Gold nanoparticles represent nanosized colloidal entities with high relevance for both basic and applied research. When gold nanoparticles are functionalized with polymer-molecule ligands, hybrid nanoparticles emerge whose interactions with the environment are controlled by the polymer coating layer: Colloidal stability and structure formation on the single particle level as well as at the supracolloidal scale can be enabled and engineered by tailoring the composition and architecture of this polymer coating. These possibilities in controlling structure formation may lead to synergistic and/or emergent functional properties of such hybrid colloidal systems. Eventually, the responsivity of the polymer coating to external triggers also enables the formation of hybrid supracolloidal systems with specific dynamic properties. This review provides an overview of fundamentals and recent developments in this vibrant domain of materials science.
- Klíčová slova
- end‐grafted polymers, gold nanoparticles, hybrid nanomaterials, nanostructure formation, responsive nanomaterials, self‐assembly, supracolloids,
- Publikační typ
- časopisecké články MeSH
- přehledy MeSH
Poly(2-(N,N-dimethylamino)ethyl acrylate) (PDMAEA) is a promising charge-shifting polycation with the capacity to form a range of morphologically distinct polyelectrolyte assemblies. Nevertheless, the basic character of the monomer and its hydrolytic instability impedes its controlled synthesis to higher molecular weight (MW). Herein, the reversible addition-fragmentation chain transfer polymerization of DMAEA is reported using a tert-butanol/V70 initiator/trithiocarbonate-based chain transfer agent (CTA) polymerization setup. The CTA instability is demonstrated in the presence of the unprotonated tertiary amino group of the DMAEA monomer, which limits the control over the conversion and MW of the polymer. In contrast, the shielding of the amino groups by their protonation leads to polymerization with high conversions and excellent control over MWs of polymer up to 100 000 g mol-1. Hydrolytic degradation study at pH values ranging from 5 to 9 reveals that both basic and protonated PDMAEA undergo a pH-dependent hydrolysis. The proposed polymerization conditions provide a means of synthesizing PDMAEA with well-controlled characteristics, which are beneficial for controlling the complexation processes during the formation of various polyelectrolyte assemblies.
- Klíčová slova
- DMAEA, RAFT polymerization, charge‐shifting polymer, hydrolysis, polycation,
- MeSH
- akryláty chemie MeSH
- hydrolýza MeSH
- koncentrace vodíkových iontů MeSH
- molekulární struktura MeSH
- molekulová hmotnost * MeSH
- nylony chemie chemická syntéza MeSH
- polymerizace * MeSH
- polymery chemie chemická syntéza MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- akryláty MeSH
- nylony MeSH
- polymery MeSH
Sound absorption plays a crucial role in addressing noise pollution that may cause harm to both human health and wildlife. To tackle this environmental issue, the implementation of natural-based sound absorbing materials attracts considerable attention in the last few years. In this study, sound absorbing, eco-friendly composites are produced by combining a 3D natural sponge namely Luffa Cylindrica (LC) with cellulose acetate (CA) microfibrous layers that are fabricated through electrospinning. Electrospun microfibers can effectively absorb sound waves due to their unique properties such as high porosity, small diameter, and large surface area. The individual components and the resulting composites, exhibiting various configurations, are characterized in respect to their morphology, porosity, density, and sound absorption properties. More precisely, the sound absorption coefficient is determined through the standing wave ratio method within the range of 500-4000 (Hz) frequency. The most promising materials consist of a multilayer combination of LC with CA microfibrous layers, which creates new prospects in the development of such materials for sound absorption applications.
- Klíčová slova
- Luffa Cylindrica, cellulose acetate fibers, electrospinning, sound absorption, standing wave ratio method,
- Publikační typ
- časopisecké články MeSH
The self-plasticization, i.e., the increase in the polymer chains' mobility by including its monomer, has a major impact on a polymer's structural, thermal, and mechanical properties. In this study, differential scanning calorimetry (DSC), optical and Raman microscopies, thermo-mechanical analysis (TMA), size exclusion chromatography equipped with a multi-angle light scattering detector (SEC-MALS), and X-ray diffraction analysis (XRD) are used to investigate the effect of thermally induced self-plasticization of poly-(p-dioxanone), PDX, on the crystal growths from the amorphous and molten states. Significant changes in the crystallization behavior and mechanical properties of PDX are found only for samples self-plasticized at the depolymerization temperature (Td) above 150 °C. The intense self-plasticization leads to the decrease of the crystallization temperature, increase of the crystal growth rapidity, disappearance of the distinct α→α' polymorphic transition, reduction of the overall melting temperature, and segregation of the redundant monomer. Although the morphology of the crystalline phase has a major impact on the mechanical properties of PDX, the self-plasticization itself does not seem to result in any major changes in the magnitude, localization, or morphology of formed crystallites (these are primarily driven by the temperature of crystal growth). The manifestation of the variable activation energy concept is discussed for the present crystallization data.
- Klíčová slova
- crystallization, depolymerization, differential scanning calorimetry, polydioxanone, self‐plasticization,
- MeSH
- diferenciální skenovací kalorimetrie MeSH
- difrakce rentgenového záření MeSH
- dioxany * chemie MeSH
- krystalizace * MeSH
- nízká teplota MeSH
- polymerizace * MeSH
- polymery * chemie MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- dioxany * MeSH
- poly-4-dioxan-2-one MeSH Prohlížeč
- polymery * MeSH
This study focuses on developing surface coatings with excellent antifouling properties, crucial for applications in the medical, biological, and technical fields, for materials and devices in direct contact with living tissues and bodily fluids such as blood. This approach combines thermoresponsive poly(2-alkyl-2-oxazoline)s, known for their inherent protein-repellent characteristics, with established antifouling motifs based on betaines. The polymer framework is constructed from various monomer types, including a novel benzophenone-modified 2-oxazoline for photocrosslinking and an azide-functionalized 2-oxazoline, allowing subsequent modification with alkyne-substituted antifouling motifs through copper(I)-catalyzed azide-alkyne cycloaddition. From these polymers surface-attached networks are created on benzophenone-modified gold substrates via photocrosslinking, resulting in hydrogel coatings with several micrometers thickness when swollen with aqueous media. Given that poly(2-alkyl-2-oxazoline)s can exhibit a lower critical solution temperature in water, their temperature-dependent solubility is compared to the swelling behavior of the surface-attached hydrogels upon thermal stimulation. The antifouling performance of these hydrogel coatings in contact with human blood plasma is further evaluated by surface plasmon resonance and optical waveguide spectroscopy. All surfaces demonstrate extremely low retention of blood plasma components, even with undiluted plasma. Notably, hydrogel layers with sulfobetaine moieties allow efficient penetration by plasma components, which can then be easily removed by rinsing with buffer.
- Klíčová slova
- SPR/OWS, antifouling thermoresponsive hydrogel coatings, betaines, blood plasma, photocrosslinkable poly(2-oxazoline)s,
- MeSH
- alkyny MeSH
- azidy * MeSH
- benzofenony MeSH
- hydrogely * chemie MeSH
- krevní plazma MeSH
- lidé MeSH
- polymery chemie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- alkyny MeSH
- azidy * MeSH
- benzofenony MeSH
- hydrogely * MeSH
- polymery MeSH
This study presents a systematic comparison of the antifouling properties of water-soluble poly(2-oxazoline) (PAOx) and poly(2-oxazine) (PAOzi) brushes grafted to gold surfaces. PAOx and PAOzi are emerging polymer classes in biomedical sciences and are being considered superior alternatives to widely used polyethylene glycol (PEG). Four different polymers, poly(2-methyl-2-oxazoline) (PMeOx), poly(2-ethyl-2-oxazoline) (PEtOx), poly(2-methyl-2-oxazine) (PMeOzi), and poly(2-ethyl-2-oxazine) (PEtOzi), each of them in three different chain lengths, are synthesized and characterized for their antifouling properties. Results show that all polymer-modified surfaces display better antifouling properties than bare gold surfaces as well as analogous PEG coatings. The antifouling properties increase in the following order: PEtOx < PMeOx ≈ PMeOzi < PEtOzi. The study suggests that the resistance to protein fouling derives from both surface hydrophilicity and the molecular structural flexibility of the polymer brushes. PEtOzi brushes with moderate hydrophilicity show the best antifouling performance, possibly due to their highest chain flexibility. Overall, the research contributes to the understanding of antifouling properties in PAOx and PAOzi polymers, with potential applications in various biomaterials.
- Klíčová slova
- antifouling coatings, poly(2-oxazine)s, poly(2-oxazoline)s, polymer brushes,
- MeSH
- bioznečištění * prevence a kontrola MeSH
- oxaziny chemie MeSH
- polyethylenglykoly chemie MeSH
- polymery * chemie MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- oxaziny MeSH
- poly(2-oxazoline) MeSH Prohlížeč
- polyethylenglykoly MeSH
- polymery * MeSH
A crucial component in designing soft actuating structures with controllable shape changes is programming internal, mismatching stresses. In this work, a new paradigm for achieving anisotropic dynamics between isotropic end-states-yielding a non-reciprocal shrinking/swelling response over a full actuation cycle-in a microscale actuator made of a single material, purely through microscale design is demonstrated. Anisotropic dynamics is achieved by incorporating micro-sized pores into certain segments of the structures; by arranging porous and non-porous segments (specifically, struts) into a 2D hexagonally-shaped microscopic poly(N-isopropyl acrylamide) hydrogel particle, the rate of isotropic shrinking/swelling in the structure is locally modulated, generating global anisotropic, non-reciprocal, dynamics. A simple mathematical model is introduced that reveals the physics that underlies these dynamics. This design has the potential to be used as a foundational tool for inducing non-reciprocal actuation cycles with a single material structure, and enables new possibilities in producing customized soft actuators and modular anisotropic metamaterials for a range of real-world applications, such as artificial cilia.
- Klíčová slova
- asymmetry, hydrogels, in-plane anisotropy, micro-actuators, non-reciprocity, soft robots,
- MeSH
- anizotropie MeSH
- hydrogely * MeSH
- poréznost MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- hydrogely * MeSH
New hyper-cross-linked porous organic polymers (POPs) with a high content of pyridine segments (7.86 mmol pyridine g-1 ), and a micro/mesoporous texture are reported. The networks are achieved by the chain-growth homopolymerization of 2,6- and 3,5-diethynylpyridines. The pyridine segments form links interconnecting the polyacetylene main chains in these networks. The content of pyridine segments in the networks can be tuned by copolymerizing diethynylpyridines with 1,3-diethynylbenzene. The pyridine rings in the networks serve as base and hydrophilic centers for the sorption of CO2 and water. The homopolymer pyridine networks are highly efficient in the low-pressure adsorption/desorption of CO2 . This sorption mode is promising for the postcombustion removal of CO2 from the fuel gas. The poly(3,5-diethynylpyridine) network exhibits high efficiency in capturing and releasing water vapor (determined capacity 376 mg g-1 at 298 K and relative humidity (RH) = 90% is one of the highest values reported for POPs) and is a promising material for the cyclic water harvesting from air. The reported networks are characterized by 13 C cross-polarization magic angle spinning NMR, thermogravimetric analysis, and N2 adsorption/desorption and their efficiency in CO2 and H2 O capturing is discussed in relation to the content and type of incorporated pyridine segments.
- Klíčová slova
- CO2 adsorption, hyper-cross-linked polymers, polyacetylenes, porous polymers, pyridine polymer networks, water adsorption, water harvesting,
- MeSH
- adsorpce MeSH
- oxid uhličitý * MeSH
- polymery * MeSH
- pyridiny MeSH
- voda MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- oxid uhličitý * MeSH
- polymery * MeSH
- pyridiny MeSH
- voda MeSH
Polypyrrole (PPy) is oxidatively polymerized in the frozen state at -24 °C in the presence of various organic dyes as morphology guiding agents in order to form homogeneous 1D PPy nanoforms. The freezing polymerization of pyrrole has a significant influence on the electrical conductivity and thermal stability but negligible influence on the yield compared to widely used room temperature polymerization.
- Klíčová slova
- conducting polymers, frozen polymerization, organic dyes, polypyrrole,
- MeSH
- elektrická vodivost MeSH
- polymerizace MeSH
- polymery * MeSH
- pyrroly * MeSH
- zmrazování MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- polymery * MeSH
- polypyrrole MeSH Prohlížeč
- pyrroly * MeSH
Herein, it is reported for the first time that when mixed with choline chloride, itaconic acid (IA), normally a low-reactive vinyl monomer, undergoes initiator-free radical polymerization under normal daylight. Furthermore, the process results in the formation of abnormally high-molecular-weight poly(itaconic acid) derivatives with Mw greater than ≈800 000 g mol-1 . Detailed 1D/2D NMR studies indicate that the polymers have two types of ionizable moieties, that is, anionic carboxylic and cationic choline ester groups in an average molar ratio of 12:1. Potentiometric titration shows polyampholyte behavior of the polymers. Tentative mechanistic studies reveal that the daylight-induced polymerization is initiated by species generated via interactions of near UV light with IA. However, EPR findings show that choline also participates in secondary radical reactions. The obtained polyampholytes are useful bio-based materials for fast and straightforward fabrication of polymer-clay nanocomposite hydrogels with excellent mechanical properties.
- Klíčová slova
- deep eutectic solvents, photopolymerization, polyampholytes, radical polymerization, renewable monomers,
- MeSH
- cholin chemie MeSH
- makromolekulární látky chemie MeSH
- molekulová hmotnost MeSH
- polymerizace účinky záření MeSH
- polymery chemická syntéza chemie MeSH
- sukcináty chemie MeSH
- světlo MeSH
- ultrafialové záření MeSH
- volné radikály chemie MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- cholin MeSH
- itaconic acid MeSH Prohlížeč
- makromolekulární látky MeSH
- polymery MeSH
- sukcináty MeSH
- volné radikály MeSH
