Polymer Colloids Research Articles

Morphological Evolution of Hybrid Block Copolymer Particles: Toward Magnetic Responsive Particles.

The co-assembly of block copolymers (BCPs) and inorganic nanoparticles (NPs) under emulsion confinement allows facile access to hybrid polymeric colloids with controlled hierarchical structures. Here, the effect of inorganic NPs on the structure of the hybrid BCP particles and the local distribution of NPs are studied, with a particular focus on comparing Au and Fe3O4 NPs. To focus on the effect of the NP core, Au and Fe3O4 NPs stabilized with oleyl ligands were synthesized, having a comparable diameter and grafting density. The confined co-assembly of symmetric polystyrene-b-poly(1,4-butadiene) (PS-b-PB) BCPs and NPs in evaporative emulsions resulted in particles with various morphologies including striped ellipsoids, onion-like particles, and their intermediates. The major difference in PS-b-PB/Au and PS-b-PB/Fe3O4 particles was found in the distribution of NPs inside the particles that affected the overall particle morphology. Au NPs were selectively localized inside PB domains with random distributions regardless of the particle morphology. Above the critical volume fraction, however, Au NPs induced the morphological transition of onion-like particles into ellipsoids by acting as an NP surfactant. For PS-b-PB/Fe3O4 ellipsoids, Fe3O4 NPs clustered and segregated to the particle/surrounding interface of the ellipsoids even at a low volume fraction, while Fe3O4 NPs were selectively localized in the middle of PB domains in a string-like pattern for PS-b-PB/Fe3O4 onion-like particles.

Design and evaluation of oral formulation for apixaban

Non-valvular atrial fibrillation (NVAF) is a common form of cardiac arrhythmia that affects 1–1.5% of adults and roughly 10% of elderly adults with dysphagia. Apixaban is an anticoagulant referred to as a factor Xa inhibitor, which has been shown to reduce the risk of stroke and systemic embolism in cases of NVAF. Our objective in the current study was to formulate an orally disintegrating film to facilitate the administration of apixaban to elderly patients who have difficulty swallowing. Researchers have used a wide variety of cellulose-based or non-cellulose-based polymers in a variety of combinations to achieve specific characteristics related to film formation, disintegration performance, drug content, in vitro drug release, and stability. One of the two formulations in this study was specify that bioequivalence criteria met with respect to Cmax of the reference drug (ELIQUIS®) in terms of pharmacokinetic profile. Further research will be required to assess the applicability of orodispersible films created using colloidal polymers of high and low molecular weights to other drugs with poor solubility in water.

Colloidal Polymer-Templated Formation of Inorganic Nanocrystals and their Emerging Applications.

Inorganic nanocrystals possess unique physicochemical properties compared to their bulk counterparts. Stabilizing agents are commonly used for the preparation of inorganic nanocrystals with controllable properties. Particularly, colloidal polymers have emerged as general and robust templates for in situ formation and confinement of inorganic nanocrystals. In addition to templating and stabilizing inorganic nanocrystals, colloidal polymers can tailor their physicochemical properties such as size, shape, structure, composition, surface chemistry, and so on. By incorporating functional groups into colloidal polymers, desired functions can be integrated with inorganic nanocrystals, advancing their potential applications. Here, recent advances in the colloidal polymer-templated formation of inorganic nanocrystals are reviewed. Seven types of colloidal polymers, including dendrimer, polymer micelle, stare-like block polymer, bottlebrush polymer, spherical polyelectrolyte brush, microgel, and single-chain nanoparticle, have been extensively applied for the synthesis of inorganic nanocrystals. Different strategies for the development of these colloidal polymer-templated inorganic nanocrystals are summarized. Then, their emerging applications in the fields of catalysis, biomedicine, solar cells, sensing, light-emitting diodes, and lithium-ion batteries are highlighted. Last, the remaining issues and future directions are discussed. This review will stimulate the development and application of colloidal polymer-templated inorganic nanocrystals.

Fine-tuning of colloidal polymer crystals by molecular simulation.

Through extensive molecular simulations we determine a phase diagram of attractive, fully flexible polymer chains in two and three dimensions. A rich collection of distinct crystal morphologies appear, which can be finely tuned through the range of attraction. In three dimensions these include the face-centered cubic, hexagonal close packed, simple hexagonal, and body-centered cubic crystals and the Frank-Kasper phase. In two dimensions the dominant structures are the triangular and square crystals. A simple geometric model is proposed, based on the concept of cumulative neighbors of ideal crystals, which can accurately predict most of the observed structures and the corresponding transitions. The attraction range can thus be considered as an adjustable parameter for the design of colloidal polymer crystals with tailored morphologies.

Linear growth of colloidal dumbbells into three-lobed polymer nanoparticles mediated by a gradient in surface wettability

Anisotropy is a deciding factor in determining the hydrodynamics and self-assembly of colloidal particles. Linking particle morphology to said behaviors promoted the development of strategies to obtain anisotropic particles exhibiting defined shapes and symmetries. Dumbbell-shaped polymer particles made by phase separation during seeded polymerization are prominent examples. Phase separation among monomer and seed particle yields a liquid protrusion of monomer on the seed. This protrusion is then polymerized, becoming solid and yielding a solid spherical lobe. When this process is performed with spherical seeds, two-lobed particles, known as colloidal dumbbells, are obtained. Repeating this process of lobe formation one or more times could pave the way to tailored particle morphologies. Given the higher degree of anisotropy, multi-lobed particles can expand the rich phase behavior already found for dumbbells. We propose a new route in making anisotropic polymer particles by directing phase separation in a linear direction, thus permitting linear growth. Colloidal particles composed of three individual polymer lobes with the potential for site-specific modifications are obtained. Triggering of the phase separation is done complementary to prior efforts in fabricating three-lobed polymer particles based on cross-linked precursor particles. We will show that tailored surface properties of anisotropic seed particles can prove as an effective tool not only to promote the monomer-polymer phase separation, but also to guide it in a linear direction. Such gradients in surface functionalization open perspectives for making polymer colloids on a large scale in whose custom-tailored shapes their phase behavior and superstructure formation are already established.Graphical

Monolithic light concentration by core–shell TiO2 nanostructures templated by monodisperse polymer colloidal monolayers

Nanostructured dielectric overlayers can be used to increase light absorption in nanometer-thin films used for various optoelectronic applications. Here, the self-assembly of a close-packed monolayer of polystyrene nanospheres is used to template a core–shell polystyrene-TiO2 light-concentrating monolithic structure. This is enabled by the growth of TiO2 at temperatures below the polystyrene glass-transition temperature via atomic layer deposition. The result is a monolithic, tailorable nanostructured overlayer fabricated by simple chemical methods. The design of this monolith can be tailored to generate significant absorption increases in thin film light absorbers. Finite-difference, time domain simulations are used to explore the design polystyrene-TiO2 core–shell monoliths that maximize light absorption in a 40 nm GaAs-on-Si substrate as a model for a photoconductive antenna THz emitter. An optimized core–shell monolith structure generated a greater than 60-fold increase of light absorption at a single wavelength in the GaAs layer of the simulated model device.

Step-growth polymerization of supracolloidal chains from patchy micelles of diblock copolymers

HypothesisThe formation of supracolloidal chains from the patchy micelles of diblock copolymers bears a close resemblance to traditional step-growth polymerization of difunctional monomers in many aspects, including chain-length evolution, size distribution, and initial-concentration dependence. Thus, understanding the colloidal polymerization based on the step-growth mechanism can offer potential control over the formation of supracolloidal chains in terms of chain structure and reaction rate. ExperimentsWe analyzed the size evolution of supracolloidal chains of patchy micelles of PS-b-P4VP by investigating a large number of colloidal chains visualized in SEM images. We varied the initial concentration of patchy micelles to achieve a high degree of polymerization and a cyclic chain. To manipulate the polymerization rate, we also changed the ratio of water to DMF and adjusted the patch size by employing PS(25)-b-P4VP(7) and PS(145)-b-P4VP(40). FindingsWe confirmed the step-growth mechanism for the formation supracolloidal chains from patchy micelles of PS-b-P4VP. Based on this mechanism, we were able to achieve a high degree of polymerization early in the reaction by increasing the initial concentration and form cyclic chains by diluting the solution. We also accelerated colloidal polymerization by increasing the ratio of water to DMF in the solution and patch size by using PS-b-P4VP with a larger molecular weight.

Plant-based meat analogs and fat substitutes, structuring technology and protein digestion: A review

There is currently an increasing trend in the consumption of meat analogs and fat substitutes due to the health hazards by excessive consumption of meat. Simulating the texture and mouthfeel of meat through structured plant-derived polymers has become a popular processing method. In this review, the mechanical structuring technology of plant polymers for completely replacing real meat is mainly introduced in this review, which mainly focuses on the parameters and principles of mechanical equipment for the production of vegan meat. The difference in composition between plant meat and real meat is mainly reflected in the protein, and particular attention should be paid to the digestive characteristics of plant meat protein in the gastrointestinal tract. Therefore, the differences in the protein digestibility properties of meat analogs and real meat is discussed in this review, focusing primarily on protein digestibility and peptide/amino acid composition of mechanically structured vegan meats. In terms of fat substitutes for meat products, the types of plant polymer colloidal systems used for meat fat substitutes is comprehensively introduced, including emulsion, hydrogel and oleogel.

Preparation of sustained-release tablets using a solventless-mixing tablet coating technique: Particle design of dry ammonioalkyl methacrylate copolymer latex with high coating performance using sodium lauryl sulfate

The aim of this study was to produce sustained-release tablets by V-shaped blending of polymer and tablets without using solvents or heating, and we investigated the design of polymer particles with high coating performance by modifying the structure of the particles using sodium lauryl sulfate. Dry-latex particles of ammonioalkyl methacrylate copolymer were prepared by adding the surfactant into aqueous latex, followed by freeze drying. The resulting dry latex was mixed with tablets (1:10) using a blender and the resulting coated tablets were characterized. Tablet coating by the dry latex was promoted as the weight ratio of surfactant to polymer increased. At a surfactant ratio of 5%, deposition of the dry latex was most effective and the resulting coated tablets (annealed at 60 °C/75%RH for 6 h) exhibited sustained-release characteristics over a period of 2 h. The addition of SLS prevented coagulation of colloidal polymer in the freeze drying, resulting in a loose-structured dry latex. This latex was easily pulverized by V-shaped blending with tablets and the resulting fine particles with high adhesiveness were deposited on the tablets. However, at a surfactant ratio of 10%, the coating of dry latex decreased due to reduced adhesiveness.

A Paper-Based Fluorescent Sensor for Rapid Early Screening of Oral Squamous Cell Carcinoma

Various types of sensors play an irreplaceable role in the detection of biomarkers, but their high cost and complicated operation make it difficult to benefit ordinary people. Herein, we develop a low-cost, double-layered, paper-based fluorescent sensor (CP/HQ) structurally consisting of the upper reaction layer loaded with two oxidases (lactate oxidase and choline oxidase) and the bottom fluorescent layer that physically associates with the porphine-grafted composite fluorescent polymer colloids (PF-PDMTP/HQ). Based on the dramatic and rapid fluorescence decrease of porphine induced by the oxidation between saliva and oxidases and subsequent fluorescence resonance energy transfer from oxidized hydroquinone, the resultant fluorescent paper sensor enables us to achieve visual detection of OSCC, which was further recognized by smartphone scanning as the grayscale variation. It was found that the linear sensing range of grayscale value are 10-200 μM for lactic acid and 10-100 μM for choline, with LODs of 5.7 and 8.9 μM, respectively. More importantly, the sensor can achieve a powerful detection capability comparable to that of high-performance liquid chromatography (HPLC) in clinical settings with simple operation, demonstrating its great application potential. Our proposed sensor not only improves the accuracy of OSCC diagnosis but also provides a valuable attempt for the device modification of polymer-sensing systems and the development of non-invasive and easy-to-operate disease screening methods.

Emulsion polymerized styrene acrylic/nanocellulose composite coating to improve the strength and hydrophobicity of kraft paper

Improving the mechanical and water repelling property of kraft paper will extend its use for packaging application. In this work, we developed a cellulose nanofiber (CNF)-based colloidal polymer nanocomposite that was used as coating for improving those properties of kraft paper. In this case, the polymer latex was obtained by the mini-emulsion copolymerization of styrene (St), 2-ethyl hexyl acrylate (EHA) initiated by ammonium persulfate. The CNFs were incorporated into the styrene-acrylic copolymer matrix by the in-situ polymerization and ex-situ mixing process keeping the CNF concentration up to 1.0 wt%. All the latexes showed particle size below 100 nm and excellent colloidal stability (Zeta potential > −32 mV) for several months. The nanocomposite films showed improved mechanical properties (tensile strength upto 7.8 MPa, elongation upto 1096 %) than the pristine copolymer. The in-situ prepared nanocomposite at 1.0 wt% CNF showed the highest storage modulus. The latex-coated kraft paper showed improved tensile index (31.0–45.1 Nm/g) compared to the uncoated paper (20.3 Nm/g) and also high hydrophobicity (water contact angle ∼120°) for the ex-situ prepared nanocomposites. The results are quite promising to develop paper-based packaging materials using nanocellulose in combination with synthetic polymers.

Effects of Polymer Molecular Weight on Structure and Dynamics of Colloid-Polymer Bridging Systems.

We investigate the effects of polymer molecular weight on the structure and dynamics of a model colloid-polymer bridging system using confocal microscopy. Polymer-induced bridging interactions between trifluoroethyl methacrylate-co-tert-butyl methacrylate (TtMA) copolymer particles and poly(acrylic acid) (PAA) polymers of molecular weight Mw of 130, 450, 3000, or 4000 kDa and normalized concentrations c/c* ranging from 0.05 to 2 are driven by hydrogen bonding of PAA to one of the particle stabilizers. At a constant particle volume fraction ϕ = 0.05, the particles form clusters or networks of maximal size at an intermediate polymer concentration and become more dispersed upon further addition of polymer. Increasing the polymer Mw at a fixed normalized concentration c/c* increases the cluster size: suspensions with 130 kDa polymer contain small clusters that remain diffusive, and those with 4000 kDa polymer form larger, dynamically arrested clusters. Biphasic suspensions with distinct populations of disperse and arrested particles form at low c/c*, where there is insufficient polymer to bridge all particles, or high c/c*, where some particles are sterically stabilized by the added polymer. Thus, the microstructure and dynamics in these mixtures can be tuned through the size and concentration of the bridging polymer.

Anti-counterfeiting ink based on polymer nanoparticles containing spiropyran and Aza-BODIPY for artificial industries

Counterfeiting in various artificial industries has been a serious challenge for the authenticity of cultural products. Security marking of original crafts with high-security anti-counterfeiting inks could be a possible way to limit counterfeiting in art products. In this study, spiropyran-containing colloidal polymer particles were synthesized using emulsifier-free emulsion polymerization. Scanning electron microscopy and dynamic light scattering were used to analyze morphology and size of the nanoparticles. Anti-counterfeiting inks based on Förster resonance energy transfer (FRET) were then formulated via physical doping of aza-BODIPY into the colloidal polymer latex samples, where the cemically incorporated spiropyran into the particles acts as the donor and aza-BODIPY plays the role of the acceptor. Fluorescence and ultraviolet-visible spectroscopy were used to evaluate the FRET process possibility and efficiency. The high-security ink was subsequently used for security marking of a special handicraft. Silk fibers were impregnated with both of the photochromic and FRET-based inks in different concentrations and used in weaving the petal patterns. This aqueous FRET-based ink could also be used for security marking of different documents and also various art products. This study could help to reduce forgery in artificial industries, for authentication of the original handicrafts form the fakes, and prevent from counterfeiting in art industries.

Injectable Colloidal Hydrogels of N-Vinylformamide Microgels Dispersed in Covalently Interlinked pH-Responsive Methacrylic Acid-Based Microgels

Injectable hydrogels offer great potential to augment damaged or degenerated soft tissues. A key criterion for such gels is that their modulus is as close as possible to that of the target tissue. The majority of synthetic hydrogels have used low molecular weight polymer chains which may cause problems if they diffuse away from the injection site and/or increase the local osmotic pressure. We previously introduced a different approach of injecting preformed ultra-high molecular weight pH-responsive microgels (MGs) that interlink to form hydrogels. MGs are crosslinked polymer colloid particles that swell when the pH approaches the particle pKa. These colloidal hydrogels are termed doubly crosslinked microgels (DX MGs). The gel moduli of previous DX MGs were much greater than that reported for human nucleus pulposus (NP) tissue of the spinal intervertebral disk. Here, we replace some of the pH-responsive poly(ethyl acrylate-co-methacrylic acid) (PEA-MAA) MGs with hydrophilic non-ionic MGs based on poly(N-vinylformamide) (NVF). We investigate the morphology and mechanical properties of these new injectable composite DX MGs and show that the mechanical properties can be tuned by systematically varying the NVF MG content. Using this approach, the gel moduli close to that for NP tissue are achieved. These injectable new pH-responsive gels exhibit low cytotoxicity. Our work provides a potential new system for minimally invasive intervertebral disk augmentation.

Critical analysis of adhesion work measurements from AFM-based techniques for soft contact

HypothesisThe work of adhesion is a thermodynamic quantity that is frequently measured by atomic force microscopy (AFM). Determination of the work of adhesion requires quasi-equilibrium measurements, where we address the question of to what extent atomic force microscopy qualifies for quasi-equilibrium measurements. ExperimentTo measure the work of adhesion, we combined soft colloidal probe AFM (SCP AFM) with reflection interference contrast microscopy (RICM). This allowed us to extract the work of adhesion either from the pull-off force or from the contact radius. With these methods, we investigated the adhesion behavior of poly(N-isopropylacrylamide) (PNIPAM) polymer brushes in the swollen and solvent-induced collapsed state by systematically analyzing contact radii and adhesive forces. FindingsIn the swollen state, the adhesion to the PNIPAM brush was fivefold larger and exhibited significant time dependencies when measured with SCP AFM. A strong rate dependence of the pull-off force method was indicative of a non-equilibrium process. In order to reliably determine the equilibrium work of adhesion, the contact radius method was found to be the better because it is not rate dependent. Our work highlights the important benefits of using optical measurements to determine the contact radius when deriving the works of adhesion between colloidal probes and polymer brush surfaces.

Polymer Colloids: Current Challenges, Emerging Applications, and New Developments.

Polymer colloids are complex materials that have the potential to be used in a vast array of applications. One of the main reasons for their continued growth in commercial use is the water-based emulsion polymerization process through which they are generally synthesized. This technique is not only highly efficient from an industrial point of view but also extremely versatile and permits the large-scale production of colloidal particles with controllable properties. In this perspective, we seek to highlight the central challenges in the synthesis and use of polymer colloids, with respect to both existing and emerging applications. We first address the challenges in the current production and application of polymer colloids, with a particular focus on the transition toward sustainable feedstocks and reduced environmental impact in their primary commercial applications. Later, we highlight the features that allow novel polymer colloids to be designed and applied in emerging application areas. Finally, we present recent approaches that have used the unique colloidal nature in unconventional processing techniques.

Role of Polyanions and Surfactant Head Group in the Formation of Polymer-Colloid Nanocontainers.

This study was aimed at the investigation of the supramolecular systems based on cationic surfactants bearing cyclic head groups (imidazolium and pyrrolidinium) and polyanions (polyacrylic acid (PAA) and human serum albumin (HSA)), and factors governing their structural behavior to create functional nanosystems with controlled properties. Research hypothesis. Mixed PE-surfactant complexes based on oppositely charged species are characterized by multifactor behavior strongly affected by the nature of both components. It was expected that the transition from a single surfactant solution to an admixture with PE might provide synergetic effects on structural characteristics and functional activity. To test this assumption, the concentration thresholds of aggregation, dimensional and charge characteristics, and solubilization capacity of amphiphiles in the presence of PEs have been determined by tensiometry, fluorescence and UV-visible spectroscopy, and dynamic and electrophoretic light scattering. The formation of mixed surfactant-PAA aggregates with a hydrodynamic diameter of 100-180 nm has been shown. Polyanion additives led to a decrease in the critical micelle concentration of surfactants by two orders of magnitude (from 1 mM to 0.01 mM). A gradual increase in the zeta potential of HAS-surfactant systems from negative to positive value indicates that the electrostatic mechanism contributes to the binding of components. Additionally, 3D and conventional fluorescence spectroscopy showed that imidazolium surfactant had little effect on HSA conformation, and component binding occurs due to hydrogen bonding and Van der Waals interactions through the tryptophan amino acid residue of the protein. Surfactant-polyanion nanostructures improve the solubility of lipophilic medicines such as Warfarin, Amphotericin B, and Meloxicam. Surfactant-PE composition demonstrated beneficial solubilization activity and can be recommended for the construction of nanocontainers for hydrophobic drugs, with their efficacy tuned by the variation in surfactant head group and the nature of polyanions.

Experimental research on the water precipitation performance of polymer colloid and fly ash colloid and their applications as fire extinguishing materials in mines

In this paper, polymer colloid and fly ash colloid fire extinguishing materials are selected. Through experimental preparation and water precipitation characteristics research, colloid fire extinguishing materials and optimal concentration ratio suitable for Binchang mining area are selected to effectively control the fire area. The results show that, the higher the concentration of polymer colloidal powder mixed with water, the shorter the gelling time. After the fly ash is mixed with the gelling agent and water, when the concentration ratio of fly ash to water remains the same, the greater the concentration of the gelling agent, the shorter the gelling time. After the colloid is left standing for 24 h, the smaller the concentration is, the more water is precipitated, and the higher the water precipitation rate is. Through comparison, it was found that when the polymer colloid was selected as the fire extinguishing material, with the concentration ratio of polymer colloid material to water being 3.5%–4%: 96.5%–96%, effective control could be achieved over the fire zones in the goaf of Binchang mine. The research is of great reference value for the control of mine fires.

Solventless Drug Pelletization and Polymer Coating Techniques for Pharmaceutical Manufacturing

This paper described a review of solventless drug pelletization and polymer coating techniques using a mechanical powder processor as well as conventional processors including a high shear granulator and a V-shaped blender. Mechanical powder processing of drug crystals provided pellets comprising drug alone and the pelletization was due to inherent adhesiveness of drug powder as well as mechanically-induced dehydration or amorphization of drug crystals. Mechanical powder coating of polymethacrylates and ethylcellulose was achieved using freeze dried powder comprising colloidal polymer particles. High shear mixing of drug crystals and cellulose spheres provided drug-layered pellets by ball-milling actions of the spheres in the granulator. V-shaped blending of uncoated tablets and colloidal polymer powder resulted in the coating of the tablets with broken polymer particles. These techniques include only simple mixing processes and need no solvents, thereby contributing to the reduction of the environment impacts and costs in pharmaceutical manufacturing.

Microgels as Smart Polymer Colloids for Sensing and Environmental Remediation

Stimuli-responsive microgels are gaining a lot of attention as a result of their excellent chemical and structural integrity with easy deformability and possibilities for being incorporated into various functionalities. The characteristic chemical and physical properties of microgels result in their widespread application. Among their many applications in the current review, we will give an overview on the design principles and synthetic approaches of microgels for sensing applications and their uses for the removal of different environmental pollutants. It is important to understanding the mechanism of sensing and adsorption, which is important for exploring further advancement. In this review, we brief these aspects.