Side-chain Polymers Research Articles

Influence of Polymer Side Chain Size and Backbone Length on the Self-Assembly of Supramolecular Polymer Bottlebrushes.

Hydrogen bonds are a versatile tool for creating fibrous, bottlebrush-like assemblies of polymeric building blocks. However, a delicate balance of forces exists between the steric repulsion of the polymer chains and these directed supramolecular forces. In this work we have systematically investigated the influence of structural parameters of the attached polymers on the assembly behaviour of benzene trisurea (BTU) and benzene tris(phenylalanine) (BTP) conjugates in water. Polymers with increasing main chain lengths and different side chain sizes were prepared by reversible addition-fragmentation chain-transfer (RAFT) polymerization of hydroxyethyl acrylate (HEA), tri(ethylene glycol) methyl ether acrylate (TEGA) and oligo(ethylene glycol) methyl ether acrylate (OEGA). The resulting structures were analyzed using small angle X-ray scattering (SAXS) and transmission electron microscopy (TEM). Both BTU and BTP formed fibres with PHEA attached, but a transition to spherical morphologies was observed at degrees of polymerisation (DP) of 70 and above. Overall, the main chain length appeared to be a dominating factor in inducing morphology transitions. Increasing the side chain size generally had a similar effect but mainly impeded any aggregation as is the case of POEGA. Interestingly, BTP conjugates still formed fibres, suggesting that the stronger intermolecular interactions can compensate partially for the steric repulsion.

Volume compensating materials after vapor phase infiltration: effect of different butyl isomers of polymer side-chains on high process temperature durability

Vapor phase infiltration is a facile process that adds metallic features to organic polymer patterns. Generally, volume expansion in typical polymers such as poly(methyl methacrylate) (PMMA) is observed after metal infiltration, which limits the application of this technique in nanofabrication processes. In this study, poly(sec-butyl methacrylate) P(sBuMA) and poly(iso-butyl methacrylate) P(iBuMA) with leaving groups were selected as alternatives for PMMA and poly(tert-butyl methacrylate) P(tBuMA), and their aluminum (Al) infiltration behaviors were investigated. Notably, Al species infiltrated into P(sBuMA) and P(iBuMA) at 200 °C, whereas no Al infiltration was observed at 100 °C. Volume shrinkage was observed for both polymers after infiltration. This shows that the volume change in the base material after metal infiltration can be minimized by combining a conventional volume-expanding polymer, such as PMMA, with volume-shrinking polymers with high process temperature durability.

Conjugated Polymers with Self-Immolative Sidechain Linkers for Carbon Nanotube Dispersion.

Single-walled carbon nanotubes (SWNTs) are promising materials for generating high-performance electronic devices. However, these applications are greatly restricted by their lack of purity and solubility. Commercially available SWNTs are a mixture of semi-conducting (sc-) and metallic (m-) SWNTs and are insoluble in common solvents. Conjugated polymers can selectively disperse either sc- or m-SWNTs and increase their solubility; however, the conductivity of conjugated polymer-wrapped SWNTs is largely affected by the polymer side chains. Here, a poly(fluorene-co-phenylene) polymer that contains a self-immolative linker as part of its sidechains is reported. The self-immolative linker is stabilized with a tert-butyldimethylsilyl ether group that, upon treatment with tetra-n-butylammonium fluoride (TBAF), undergoes a 1,6-elimination reaction to release the sidechain. Sonication of this polymer with SWNTs in tetrahydrofuran (THF) results in concentrated dispersions that are used to prepare polymer-SWNT thin films. Treatment with TBAF caused side-chain cleavage into carbon dioxide and the corresponding diol, which can be easily removed by washing with solvent. This process is characterized by a combination of absorption and Raman spectroscopy, as well as four-point probe measurements. The conductance of the SWNT thin films increased ≈60-fold upon simple TBAF treatment, opening new possibilities for producing high-conductivity SWNT materials for numerous applications.

Investigating the effect of anchoring groups modified comb-like polycarboxylate hyperdispersants on dispersion and stability in dispersed dyes

Comb-like hyperdispersants are widely used for the dispersion of liquid dispersed dyes (LDDs), because of the molecular structure of comb, in which the effective steric hindrance effects provided by polymer side chains and the adsorption force provided by anchoring groups, resulting in the dispersant to be firmly adsorbed on the surface of the dye. However, the mechanism by which the anchoring groups in this dispersant affect the dispersion and stability of LDDs is still unclear. Herein, three types of anchoring group modified comb-like polycarboxylate hyperdispersants were synthesized to explore the effect of anchoring groups on stability and dispersibility, in which the anchoring groups from the monomers of 2-vinylnaphthalene (2-VNP), styrene (St), and 4-vinylbiphenyl (4-VBP). The optimal sand grinding conditions and dispersion stability of the modified hyperdispersants were comprehensively investigated. 2-VNP modified hyperdispersant (DPN) possessed higher grinding efficiency and better dispersion stability than those of St (DPS) and 4-VBP modified hyperdispersants (DPB). The results of atomic force microscope (AFM) and quartz crystal microbalance (QCM) indicated that DPN exhibited higher adsorption force (2.16 mN/m) than that the DPS (0.648 mN/m) and DPB (1.56 mN/m), thereby improving the adsorption strength of dispersants and DDs, stabling the dispersion effect of LDDs. In addition, the dyeing performance of the prepared LDDs on polyester fabric was further investigated. It was found that these LDDs acquired a faster dyeing rate, higher K/S values and rubbing color fastness, and lower chemical oxygen demand (COD) of residual liquid than commercial powder DDs, due to the higher adsorption force on the DDs surface provided good colloidal stability in the high temperatures dye bath. We expect that this study will provide important mechanistic insights into the development of hyperdispersants for LDDs controlled by high adsorption force anchoring groups.

Skin Temperature-Triggered Switchable Adhesive Coatings for Wearing Comfortable Epidermal Electronics

Smart adhesives with switchable adhesion strength on demand are crucial for ensuring the stability of the epidermal electronics-skin interface and preventing skin damage caused by device detachment. However, challenges such as harsh triggering conditions, lack of precise control over material comprehensive performance, and difficulty in achieving micron-level controlled integration of materials on device surfaces hinder the application of switchable adhesives in epidermal electronics. Herein, we designed a coatable, thermally-triggered switchable adhesive that has a high adhesion of 68.8 N/m at skin temperature, e.g., 33 °C, and after a slight cooling, e.g., 20 °C, the adhesion decreases to 6.59 N/m, resulting in a high switching ratio of 10.4. The switching time is < 1 min. This unique property is achieved by combining side-chain crystalline polymers and self-adhesive polymers through a strategy of constructing core–shell particles. The results of thermal analyses, rheology, and solid-state nuclear magnetic resonance indicate that a rapid and reversible crystallization-melting transition within the material is the essence of the adhesion switching. By depositing the material on flexible electrodes using spraying technology, we have obtained an ultra-thin (<5 μm), and peelable on-demand epidermal electrode, demonstrating the advantages of emulsion materials in the fabrication of wearing comfortable devices.

Amyloid β-Peptide Segment Conjugated Side-Chain Proline-Based Polymers as Potent Inhibitors in Lysozyme Amyloidosis.

Developing effective amyloidosis inhibitors poses a significant challenge due to the dynamic nature of the protein structures, the complex interplay of interfaces in protein-protein interactions, and the irreversible nature of amyloid assembly. The interactions of amyloidogenic polypeptides with other peptides play a pivotal role in modulating amyloidosis and fibril formation. This study presents a novel approach for designing and synthesizing amyloid interaction surfaces using segments derived from the amyloid-promoting sequence of amyloid β-peptide [VF(Aβ(18-19)/FF(Aβ(19-20)/LVF(Aβ(17-19)/LVFF(Aβ(17-20)], where VF, FF, LVF and LVFF stands for valine phenylalanine dipeptide, phenylalanine phenylalanine dipeptide, leucine valine phenylalanine tripeptide and leucine valine phenylalanine phenylalanine tetrapeptide, respectively. These segments are conjugated with side-chain proline-based methacrylate polymers serving as potent lysozyme amyloidosis inhibitors and demonstrating reduced cytotoxicity of amyloid aggregations. Di-, tri-, and tetra-peptide conjugated chain transfer agents (CTAs) were synthesized and used for the reversible addition-fragmentation chain transfer polymerization of tert-butoxycarbonyl (Boc)-proline methacryloyloxyethyl ester (Boc-Pro-HEMA). Deprotection of Boc-groups from the side-chain proline pendants resulted in water-soluble polymers with defined peptide chain ends as peptide-polymer bioconjugates. Among them, the LVFF-conjugated polymer acted as a potent inhibitor with significantly suppressed lysozyme amyloidosis, a finding supported by comprehensive spectroscopic, microscopic, and computational analyses. These results unveil the synergistic effect between the segment-derived amyloid β-peptide and side-chain proline-based polymers, offering new prospects for targeting lysozyme amyloidosis.

Pressure-Induced Amidine Formation via Side-Chain Polymerization in a Charge-Transfer Cocrystal.

Compression of small molecules can induce solid-state reactions that are difficult or impossible under conventional, solution-phase conditions. Of particular interest is the topochemical-like reaction of arenes to produce polymeric nanomaterials. However, high reaction onset pressures and poor selectivity remain significant challenges. Herein, the incorporation of electron-withdrawing and -donating groups into π-stacked arenes is proposed as a strategy to reduce reaction barriers to cycloaddition and onset pressures. Nevertheless, competing side-chain reactions between functional groups represent alternative viable pathways. For the case of a diaminobenzene:tetracyanobenzene cocrystal, amidine formation between amine and cyano groups occurs prior to cycloaddition with an onset pressure near 9 GPa, as determined using vibrational spectroscopy, X-ray diffraction, and first-principles calculations. This work demonstrates that reduced-barrier cycloaddition reactions are theoretically possible via strategic functionalization; however, the incorporation of pendant groups may enable alternative reaction pathways. Controlled reactions between pendant groups represent an additional strategy for producing unique polymeric nanomaterials.

Liquid crystallinity and magnetorheological performance of polymeric liquid crystal magnetic composites

ABSTRACT Magnetorheological fluids (MRF) are regarded as a novel ‘intelligent’ material because they show the ability to respond to external stimuli. However, with the extension of working time, the agglomeration and sedimentation of magnetic particles become a serious problem, which has a great impact on the magnetorheological performance. Many methods have been proposed to overcome the particle settling problem, including magnetic particle modification and carrier liquid modification, but they all show negative effects on the magnetorheological performance of MRF. A new method to prepare the magnetic liquid crystal (LC) composites [PEA-COOH]SO3H@Fe3O4 series, with Fe3O4 nanoparticles as core and side-chain supramolecular LC polymers with different mesogen contents as coating, were reported. The chemical structure, magnetic property and LC properties were investigated by a variety of techniques. In order to study the effects of the mesogen content and LC phase state of magnetic LC composites on magnetorheological performance and sedimentation stability, MRF based on silicone oil carrier liquid and [PEA-COOH]SO3H@Fe3O4 dispersed phase were prepared. It was found that dynamic yield stress, plastic viscosity and the sedimentation ratio increased slightly with increasing mesogen content in the magnetic LC composites. What’s more, MRF prepared by magnetic LC composites annealed in LC state exhibited better magnetorheological performance and sedimentation stability than those in glassy state and isotropic state. These results indicated that the synergetic effects of LC orientation and magnetic field-induced arrangement of Fe3O4 magnetic particles can improve the magnetorheological performance and sedimentation stability of MRF.

Local Structure of Atactic Polystyrene Investigated by Molecular Dynamics Method

Molecular dynamics computer simulation of three substances ethylbenzene (EB), pentastyrene (PS-5), and polystyrene-25 (PS-25) was performed to investigate the local order of the phenyl rings in monomers and side-chain polymers. Monomer molecules (EB) tend to be in T-configuration, which corresponds to isotropic local structure. Phenyl rings in chained molecules PS-5 and PS-25 partly cooperate in both parallel-displaced and “sandwich” configuration with π–π stacking. These configurations are locally anisotropic and lead to the increasing of Kerr constant K. Analysis of the local structure was performed by calculating the cylindrical distribution function.

All-Atom Molecular Dynamics Simulations of Uncharged Linear Polymer Bottlebrushes: Effect of the Brush Sizes and the Number of Side-Chain Monomers.

Bottlebrush polymers (BBPs), characterized by grafted polymer side chains on linear backbone polymer chain, have emerged as a unique and versatile class of macromolecules with extensive applications in the fields of material science, electronics, battery materials, self-healing technology, etc. In this paper, we employ all-atom molecular dynamics (MD) simulations to present a comprehensive study of poly(methyl methacrylate)-g-poly(2-ethyl-2-oxazoline) (PMMA-g-PEtOx) BBP and its structural and hydration properties for varying number of backbone monomers (NBB) and side chain monomers (NSC), as well as properties of water molecules supported by the BBP. We find that the radius of gyration follows a scaling of Rg ∼NSC0.36 for smaller grafts and Rg ∼ NSC0.52-0.58 for longer grafts. We also find that the overall shape of the bottlebrush goes from a rod to sphere-like shape with the increase in NSC. Both the hydration per side chain monomer and hydrogen bonds (HBs) per oxygen and nitrogen of the side chain monomer reduce with an increase in NSC, caused by a corresponding enhancement in localization of the side chain monomers in the interior of the BBP. Furthermore, steric influences ensure the number of water-oxygen HBs is much more than the number of water-nitrogen HBs (with oxygen and nitrogen atoms belonging to the monomer side chains). Also, the BBP-supported water molecules demonstrate two distinctly ordered domains with one more structured and one less structured. The more structured domain disappears with an increase in NSC that causes more side chain monomers to localize in the interior of the BBPs. Finally, we observe that despite the highly negative partial charges of the oxygen and nitrogen atoms (of the side chain monomers), the dipole orientation distributions of water molecules around these atoms exhibit the presence of a neutral environment rather than an anionic environment. Overall, we anticipate that our study will generate significant interest in probing the various BBP systems in greater atomistic detail.

Synthesis and post‐polymerization modification of poly(diglycidyl fumarate)s and their thermal properties

AbstractThe radical polymerization of diglycidyl fumarates was performed to give the poly(fumarate)s bearing epoxy groups in the side chains. Their post‐polymerization modification with carbon dioxide afforded the poly(fumarate)s containing the five‐membered cyclic carbonate structures by the reaction of epoxy groups in the polymer side chains with carbon dioxide. Besides, the thermal stability and behavior of the obtained poly(fumarate)s were examined by thermogravimetric and differential scanning calorimetry analyses.

Investigation of pH-dependent extraction methods for PFAS in (fluoropolymer-based) consumer products: A comparative study between targeted and sum parameter analysis

Here, we report a comparative study of different sum parameter analysis methods for the extraction of per- and polyfluoroalkyl substances (PFAS) from manufactured consumer products, which can be measured by combustion ion chromatography (CIC). Therefore, a hydrolysis-based extraction method was further developed, which accounts for the addition of hydrolyzable covalently bound polyfluoroalkylated side-chain polymers (SFPs) to the extractable organic fluorine portion of the mass balance proposed as "hydrolyzable organically bound fluorine" (HOF). To test this hypothesis, the method was applied to 39 different consumer products containing fluoropolymers or monomeric PFAS taken from four different categories: outdoor textiles, paper packaging, carpeting, and permanent baking sheets. We also evaluated the method's efficiency by extracting four synthesized fluorotelomer polyacrylate reference compounds. The total fluorine (TF) and extractable organically bound fluorine (EOF) values were measured through CIC using established protocols. The TF values ranged from sub-ppb to %-levels, depending on the compound class. All samples showed results for hydrolyzed organofluorine (HOF) between 0.03 and 76.3 μg/g, while most EOF values were lower (<LOD to 58.1 μg/g). Moreover, the methods were contrasted with the "total hydrolyzable precursor" (THP) assay analyzed using gas-chromatography coupled mass spectrometry (GC-MS), which yielded concentrations of 6:2–10:2 fluorotelomer alcohols (<LOD-568 μg/g) for textile and paper samples. Furthermore, targeted analytical investigation of 25 compounds via liquid chromatography coupled tandem mass spectrometry (LC-MS/MS) was conducted and accounted for significantly lower sum amounts (<LOD-0.98 μg PFAS/g). To estimate the fluorine mass balance of all methods, the fluorine levels of target analytical data were calculated and compared to the sum parameter values and evaluated. Finally, the efficiency of the extraction method was approximated by the recovery analysis of four selected SFP model compounds compared to their TF values, yielding 36.7–74.0% after extraction and 3.8–36.3% after processing the extract for the HOF sum parameter.

Engineering of bioorthogonal polyzymes through polymer sidechain design.

Synthetic polymer scaffolds can encapsulate transition metal catalysts (TMCs) to provide bioorthogonal nanocatalysts. These 'polyzymes' catalyze the in situ generation of therapeutic agents without disrupting native biological processes. The design and modification of polymer scaffolds in these polyzymes can enhance the catalytic performance of TMCs in biological environments. In this study, we explore the hydrophobic design space of an oxanorborneneimide-based polymer by varying the length of its carbon side chain to engineer bioorthogonal polyzymes. Activity studies indicate that modulating the hydrophobicity of the polymer scaffold can be used to enhance the catalyst loading efficacy, catalytic activity, and serum stability of polyzymes. These findings provide insight into the structural elements contributing to improving polymeric nanocatalysts for a variety of applications.

Fluorescence color change of supramolecular polymer networks controlled by crown ether-cation recognition.

We report a fluorescent supramolecular polymer networks (SPNs) system based on crown ether-cation recognition. The polymer side chains bear ammonium cations, which can be recognized by host molecules with a B15C5 unit and a quinoline group at each end. The quinoline group makes the host molecule exhibit blue fluorescence. After the formation of SPNs, the recognition of the crown ether-cation transforms the blue fluorescence into yellow fluorescence. The accompanying fluorescence color change during the formation of SPNs makes it with potential applications in the fields of display, printing, information storage, and bioimaging.

Thermal cleavage of hydrogen bond-induced LCST-type phase separation of PHEMA and related poly(hydroxyalkyl (meth)acrylate)s in mixed organic solvents

The length of the alkyl groups in both the polymer side chain and 1-alcohol good solvents would dictate the critical molar ratio for LCST-type phase separation.

Low hysteresis zwitterionic supramolecular polymer ion-conductive elastomers with anti-freezing properties, high stretchability, and self-adhesion for flexible electronic devices.

The fabrication of stretchable ionic conductors with low hysteresis and anti-freezing properties to enhance the durability and reliability of flexible electronics even at low temperatures remains an unmet challenge. Here, we report a facile strategy to fabricate low hysteresis, high stretchability, self-adhesion and anti-freezing zwitterionic supramolecular polymer ion-conductive elastomers (ICEs) by photoinitiated polymerization of aqueous precursor solutions containing a newly designed zwitterionic monomer carboxybetaine ureido acrylate (CBUIA) followed by solvent evaporation. The resultant poly(carboxybetaine ureido acrylate) (PCBUIA) ICEs are highly stretchable and self-adhesive owing to the presence of strong hydrogen bonds between ureido groups and dipole-dipole interactions of zwitterions. The zwitterion groups on the polymer side chains and loaded-lithium chloride endow PCBUIA ICEs with excellent anti-freezing properties, demonstrating mechanical flexibility and ionic transport properties even at a low temperature (-20 °C). Remarkably, the PCBUIA ICEs demonstrate a low hysteresis (≈10%) during cyclic mechanical loading-unloading (≤500%), and are successfully applied as wearable strain sensors and triboelectric nanogenerators (TENGs) for energy harvesting and human motion monitoring. In addition, the PCBUIA ICE-based TENG was used as a wireless sensing terminal for Internet of Things smart devices to enable wireless sensing of finger motion state detection.

Construction of secondary and tertiary chiral structures in side-chain azobenzene polymers with flexible main chains

The effects of chiral stereocenter distance, side chain steric hindrance, and polymer liquid crystallinity on the construction of chiral structure in side-chain azobenzene polymers with flexible main chains are investigated.

Synthesis and property modulation of linearly polarized luminescent side-chain polymers with room-temperature phosphorescence

A series of purely organic linearly polarized room-temperature phosphorescent side-chain polymers were successful synthesized using a template-assisted method.

Mesomorphic and photochromic luminescent behaviour of side-chain liquid crystalline polymers containing di-substituted cyanostilbene groups with the different number of alkyl tail chain

Mesomorphic and photochromic luminescent behaviour of side-chain liquid crystalline polymers containing di-substituted cyanostilbene groups with the different number of alkyl tail chain

Enhancing charge transport in isoindigo-based donor–acceptor copolymers by combining ionic doping with polar alkoxy side chains

Side chains of polymers play a crucial role in manipulating polymer interchain interactions, especially polar side chains that promote strong molecular stacking and facilitate ionic diffusion.