Hydrophobic Acrylate Research Articles

Functional Nanocarriers for Drug Delivery by Surface Engineering of Polymeric Nanoparticle Post-Polymerization-Induced Self-Assembly

Engineered polymeric nanoparticles (NPs) have been comprehensively explored as potential platforms for diagnosis and targeted therapy for several diseases including cancer. Herein, we designed functional poly(acrylic acid)-b-poly(butyl acrylate) (PAA-b-PBA) NPs using reversible addition-fragmentation chain-transfer (RAFT)-mediated emulsion polymerization via polymerization-induced self-assembly (PISA). The hydrophilic PAA-macroRAFT, forming a stabilizing shell (i.e., corona), was chain-extended using the hydrophobic monomer n-butyl acrylate (n-BA), resulting in stable, monodisperse, and reproducible PAA-b-PBA NPs, typically having a diameter of 130 nm. The surface engineering of the PAA-b-PBA NP post-PISA were explored using a two-step approach. The hydrophilic NP-shell corona was modified with allyl groups under mild conditions, using allylamine in water, which resulted in stable allyl-functional NPs (allyl-NPs) suitable for further bioconjugation. The allyl-NPs were subsequently conjugated with a thiol-functional fluorescent dye (BODIPY-SH) to the allyl groups using “thiol-ene”-click chemistry, to mimic the attachment of a thiol-functional target ligand. The successful attachment of BODIPY-SH to the allyl-NPs was corroborated by UV–vis spectroscopy, showing the characteristic absorbance of the BODIPY-fluorophore at 500 nm. Despite modification of NPs with allyl groups and attachment of BODIPY-SH, the NPs retained their colloidal stability and monodispersity as indicated by DLS. This demonstrates that post-PISA functionalization is a robust method for synthesizing functional NPs. Neither the NPs nor allyl-NPs showed significant cytotoxicity toward RAW264.7 or MCF-7 cell lines, which indicates their desirable safety profile. The cellular uptake of the NPs using J774A cells in vitro was found to be time and concentration dependent. The anti-cancer drug doxorubicin was efficiently (90%) encapsulated into the PAA-b-PBA NPs during NP formation. After a small initial burst release during the first 2 h, a controlled release pattern over 7 days was observed. The present investigation demonstrates a potential method for functionalizing polymeric NP post-PISA to produce carriers designed for targeted drug delivery.

A tough and self-fusing elastomer tape

A multifunctional polymer self-fusing elastomer tape strengthened by the topological entanglement and H-bonds demonstrates an antibacterial activity, and appealing ability to seal liquid leakage (water, oil) and stop bleeding. • H-bonding and topological entanglements contribute to a self-fusing elastomer. • The tape seals the liquid leakage and bleeding, independent of surface nature. • This self-fusing tape kills harmful bacteria by intrinsic weak acidity. Pressure-sensitive and adhesive tapes have been widely used for many purposes. However, their intrinsically strong sticky nature and weak strength severely limits their applications to vulnerable surfaces and harsh conditions. Herein, a multifunctional tough and self-fusing elastomer tape is fabricated for the first time by simple copolymerization of a model hydrophobic monomer 2-methoxyethyl acrylate (MEA) and a model weak acid-containing monomer acrylic acid (AAc). The PMEA-PAAc copolymer elastomers demonstrate high strengths and toughness with a maximum Young’s modulus, tensile stress, breaking strain, toughness, and recovery stress up to 74.19 MPa, 10.77 MPa, 2260%, 48.95 MJ/m 3 , and 0.60 MPa, respectively, due to hydrogen bonds and hydrophobic interactions. Furthermore, these reversible physical interactions contribute to the room temperature self-fusing ability of the elastomer. Studies on rheological behavior, dynamic mechanical properties and time–temperature equivalence reveal that topological entanglement and hydrogen bonds collectively contribute to the toughness and self-fusing capability. Intriguingly, the weak acidity of PAAc imparts antibacterial activity to the elastomer. Importantly, this elastomer can seal liquid (water and oil) leakage and stop bleeding, which is independent of the adherend surface properties, outperforming the conventional surface-dependent pressure sensitive adhesive and adhesive tape, due to elastic retraction force and self-fusing capability.

Improving Moisture/Thermal Stability and Efficiency of CH3NH3PbI3‐Based Perovskite Solar Cells via Gentle Butyl Acrylate Additive Strategy

Organic–inorganic halide perovskite solar cells (PSCs) are a new class of photovoltaic devices, which have attracted increasing interests due to high efficiency, low cost, and simple fabrication process. Although a remarkable enhancement in power conversion efficiency (PCE) has been achieved in the last decade, the stability issue, including high water/heat sensitivity and UV light‐induced degradation, has become one of the main obstacles for practical applications of PSCs. Herein, hydrophobic butyl acrylate with CO and CC groups is reported as a new additive to enhance the PCE and moisture/thermal stability of CH3NH3PbI3‐based PSCs, which improves the quality of the perovskite film by promoting defect passivation, constructing a suitable energy‐level alignment, and increasing the charge carrier lifetime in PSCs. Such an additive is easily introduced into PSCs without the need for thermal treatment, which is typically required by other additives, causing a negative effect on the efficiency. The CH3NH3PbI3‐based PSC with butyl acrylate additive shows a superior PCE of 20.0%, 19% higher than that of the unmodified device (16.8%), as well as much improved moisture/thermal stability. Herein, a facile way is provided to enhance the PCE and stability of CH3NH3PbI3‐based PSCs simultaneously, which facilitates the commercialization of PSCs.

Process development of water-based polyurethane with acrylate terminal group under water vapor permeability and water repellency for nylon fabric

This study synthesized water-based polyurethane with acrylate terminal group (WPUA) using the long carbon chain of stearyl acrylate to synthesize hydrophobic poly-stearyl acrylate (PSA). The proposed process could minimize environmental pollution caused by fluorine-containing monomers. As a water-based polyurethane (WPU) end-capping agent, the hydrophobic PSA and the hydrophilic and water vapor permeable WPU are copolymerized to form a WPUA functional resin with simultaneous water vapor permeability (WVP) and water repellency. Here, 2-mercaptoethanol was used to control the molecular weight of PSA to prepare the acrylate end-capping agent. PSA was then employed in WPU to form WPUA, which is characterized by the moisture permeability of WPU and water repellency of acrylic resin simultaneously. During the WPUA process, dimethylacetamide was used as a neutralizer to replace the traditional toxic chemical control drug triethylamine. This study set up the material and chemical structure to replace the toxic chemical-controlled drugs and organofluoride in the traditional preparation of moisture permeable and water repellent materials. The proposed process was proven to reduce the consumption of organic solvent, achieve WPUA copolymer stability, and provided moisture permeable and water repellent functions. In addition, Fourier transform infrared spectroscopy was used to determine the structure of WPUA, while thermogravimetry analysis and differential scanning calorimetry were performed to establish the thermal properties of WPUA. After the WPUA was padded on nylon fabric, its water drop contact angle was observed through a scanning electron microscope. The results showed that the contact angle of nylon fabric increased significantly, water repellency was reached, and WVP rises by 23.75%.

Amphiphilic Dicyclopentenyl/Carboxybetaine-Containing Copolymers for Marine Fouling-Release Applications.

Zwitterionic materials received great attention in recent studies due to their high antifouling potential, though their application in practical coatings is still challenging. Amphiphilic polymers have been proven to be an effective method to combat fouling in the marine environment. This study reports the incorporation of small amounts of zwitterionic carboxybetaine methacrylate (CBMA) into hydrophobic ethylene glycol dicyclopentenyl ether acrylate (DCPEA). A new set of copolymers with varying amphiphilicities was synthesized and coated on chemically modified glass substrates. The antifouling capabilities were assessed against the diatom Navicula perminuta and multiple species in the field. Unsurprisingly, high diatom densities were observed on the hydrophobic control coatings. The integration of small zwitterionic contents of only ∼5 wt % was already sufficient to rapidly form a hydrophilic interface that led to a strong reduction of fouling. Ultralow fouling was also observed for the pure zwitterionic coatings in laboratory experiments, but it failed when tested in the real ocean environment. We noticed that the ability to absorb large amounts of water and the diffuse nature of the interphase correlate with the adsorption of silt, which can mask the hydrophilic chemistries and facilitate the settlement of organisms. The amphiphilic coatings showed low fouling in dynamic short-term field exposures, which could be explained by the reduced tendency of the coatings for sediment adsorption.

2D Titanium Carbide (Ti3C2Tx) in Accommodating Intraocular Lens Design

AbstractWhile intraocular lenses (IOL) are used to restore visual acuity in cataract patients, they are limited in their development as no clinically available lens can effectively mimic the accommodative function of the eye's natural lens. The optoelectronic properties of 2D transition metal carbides and/or nitrides (MXenes), including high electronic conductivity, optical transparency, flexibility, biocompatibility, and hydrophilicity, suggest potential use within an accommodating IOL. This study investigates the use of Ti3C2Tx (MXene) as a transparent, conductive electrode to allow changes in optical power. Ti3C2Tx is synthesized and spin‐coated on hydrophobic acrylate IOLs, achieving a sheet resistance ranging from 0.2–1.0 kΩ sq−1 with 50–80% transmittance in the visible region. Human lens epithelial and monocytic cells show no cytotoxic nor inflammatory response to the coated lenses. An adjustable focus test cell is fabricated using a liquid crystal (LC) layer sandwiched between Ti3C2Tx coatings on a solid support. Molecular reorientation of the LC layer, through an applied electric field, results in changes in optical power as objects viewed through the test cell appeared in and out of focus. This study is the first step toward the use of Ti3C2Tx within an accommodative IOL design through demonstration of reversible, controlled, adjustable focus.

Glistening formation in a new hydrophobic acrylic intraocular lens

BackgroundThe formation of fluid-filled microvacuoles, termed glistenings, is a common complication of intraocular lenses (IOLs) made from hydrophobic acrylate. Using our well-established in-vitro laboratory method, we evaluated a new IOL material’s resistance to glistening formation.MethodsAn in-vitro stress test for glistening induction was performed on 20 samples of hydrophobic acrylic IOLs: ten of the new Eyecryl ASHFY600 (Biotech Vision Care, Ahmedabad, India) compared with ten samples of AcrySof IQ SN60WF (Alcon, Fort Worth, USA). The number of microvacuoles per square millimetre (MV/mm2) was evaluated in five sections of each IOL. The results for each model were compared and rated on a modified Miyata Scale for grading glistening severity.ResultsIn all cases, glistening number was higher in the central section of the IOL optic than in the periphery. Mean number of MV/mm2 was highest in the central part of the AcrySof IQ SN60WF, with 41.84 (±27.67) MVs/mm2. The lowest number of glistenings was found in the five sections of the Eyecryl ASHFY600 with 0.52 (±0.24) MVs/mm2. Mean value of the Eyecryl ASHFY600 IOL, using the Miyata Scale, was Zero.ConclusionIn this in-vitro laboratory study, the new hydrophobic acrylic IOL showed a high resistance to microvacuole formation. Results from this in-vitro study suggest that glistening numbers will be low in clinical use in the Eyecryl ASHFY600.

Temperature and pH-Dependent Response of Poly(Acrylic Acid) and Poly(Acrylic Acid-co-Methyl Acrylate) in Highly Concentrated Potassium Chloride Aqueous Solutions.

In this study, the phase transition phenomena of linear poly(acrylic acid) (PAA) and linear or star-shaped poly(acrylic acid-co-methyl acrylate) (P(AA-co-MA)) in highly concentrated KCl solutions were investigated. The effects of polymer molecular weight, topology, and composition on their phase transition behavior in solution were investigated. The cloud point temperature (TCP) of polymers drastically increased as the KCl concentration (CKCl) and solution pH increased. CKCl strongly influenced the temperature range at which the phase transition of PAA occurred: CKCl of 1.0–2.2 M allowed the phase transition to occur between 30 and 75 °C. Unfortunately, at CKCl above 2.6 M, the TCP of PAA was too high to theoretically trigger the crystallization of KCl. The addition of hydrophobic methyl acrylate moieties decreased the TCP into a temperature region where KCl crystallization could occur. Additionally, the hydrodynamic diameters (Dh) and zeta potentials of commercial PAA samples were examined at room temperature and at their TCP using dynamic light scattering. The salt concentration (from 1 to 3 M) did not impact the hydrodynamic diameter of the molecules. Dh values were 1500 and 15 nm at room temperature and at TCP, respectively.

Amino-functionalized polymethylmethacrylate-co-polyethyleneimine (PMMA-co-PEI) as a template to fabricate nano-silica

Polymer template method is a general and facile to fabricate nano-structural matters. Some amphiphilic polymers or co-polymers were used as templates to synthesize nano-silica. In this contribution, polymethacrylate (PMMA) employed was a commercial hydrophobic acrylate polymer and grafted with a strong hydrophilic polyethyleneimine (PEI, a densely amino-groups polymer) via aminolysis reaction, which was monitored and identified by means of FT-IR. The aminolysis reaction was optimized and the suitable reaction time was 12 h at 110 °C. The obtained copolymer, PMMA-co-PEI was applied as a template to prepare nano-silica spheres that was characterized by a scanning electron microscope (SEM). When the dosage was 1 wt% of purified PMMA-co-PEI, the resultant nano-silica had uniform particle size, and average diameter of 311 nm. When the dosage of PMMA-co-PEI was increased to 2 wt% or 4 wt%, the resultant particles became bigger and inclined to aggregate. Nano-silica afforded by this template method will be a promising material in application of catalysis, energy, biology and chromatographic analysis and the copolymer of PMMA-co-PEI will be a template for producing metal oxide nano-spheres.

Highly stretchable and thermally healable polyampholyte hydrogels via hydrophobic modification

Aqueous solutions or gels of polyampholytes attract interest for more than half a century due to their several attractive properties. We present here thermally healable hydrophobically modified physical polyampholyte (PA) hydrogels based on oppositely charged 2-acrylamido-2-methylpropane-1-sulfonic acid sodium salt (AMPS) and (3-acrylamidopropyl) trimethylammonium chloride (APTAC) monomers. PA hydrogels were prepared via micellar polymerization technique in the presence of the hydrophobic monomer n-octadecyl acrylate (C18A) in aqueous sodium dodecyl sulfate (SDS) solutions. Charge-balanced PA hydrogels containing 60–90% water exhibit a high tensile strength and stretchability of up to 202 kPa and 1239%, respectively. Above 7 mol% C18A, swollen hydrogels containing around 90% water exhibit much better mechanical properties as compared with the corresponding as-prepared ones because of the stronger hydrophobic interactions in the absence of SDS micelles. Cut-and-heal tests conducted at 50 °C reveal a complete healing efficiency with respect to Young’s modulus for all as-prepared PA hydrogels within 1–4 h.

Morphological changes in rabbit cornea after implantation of a new keratoprosthesis supporting plate

To evaluate biocompatibility of the new keratoprosthesis supporting plates (KSP) in rabbits in vivo. The study included 15 chinchilla rabbits. In the first group (5 rabbit eyes) KSP made of hydrophobic acryl with square penetrating holes of 220×220 micron (model 1) were inserted into rabbits' corneas. In the second group (5 eyes), KSP made of hydrophobic acryl were used that had trapezoidal fenestrations with size (from 170×130 micron to 180×70 microns) gradually changing from periphery to the center of KSP (model 2). The control group rabbits (5 eyes) had 1/2 of Fyodorov-Zuev KSP made of titanium implanted. All animals were observed for up to 3 months with biomicroscopy and optical coherence tomography of the anterior segment. The animals were then euthanized and had their corneo-scleral discs excised and then examined with optical microscopy and scanning electron microscopy (SEM). After 3 months, there was only one case of KSP protrusion in the first group. In the second group, thinning of the corneal layers above the central part of KSP occurred in one case. The presence of polymer KSP (of both models) in the corneal stroma was found not to cause formation of rough fibrotic tissue. At the same time, adhered cellular and fibrous elements were discovered on the surface and inside the holes of the polymer KSP, while on the surface of the titanium plate cellular elements were absent. Supporting plates made of hydrophobic acrylic material can potentially serve as a foundation for the new keratoprosthesis design.

Systematic Study on the Biomechanical Stability of C-Loop Intraocular Lenses: Approach to an Optimal Design of the Haptics.

To study the main design parameters that affect the mechanical stability of C-loop intraocular lenses, leading to an optimal design that minimizes the axial displacement, tilt and rotation. A total of 144 geometrical variations were studied on a 1-piece, non-angulated, C-loop hydrophobic acrylate intraocular lens. The study was performed in a finite element modeling simulation. The suitable set of variations was determined using a mixed-factorial analysis, allowing to analyse the impact of the different designs on the mechanical stability of the lens (compression force, axial displacement, tilt and rotation). The design parameters under study were: the length, width, thickness and opening angle of the haptic, the haptic-optic junction and the start of the haptic curvature. The compression (or reaction) force is affected by the haptic width, the haptic-optic junction, and the interaction between both. The axial displacement is mainly affected by the width and thickness of the haptic, and the size of the haptic-optic junction as well. The tilt is affected by the haptic thickness and the interaction between the haptic curvature and the haptic-optic junction. The rotation is affected by the start of the haptic curvature, the haptic-optic junction and the haptic width. The haptic-optic juntion is one of the most influential parameters affecting the four responses studied of the C-Loop IOL. The smaller the haptic-optic juntion, the better biomechanical stability.

Dual physically and chemically cross-linked polyelectrolyte nanohydrogels: Compositional and pH-dependent behavior studies

This study describes the composition-property relationship of a dual chemically and physically cross-linked nanohydrogel (NHG) containing a high concentration of hydrophilic pH-sensitive acrylic acid (AA). The physical and chemical cross-linking were incorporated using the aggregation of hydrophobic butyl acrylate (BA) and covalent bond of a bifunctional monomer (ethylene glycol dimethacrylate), respectively. Implementing a direct one-pot semi-batch emulsion polymerization technique in an acidic condition yielded monodispersed (PDI < 0.2) NHGs with a collapsed hydrodynamic radius of 60–100 nm. Titration studies revealed the significant effect of the chemical and physical cross-linking on the amounts of accessible carboxyl groups and their ionization behavior. These NHG dispersions displayed good colloidal stability over a wide pH and duration, the Donnan equilibrium is responsible for the observed swelling behavior of these NHGs.

Influence of vanillin acrylate and 4-acetylphenyl acrylate hydrophobic functional monomers on phase separation of N-isopropylacrylamide environmental terpolymer: fabrication and characterization

In the present study, we synthesized new functional hydrophobic acrylate monomers. The first monomer was based on 4-acetylacetophenone, and the other one was based on vanillin as a renewable resource. The starting material was reacted with acryloyl chloride for the formation of 4-acetylphenyl acrylate (APA) and 4-formyl-2-methoxyphenylacrylate (vanillin acrylate) or (VA), respectively. The chemical structures were deduced by 1H NMR, 13C NMR, and FTIR. The effect of these monomers on the transition temperature or lower critical solution temperature of thermo-responsive N-isopropylacrylamide was achieved by the free radical polymerization of three different molar concentrations of both APA and VA with NIPAAm in solution and using 2,2′azobis(isobutyronitrile) (AIBN) as an initiator. The terpolymers were chemically evaluated. They have been also investigated by gel permission chromatography (GPC) for molecular weight and molecular weight distribution; the glass temperatures were determined by differential scanning calorimetry DSC; X-ray diffraction (XRD) was used for the extent of crystallinity; scanning electron microscopy was used (SEM) for surface morphology. The phase separation and lower critical solution temperature Tc were measured using two methods: UV–Vis spectroscopy for turbidity measurements and micro-DSC of the polymer solution. In the future, we will use these polymers in the bio-separation process and the formation of a responsive hydrogel.

Blue- and green-emitting hydrophobic carbon dots: preparation, optical transition, and carbon dot-loading

In the past decade, hydrophobic fluorescent carbon dots (OCDs) have received little attention, and its potential application and light transition mechanism is seldom explored. Here we report a novel one-step approach for synthesizing blue- and green-emitting hydrophobic fluorescent carbon dots (OCDb and OCDg) by calcinating with the uses of citric acid and hexadecylamine as initial reactants. The optimal conditions for preparing OCDb and OCDg were obtained by using the Taguchi L25 (35) orthogonal array. The highest quantum yield and product yield of OCDs reached 80.2% and 57.1%, respectively, larger than those from most of all the known reports. The fluorescent stability of OCDb and OCDg was excellent under UV irradiation (30 W) for days. The luminescent color of OCDs showed a great dependence on reaction conditions. It is easier to get OCDg via a reaction kept at a high temperature for a long time. The optical transition mechanism was studied for the two kinds of color OCDs, and therefore proposed in combination with their optical properties and surface groups. The reason for light transition is probably related to an appropriate critical ratio and surface density of the C=O and N–H bond in the surface structure of the product. For the OCDg, the concentration matching ratio of N–H and C=O bonds in the surface structure of the green-emitting product is approximately between d/2 and 3d/2, where d is a fixed constant. Lower than or higher than this critical ratio range, the product emits blue light. Based on their high fluorescence quantum efficiency and the advantages mentioned above, these OCDs were then respectively used for preparing hydrophobic fluorescent carbon dot-loading liposomes and acrylate films, both exhibiting a perfect performance with no fluorescence quenching.

Self-Healing Alkyl Acrylate-Based Supramolecular Elastomers Cross-Linked via Host–Guest Interactions

We prepared acrylamide monomers with permethylated cyclodextrins (PM-CDAAmMe) or peracetylated cyclodextrins (PAc-CDAAmMe). PM-CDAAmMe and PAc-CDAAmMe are soluble in various hydrophobic liquid acrylate monomers, and they can form inclusion complexes with guest monomers such as adamantane or fluoroalkyl groups tethered to a vinyl residue. The bulk polymerization of the liquid acrylate monomers with the PM-CDAAmMe or PAc-CDAAmMe monomers and the guest monomers gave highly flexible and tough elastomers. Tensile tests on the obtained supramolecular elastomers showed fracture strains of over 800% and fracture energies that were 12 times larger than those of covalently cross-linked conventional elastomers, indicating that the host–guest cross-linking made the supramolecular elastomers quite tough. During the deformation process, the applied stress is dispersed into the supramolecular elastomers by dissociation and recombination of the reversible host–guest complex. Moreover, these host–guest complexes also allo...

Single-chain self-folding in an amphiphilic copolymer: An integrated experimental and computational study

An amphiphilic random copolymer of hydrophilic poly(ethylene glycol) methyl ether methacrylate with hydrophobic perfluorohexylethyl acrylate, PEGMA77-co-FA23, was synthesized by ATRP and used to investigate self-assembling into nanostructures in water and chloroform solutions, both experimentally and computationally. The dynamic light scattering measurements on water solutions of the copolymer at room temperature evidenced the presence of nanoassemblies with hydrodynamic diameter Dh = 4 ± 1 nm. The behavior of fluorescence emission intensity of water solutions with added ethidium bromide suggested confinement of the molecular rotor within a hydrophobic environment of the copolymer. Moreover, these nanoassemblies were thermoresponsive and reversibly collapsed into much larger, multi-chain aggregates with Dh = 390 ± 20 nm at a critical temperature of 55 °C (5 mg mL−1). Molecular dynamics simulations revealed the formation of single-chain, prolate globular nanoassemblies with a structural variability in water solution at room temperature. The evolutions of the simulated radius of gyration (Rg), asphericity, prolateness and solvent-accessible surface area were analyzed along the folding trajectories. Thus, self-folding appeared to result from the interplay between hydrophobic interactions and structural constraints which leads to rather complex nanostructures (Rg = 20–25 Å, 200 ns simulation). By contrast, folding in much more open polymer conformations (Rg = 30–40 Å) was predicted for chloroform solutions.

Crosslinked Organosilicon-Acrylate Copolymer Moisture Barrier Thin Film Fabricated by Initiated Chemical Vapor Deposition (iCVD)

Crosslinked organosilicon-acrylate copolymer thin film with desired chemical composition was successfully fabricated by a simply modified initiated chemical vapor deposition (iCVD) process. Unlike the conventional iCVD copolymerization process, in our novel process, comonomers were injected together as one gas phase into the polymerization chamber from miscible liquid comonomer mixture. 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane (V4D4) and cyclohexyl methacrylate (CHMA) were used as the comonomers and tert-butyl peroxide was used as the initiator. From Fourier transform infrared (FTIR) spectra and solvent resistance test, we clearly confirmed that the crosslinked copolymer thin film with desired chemical composition could be obtained by controlling only the mixing ratio of liquid comonomers. It is expected that crosslinkable V4D4 organosilicon moiety provides hydrophobic moisture barrier property and CHMA acrylate moiety provides mechanical flexibility and better adhesion. We observed a certain level of moisture blocking capability of the copolymer thin film, implying potential application of the crosslinked organosilicon-acrylate copolymer thin film as flexible polymer buffer layer in organic/inorganic or metal oxide hybrid moisture barrier for flexible display or electronic devices.

Mechanically tough and recoverable hydrogels via dual physical crosslinkings

ABSTRACTDevelopment of functional tough hydrogels with new network structures and energy dissipation mechanisms has great promise for many applications. Here, a new type of physical hydrogel crosslinked by hydrophobic association and hydrogen bonds was synthesized by a facile micellar copolymerization of hydrophobic methyl acrylate (MA) monomers and hydrophilic N‐hydroxyethyl acrylamide (HEAA) monomers in the presence of Tween80 micelles. Strong hydrophobic association between inner MA and Tween80 and hydrogen bonds between external polyHEAA and Tween80 provide two distinct crosslinkers to construct mechanically tough and recoverable network. Mechanical properties of polyHEAA‐MA@Tween80 hydrogels strongly depended on network components (HEAA, MA; Tween80 concentrations). At optimal conditions, the hydrogels can achieve fracture stress of 700 kPa, fracture strain of 1687 mm/mm, elastic modulus of 195 kPa, and tearing energy of 1598 J/m2. Due to the reversible nature of physical interactions, polyHEAA‐MA@Tween80 hydrogels can achieve fast stiffness/toughness recovery of 60%/33% without any external stimuli and resting time at room temperature. This work demonstrates a new design strategy to fabricate a new a single‐network hydrogel with high mechanical and self‐recovery properties by incorporating both hydrophobic association and hydrogen bonds in the network, which may provide alternative viewpoint for the design of multifunctional tough hydrogels. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2018, 56, 1294–1305

Precisely Tunable Sol-Gel Transition Temperature by Blending Thermoresponsive ABC Triblock Terpolymers.

Here, we report a facile methodology to control the sol-gel transition temperature (Tgel) of a physically cross-linked hydrogel by blending two kinds of ABC triblock terpolymers. Well-defined triblock terpolymers including thermosensitive N-isopropylacrylamide (NIPAAm), ABC1, and ABC2, were prepared by sequential reversible addition-fragmentation chain transfer polymerization. The chemical structure as well as the molecular weight of the A and B blocks for both polymers are identical, whereas the C blocks are different. The C block of ABC1 (C1) is a statistical copolymer of NIPAAm with hydrophobic n-butyl acrylate (BA), while that of ABC2 (C2) is a PNIPAAm homopolymer. Independently prepared ABC triblock terpolymer solutions exhibit well-defined sol-gel transitions. The Tgel of ABC1 is lower than that of ABC2 since hydrophobic BA is copolymerized into block C1. Remarkably, the Tgel varies linearly within this temperature range by simply blending the two polymers, while the resultant gel strength (∼G') remains almost unchanged. Therefore, the Tgel can be precisely adjusted by the mixing ratio of the two polymers. This method for straightforward manipulation of Tgel has great potential for various soft material applications such as biomaterials for tissue engineering, drug delivery systems, and injectable gels.