of these interfaces, much remains to be learned about their multiscale interactions. Developing a deeper understanding of the molecular- and mesoscale phenomena at water/solid interfaces will be essential to driving innovation to address grand challenges in supplying sufficient fit-for-purpose water in the future. In this Review, we examine the current state of knowledge surrounding adsorption, reactivity, and transport in several key classes of water/solid interfaces, drawing on a synergistic combination of theory, simulation, and experiments, and provide an outlook for prioritizing strategic research directions.

Comparing Zwitterionic and PEG Exteriors of Polyelectrolyte Complex Micelles

A series of model polyelectrolyte complex micelles (PCMs) was prepared to investigate the consequences of neutral and zwitterionic chemistries and distinct charged cores on the size and stability of nanocarriers. Using aqueous reversible addition-fragmentation chain transfer (RAFT) polymerization, we synthesized a well-defined diblock polyelectrolyte system, poly(2-methacryloyloxyethyl phosphorylcholine methacrylate)-block-poly((vinylbenzyl) trimethylammonium) (PMPC-PVBTMA), at various neutral and charged block lengths to compare directly against PCM structure-property relationships centered on poly(ethylene glycol)-block-poly((vinylbenzyl) trimethylammonium) (PEG-PVBTMA) and poly(ethylene glycol)-block-poly(l-lysine) (PEG-PLK). After complexation with a common polyanion, poly(sodium acrylate), the resulting PCMs were characterized by dynamic light scattering (DLS) and small angle X-ray scattering (SAXS). We observed uniform assemblies of spherical micelles with a diameter ~1.5-2× larger when PMPC-PVBTMA was used compared to PEG-PLK and PEG-PVBTMA via SAXS and DLS. In addition, PEG-PLK PCMs proved most resistant to dissolution by both monovalent and divalent salt, followed by PEG-PVBTMA then PMPC-PVBTMA. All micelle systems were serum stable in 100% fetal bovine serum over the course of 8 h by time-resolved DLS, demonstrating minimal interactions with serum proteins and potential as in vivo drug delivery vehicles. This thorough study of the synthesis, assembly, and characterization of zwitterionic polymers in PCMs advances the design space for charge-driven micelle assemblies.