Copolymer Components Research Articles

Design, Synthesis, and Performance of Photo-Responsive Liquid Crystal Polymers with Stepwise Deformation Capability.

Photo-responsive liquid crystal polymers (LCPs) have potential application value in flexible robots, artificial muscles, and microfluidic control. In recent years, significant progress has been made in the development of LCPs. However, the preparation of LCPs with continuous and controllable stepwise deformation capabilities remains a challenge. In this study, visible photo-responsive cyanostilbene monomer, UV photo-responsive azobenzene monomer, and multiple hydrogen bond crosslinker are used to prepare photo-responsive LCPs capable of achieving continuously and controllable stepwise deformation. The comprehensive investigation of the multiple light response ability and photo-induced deformation properties of these copolymers is conducted. The results reveal that in the first stage of photo-induced deformation under 470nm blue light irradiation, the deformation angle decreases with a reduction in cyanostilbene content in the copolymer component, ranging from 40° in AZ0-CS4 to 0° in AZ4-CS0. In the second stage of photo-induced deformation under 365nm UV irradiation, the deformation angle increases with the increase of azobenzene content, ranging from 0° of AZ0-CS4 to 89.4° of AZ4-CS0. Importantly, the deformation between these two stages occurs as a continuous process, allowing for a direct transition from the first-stage to the second-stage deformation by switching the light source from 470 to 365nm.

Gelation of copolymers of acrylamide and sodium acrylate upon coordination with Cu2+ ions in concentrated solutions

The phase state of Cu2+ complexes with acrylamide and sodium acrylate copolymers at different copolymer concentrations and components molar ratios was studied. The change in complex stoichiometry from 2 to 3 carboxylate groups per Cu2+ ion was detected with an increase of copolymer concentration. In the concentrated solutions of copolymers, gelation is observed upon addition of Cu2+ ions, with the lowest concentration of copper required for gelation decreasing with the increase in copolymer concentration. These hydrogels are attributed to the formation of meta-stable inter-polymer metal complexes, which are able to persist due to a low segment mobility. The phase separation of complexes is shown to be associated with the bidentate coordination of carboxylate groups to Cu2+ ions, while the hydrogels formed in concentrated solutions mostly consist of bridging structures. Gelation threshold corresponds to the second critical concentration of poly(acrylamide-co-sodium acrylate) and is lower for copolymers with the higher molecular weight. Low acrylate content in the copolymers prevents collapse of the hydrogels caused by the salting-out effect. A higher gel content can be reached by increasing the copolymer concentration or the molar ratio of copper ions to carboxylate groups, with the latter reducing the swelling degree.

Toward the production of block copolymers in microbial cells: achievements and perspectives.

The microbial production of polyhydroxyalkanoate (PHA) block copolymers has attracted research interests because they can be expected to exhibit excellent physical properties. Although post-polymerization conjugation and/or extension have been used for PHA block copolymer synthesis, the discovery of the first sequence-regulating PHA synthase, PhaCAR, enabled the direct synthesis of PHA-PHA type block copolymers in microbial cells. PhaCAR spontaneously synthesizes block copolymers from a mixture of substrates. To date, Escherichia coli and Ralstonia eutropha have been used as host strains, and therefore, sequence regulation is not a host-specific phenomenon. The monomer sequence greatly influences the physical properties of the polymer. For example, a random copolymer of 3-hydroxybutyrate and 2-hydroxybutyrate deforms plastically, while a block copolymer of approximately the same composition exhibits elastic deformation. The structure of the PHA block copolymer can be expanded by in vitro evolution of the sequence-regulating PHA synthase. An engineered variant of PhaCAR can synthesize poly(D-lactate) as a block copolymer component, which allows for greater flexibility in the molecular design of block copolymers. Therefore, creating sequence-regulating PHA synthases with a further broadened substrate range will expand the variety of properties of PHA materials. This review summarizes and discusses the sequence-regulating PHA synthase, analytical methods for verifying block sequence, properties of block copolymers, and mechanisms of sequence regulation. KEY POINTS: • Spontaneous monomer sequence regulation generates block copolymers • Poly(D-lactate) segment can be synthesized using a block copolymerization system • Block copolymers exhibit characteristic properties.

Structural-property relationship in poly(vinyl aniline-co-maleic anhydride) for effective Hg2+ ions adsorption

Suitable functional modification of a polymer significantly influences its targeted applicability. Herein, we report new crosslinked copolymer synthesized from 4-vinylaniline (VA) and maleic anhydride MA) using adipic acid (AA) as the crosslinking agent, poly(VA-co-MA)-cl-AA where -co- stands for copolymer and -cl- for crosslinked. The poly(MA) component of as-synthesized copolymer was further hydrolyzed to form a new copolymer with pendant carboxyl groups. Both the copolymers, the as-synthesized and its hydrolyzed derivative, were evaluated as Hg2+ ions adsorbents. The adsorption capacity (q) was studied by variation of various adsorption parameters. The copolymer exhibited excellent Hg2+ ions adsorption (qmax = 202.43 mg g-1) with high cumulative q value (1151.3 mg g-1) in multiple cycles. The present work reveals important aspects of simple structural and functional modification of polymers achieved through simple polymer analogous reactions significantly influence their targeted applications. The findings documented in this report indicate the existence of crucial structure-activity relationship in polymer action and can be handy in designing more selective and efficient materials in future.

Multicolor‐Tunable and Time‐Dependent Circularly Polarized Room‐Temperature Phosphorescence from Liquid Crystal Copolymers

AbstractCircularly polarized luminescent (CPL) materials have significant promising applications in organic light‐emitting diodes, asymmetric synthesis, and other fields. However, due to the instability of triplet‐state excitons, how to achieve an effective combination of CPL with room‐temperature phosphorescence (RTP) remains a formidable challenge. Here, a simple and feasible method for constructing polymer‐based CPRTP materials is proposed by preparing chiral phosphorescent liquid crystals through copolymerization. A series of RTP chiral liquid crystal copolymers are successfully synthesized by copolymerizing phosphorescent monomer bearing chiral cholesterol mesogen with phosphorescent monomer bearing dibenzofuran chromophore. Due to the introduction of chiral cholesterol mesogen, copolymers can form chiral smectic C‐phase liquid crystals. Utilizing their selective reflection characteristic, efficient CPRTP is achieved, with a glum value of up to −1.6 × 10−2. In addition, both components in copolymers exhibit RTP properties and show significant differences in phosphorescence color and lifetime. By changing the composition of copolymers, the regulation of their phosphorescence properties is successfully achieved. As a result, multicolor‐tunable and time‐dependent CPRTP materials are successfully prepared.

Rearrangement and morphological transition of DNA on adsorbent templates of hydrocarbon/fluorocarbon phase‐separated monolayers

AbstractA phase‐separated template prepared from a mixed monolayer of fluorinated long‐chain s‐triazine derivatives and comb copolymers containing s‐triazine rings was morphologically controlled by DNA adsorption. The adsorbed morphology of DNA was formed through a morphological transition process at the air/water interface rather than by maintaining the shape of the phase‐separated template. Dot‐like domains, circular domains, centrally protruding domains, network morphologies, and even co‐continuous surface morphologies of DNA were obtained. The phase‐separated monolayer used as a template depends on the mixed ratio of the fluorocarbon and hydrocarbon copolymer components, the copolymerization ratio of the hydrocarbon copolymers, and the chain length of the fluorinated long‐chain s‐triazine derivative, and various morphological transitions occur. The DNA introduced into the sub‐phase was selectively adsorbed onto the s‐triazine ring‐containing comb copolymer, and the adsorbed DNA assembly exhibited a morphological transition based on concerted interactions. Furthermore, by utilizing a fluorescent probe molecule, evidence of DNA morphogenesis itself was supported by its emission/quenching behavior.Highlights Morphological control of the DNA assembly was attained. Immobilization of DNA assemblies on phase‐separated templates was achieved. Preparation of patterned templates was realized by copolymers a fluorinated derivative. Adsorption of DNA to the diamino‐s‐triazine ring was achieved by hydrogen bonding. A rearrangement of the DNA assemblies on the template was achieved.

Instant dispersion of titanium dioxide in waterborne coatings by pinning polyacrylate nanospheres

Titanium dioxide (TiO2) with 200–400 nm diameter is an important pigment in waterborne coatings. The effective dispersion of TiO2 is a significant factor in achieving outstanding coating performance. This paper presents a novel “Instant TiO2” powder by pinning a small number of polyacrylate nanospheres (less than 5 wt%) on TiO2, which can be rapidly dispersed in water within 4 s, similar to instant coffee. The polyacrylate nanospheres copolymerized with Methyl methacrylate (MMA) and 2-Hydroxyethyl methacrylate (HEMA), are connected to the surface of TiO2 via bridge linking of silane coupling agent. This technique prevents TiO2 particles from aggregation and enables rapid dispersion of TiO2 particles in water or waterborne coating. The hydrophilic groups on HEMA facilitate the nanospheres unfolding in water to form a uniform and stable TiO2 slurry, exhibiting a significantly low viscosity (101.2 mPa·s at 200 s−1) when the concentration of TiO2 as high as 70 wt%. The “instant TiO2” denoted as TiO2-MPS-PMH shows excellent coating performance, such as impressive hiding power, and long-term storage stability under 50 °C for 28 days. Pinning polyacrylate nanospheres offers a novel approach to increase dispersion and reduce energy consumption during production in waterborne coatings by the simplified coating process. This technique also provides a potential strategy for achieving the dispersion of TiO2 in various coatings by adjusting the copolymer's components with different wettability.

Disappearance of Melt Memory Effect with Comonomer Incorporation in Isodimorphic Random Copolyesters.

Melt memory effects in polymer crystallization have attracted much attention in the past few years. Although progress has been made in understanding how the chemical structure of polymers can affect melt memory, there are still some knowledge gaps. In this work, we study how incorporating a second comonomer unit that is partially included in the crystalline unit cell affects the melt memory effect of the major component in a random isodimorphic copolymer for the first time. This second comonomer unit depresses the melting temperature of the homopolymer, reduces the crystallinity, and distorts the crystalline unit cell. However, its effect on the stability of self-nuclei and the production of melt memory has not been studied so far. To this aim, we have selected poly[(butylene succinate)-ran-(ε-caprolactone)] random copolyesters PBS-ran-PCL that are isodimorphic, i.e., they exhibit a pseudoeutectic point. This point separates the formation of BS-rich crystals from CL-rich crystals as a function of composition. The results reveal that the melt memory effect of these isodimorphic copolymers is strongly reduced with the incorporation of even very small amounts of comonomer unit (i.e., 1 molar %). This indicates that the incorporation of a second comonomer unit in the polymer chain disrupts the intermolecular interactions present between the chain segments in the crystal lattice of the major component and reduces the capacity of the material to produce self-nuclei. This reduction is more drastic for copolymers in which the second comonomer unit is mostly rejected from the crystalline phase. Contrary to olefin-based copolymers, for copolyesters, the second comonomer unit eases the process to reach an isotropic melt state upon melting. This work reveals the impact of introducing comonomer units on the melt memory effect in isodimorphic random copolyesters.

Photothermal-Driven Polymer for a Smart Window with Adaptive Solar Modulation.

Although the thermochromic smart windows with adjustable sunlight transmittance to achieve energy savings are gradually improving, they are still difficult to use, limited by their unreasonable thermal response temperature, slow switching time, and poor durability. Here, we demonstrate a dual-function hybrid thermoresponsive smart window device (CPH) by trapping the phase-change polyHEA-HDA polymer (HEA = hydroxyethyl acrylate, HDA = hexadecyl acrylate) and polydopamine@CsxWO3 (PDA@CWO) core-shell nanoparticles within glasses. The introduced PDA@CWO nanoparticles substantially increase the energy transformation efficiency of solar energy to heat due to their outstanding photothermal conversion. When the temperature increases above the phase-transition temperature of polyHEA-HDA polymer, the copolymer components in the composite material undergo a reversible crystalline-amorphous transition, which enables the transformation of the whole smart window from transparency to opaque in a low ambient temperature. The light transmittance in the solar range can be dynamically modulated between 54.8 and 22.9% with a low ambient temperature while maintaining acceptable visible light transparency and effective UV shielding. A model house testing proves an indoor temperature cooling of 7.1 °C. This study offers a new approach to designing an energy-saving smart window system with multifunctionality.

Long Lifetime Delayed Fluorescent Materials with Water and Temperature Tolerability Based on Charge Separation States

AbstractLong lifetime delayed fluorescent materials have great potential applications in bioimaging, anti‐counterfeiting encryption, lighting, and other fields. However, the preparation of functionalized long lifetime fluorescent materials with simple chemical structure and tunable luminescent behavior still poses significant challenges. In this article, a simple and effective method to prepare a series of long lifetime delayed fluorescent copolymers with temperature and humidity tolerance is presented. This method involves the copolymerization of 2‐bromo‐5‐hydroxybenzaldehyde derivative monomer (M1), which contains electron‐withdrawing groups, with naphthalimide derivative fluorescent monomer (M2), which contains electron‐donating groups. The results demonstrate that long‐range charge transfer occurs between the two components in copolymers, forming charge‐separated states that emit long lifetime delayed fluorescence after exciton recombination. The delayed luminescent behavior of the copolymer is directly influenced by the content of the M2 component. The maximum delayed fluorescence lifetime can reach 13.7 ms, and the fluorescence quantum yield is 39%. Interestingly, the polymer film of P3 can emit a maximum afterglow of 1.00 s after photoactivation. Even after being immersed in water for 49 days, the afterglow remains unchanged. Besides, the afterglow of P3 can exist for ≈0.43 s at 323 K. Even at 373 K, the afterglow for 0.2 s can still be observed.

Simulation of Membrane Fabrication via Solvent Evaporation and Nonsolvent-Induced Phase Separation.

Block copolymer membranes offer a bottom-up approach to form isoporous membranes that are useful for ultrafiltration of functional macromolecules, colloids, and water purification. The fabrication of isoporous block copolymer membranes from a mixed film of an asymmetric block copolymer and two solvents involves two stages: First, the volatile solvent evaporates, creating a polymer skin, in which the block copolymer self-assembles into a top layer, comprised of perpendicularly oriented cylinders, via evaporation-induced self-assembly (EISA). This top layer imparts selectivity onto the membrane. Subsequently, the film is brought into contact with a nonsolvent, and the exchange between the remaining nonvolatile solvent and nonsolvent through the self-assembled top layer results in nonsolvent-induced phase separation (NIPS). Thereby, a macroporous support for the functional top layer that imparts mechanical stability onto the system without significantly affecting permeability is fabricated. We use a single, particle-based simulation technique to investigate the sequence of both processes, EISA and NIPS. The simulations identify a process window, which allows for the successful in silico fabrication of integral-asymmetric, isoporous diblock copolymer membranes, and provide direct insights into the spatiotemporal structure formation and arrest. The role of the different thermodynamic (e.g., solvent selectivity for the block copolymer components) and kinetic (e.g., plasticizing effect of the solvent) characteristics is discussed.

The Energy Characteristics of the Surface of Statistical Copolymers.

The results of systematic studies on the surface energy γ and its polar γP and dispersion γD components of statistical copolymers of styrene and butadiene, acrylonitrile and butadiene, and butyl acrylate and vinyl acetate, with regard to their thermal prehistory, are generalized. Along with copolymers, the surfaces of their composing homopolymers were examined. We obtained the energy characteristics of the adhesive surfaces of copolymers that contacted with air, high-energy aluminium Al (γ = 160 mJ/m2), and the low-energy substrate surface of polytetrafluoroethylene F4 (PTFE) (γ = 18 mJ/m2). The surfaces of copolymers in contact with air, aluminium, and PTFE were investigated for the first time. It was found that the surface energy of these copolymers tended to occupy an intermediate value between the surface energy of the homopolymers. The additive nature of the change in the surface energy of the copolymers with their composition, as previously established in the works of Wu, extends to the dispersive component of the free surface energy γD and the critical surface energy γcr, according to Zisman. It was shown that a significant influence on the adhesive activity of copolymers was exerted by the substrate surface upon which the adhesive was formed. Thus, for the butadiene-nitrile copolymer (BNC) samples formed in contact with a high-energy substrate, their surface energy growth was associated with a significant increase in the polar component of the surface energy γP from 2 mJ/m2 for the samples formed in contact with air, to an increase from 10 to 11 mJ/m2 for the samples formed in contact with Al. The reason why the interface influenced the change in the energy characteristics of the adhesives was the selective interaction of each macromolecule fragment with the active centres of the substrate surface. As a result, the composition of the boundary layer changed and it became enriched with one of the components. The structure of such layers is nonequilibrium. The thermal annealing of copolymers in the mode of a stepwise temperature increase led to a convergence in the values of γ, asymptotically tending to the value characteristic of the surface of the copolymers formed in air. The activation energies for the processes of the conformational rearrangements of the macromolecules in the surface layers of the copolymers were calculated. It was found that the conformational rearrangements of the macromolecules in the surface layers occurred as a result of the internal rotation of the functional groups that determined the polar component of the surface energy.

From physical mixtures to block copolymer: Impose outstandingly toughening and flame retardant effect to polypropylene

To explore new flame retardant molecules with higher flame retardancy and toughening effect, a series of non-halogen block copolymer flame retardants PAPO-MP were designed and synthesized. Importantly, compared with the control sample 24(7PAPP/3MPP)/76PP in which the intumescent flame retardant was physically blended, the mechanical properties of 24(7PAPO-3MP)/76PP with the block copolymer was greatly increased. Its impact strength and elongation at break of 24(7PAPO-3MP)/76PP were 55.1 kJ/m2 and 140.6%, increased by 166% and 965% in contrast to those of 24(7PAPP/3MPP)/76PP, respectively. Because the block copolymerized structure led to the low crystalline degree, 7PAPO-3MP can change its particle shape from lamellar to water droplet morphology during thermal processing, which contributed to better compatibility and stronger interaction with PP matrix under the action of maleic anhydride grafted polypropylene, thereby dramatically enhancing the mechanical properties of PP composites. When the addition amounts of 7PAPO-3MP were 20 wt% and 24 wt% in polypropylene (PP) composite, the two flame retardant PP composites all passed UL94 V-0 rating and had the LOI values of 28.1% and 30.2%, respectively. Their peak of heat release rate values was all decreased by over 81% compared with that of neat PP. Moreover, their total heat release and average effective heat of combustion were also decreased and brought higher residue yields. Moreover, the more release of P-containing components in block copolymer also imposed more effective gas-phase quenching effect and flame inhibition effect during combustion. The research on the block copolymer in PP composites revealed a superior way to construct high-performance non-halogen polyolefin materials.

Theoretical treatment of complex coacervate core micelles: structure and pH-induced disassembly.

Complex coacervate core micelles (C3Ms) are supramolecular soft nanostructures formed by the assembly of a block copolymer and an oppositely charged homopolymer. The coacervation of the charged segments in both macromolecules drives the formation of the core of the C3M, while the neutral block of the copolymer forms the corona. This work introduces a molecular theory (MOLT) that predicts the internal structure and stimuli-responsive properties of C3Ms and explicitly considers the chemical architecture of the polyelectrolytes, their acid-based equilibria and electrostatic and non-electrostatic interactions. In order to accurately predict complex coacervation, the correlations between charged species are incorporated into MOLT as ion-pairing processes, which are modeled using a coupled chemical equilibrium formalism. Very good agreement was observed between the experimental results in the literature and MOLT predictions for the scaling relationships that relate the dimensions of the micelle (aggregation number and sizes of the micelle and the core) to the lengths of the different blocks. MOLT was used to study the disassembly of the micelles when the solution pH is driven away from the value that guarantees the charge stoichiometry of the core. This study reveals that very sharp disassembly transitions can be obtained by tuning the length or architecture of the copolymer component, thereby suggesting potential routes to design C3Ms capable of releasing their components at very precise pH values.

Rheology, morphology and phase behavior of SBS/sulfur modified asphalt based on experimental assessment and molecular dynamics

ABSTRACT Past studies broadly discussed the effect of sulfur on the rheological properties of styrene–butadiene–styrene (SBS) modified asphalt, while the relationships between the rheological properties and phase behaviour of SBS-modified asphalt after sulfur vulcanisation have received less attention, which limits the further understanding of the relations between the structure and performance. To this end, this paper is aimed to discuss viscoelastic response at the molecular level and reveal the enhancement mechanism of SBS-modified asphalt after adding sulfur. Thus, the morphology, phase structure, and rheological behaviour of SBS/Sulfur modified asphalt were investigated by experimental assessment and molecular dynamics. Based on the results, it was found that the polybutadiene segments in SBS copolymer are the leading reactive site of vulcanisation, the interactions between SBS copolymer and light components were enhanced by sulfur treatment, the orderliness of asphalt molecules in SBS/sulfur modified asphalt was strengthened, and SBS copolymer presents a stronger attraction to aromatic after vulcanisation, which means the increase of boundary layer is also the significant cause to the improvement of compatibility. The findings are expected to deepen understanding of the vulcanisation mechanism and the rheological behaviour of SBS/Sulfur modified asphalt.

Copolymers induced co-assembly for constructing novel micellar carriers by computer simulations

Copolymers induced co-assembly to construct multifunctional drug delivery carriers is a promising strategy in biomedicine applications. Herein, the effect of the physicochemical properties of the tuned copolymers on co-assembly is systematically investigated by using dissipative particle dynamics simulations. We find the co-assembly depends heavily on the component and concentration of the tuned copolymers, as well as the interaction between the components of the mixed copolymers. These findings indicate that the tuned copolymers are a powerful tool to regulate the properties of co-assembly micelles, which may offer some significant insights into the experimental design of micellar carriers in biomedicine applications.

Reverse Engineering of Chemically Similar Bimodal High Density Polyethylenes: A Comprehensive Study Using Advanced Chromatographic Techniques

AbstractBimodal high‐density polyethylene (bHDPE) is a complex, multicomponent polyethylene (PE) material whose synthesis in a multistage process can be challenging. Three bHDPEs with good and bad end‐use properties are reverse engineered using advanced analytical techniques. Average chemical composition is determined using 13C NMR and 1‐butene is identified as the comonomer for the good resin (bHDPE 1) while 1‐hexene is the comonomer in bHDPE 2 and 3. The presence of comonomer in the high molar mass fractions of the samples is shown using high‐temperature triple‐detection size exclusion chromatography (HT‐SEC‐d3). Chemical composition separation using high‐temperature interaction chromatography (HT‐IC) is achieved using porous graphitic carbon (PGC) and silica stationary phases. Some problems in temperature gradient interaction chromatography (TGIC) on PGC are overcome by using a non‐adsorptive stationary phase, enabling better separation and visualization of homopolymer and copolymer components. Coupling HT‐SEC in 2D liquid chromatography (2D‐LC) analyses at high temperatures reveals the presence of a larger copolymer component in bHDPE 1 at high elution volume. In contrast, bHDPE 2 and bHDPE 3 have copolymer components at low elution volumes, indicating poor comonomer distribution in the copolymer component which ultimately explains the poor mechanical properties at similar comonomer contents.

Effect of nanofillers on polyurethane/polystyrene matrix nanocomposites: Characteristics and forthcoming developments

Polyurethane and polystyrene are significant thermoplastic polymers having unique physical properties. This article considers the research trials on the fabrication, remarkable features, and technical applications of the polyurethane/polystyrene nanocomposites. The carbonaceous nano particles and inorganic nanofillers used with the polyurethane/polystyrene blend or copolymer are carbon nanotube, graphene, nanoclay, silica nanoparticles, and others. The considerable improvements in the physical properties of the polyurethane/polystyrene blend may occur through the nanofiller addition. The physical or covalent interactions between the blend or copolymer components and nanofillers may also positively affect the nanocomposite properties. The fabrication strategies used for the polyurethane/polystyrene nanocomposites include solution method, in situ method, melt blending, and several nanocomposite processing approaches. The structure, morphology, electrical conductivity, thermal stability, mechanical strength, and several other physical properties of the high performance polyurethane/polystyrene nanocomposites have been explored. Major application areas identified are shape memory, membrane, and gas transport properties.

Complex Polymeric Microstructures with Programmable Architecture via Pickering Emulsion-Templated In Situ Polymerization.

Aside from smooth and spherical microcapsules, the concept of tailoring complex polymeric microstructures is being taken a step ahead due to their great demand in various applications and fundamental studies in the subjects of microfluidics and nanotechnology. Size, shape, and morphology are of paramount importance for their functional performance and various applications. However, simple, inexpensive, versatile, and high-throughput techniques for fabricating microcapsules with controlled morphology remain a bottleneck for discoveries in the subject of polymer colloids. In this paper, we directly fulfill this need by reporting a novel approach of Pickering emulsion-templated in situ polymerization for tailoring complex polymeric microstructures comprised of a composite shell of titanium dioxide nanoparticle (TiO2 NP)-embedded poly(melamine-urea-formaldehyde) (polyMUF) and a core of hexadecane (HD, soft template). At first, we hydrophobize TiO2 NPs by chemisorbing long-chain biobased myristic acid via a bidentate chelating complex and precisely tune their wettability by varying the grafting density of myristic acid to obtain highly stable oil-in-water (O/W) Pickering emulsion. Thereafter, we employ the optimized TiO2 NPs in the intended encapsulation strategy that enables various microstructures and morphologies with the particle diameter ranging from 5 to 20 μm. Careful manipulation of reaction parameters and copolymer components leads to novel complex microstructures: smooth, raspberry-like, partially budded, hollow, filled, single-holed, and closed-cell-like microstructures. Particle properties such as morphology, size, shell thickness, and core content are governed by the TiO2 NP content, core-to-shell ratio, copolymer component, conversion, and pH value. Based on the results of a series of control experiments, novel mechanisms for the formation of various such microstructures are proposed.

Multiple strategies to control the hydrophilic-hydrophobic balance of P(DMA-co-DMAEMA-co-QDMAEMA) coatings.

The regulation of the hydrophilic-hydrophobic balance of polymers has an important influence not only on their aggregation behavior in aqueous solution, but also on their adhesion properties on the surface of substrates and the applications of the modified surfaces. Based on this, a random copolymer poly(dopamine methacrylamide-co-2-(dimethylamino)ethyl methacrylate) (P(DMA-co-DMAEMA)) was synthesized as a starting polymer to generate P(DMA-co-DMAEMA-co-QDMAEMA) (PDDQ) derivatives by a programmable quaternization of the DMAEMA precursor. By adjusting the pH or temperature, both the aggregation behavior in aqueous solutions and the surface adhesive behavior on the substrate surfaces of PDDQ copolymers were regulated due to the hydrophilic-hydrophobic balance. Specifically, the surface adsorption of PDDQ copolymers on surfaces was enhanced by the increased hydrophobicity of PDDQ. Stainless steel meshes (SSM) modified with the PDDQ0 copolymer without quaternization showed a superoleophobicity in acidic aqueous media, which endowed it with improved oil-water separation performance. In addition, the hydrophilic-hydrophobic balance of PDDQs and their coatings could also be tuned by changing the ratio of DMAEMA to QDMAEMA in the copolymer. From PDDQ0 to PDDQ100, by increasing the hydrophilic QDMAEMA component of PDDQ copolymers, anti-protein properties and oil/water separation efficiency of the modified surfaces were also enhanced gradually. The results provided a reference for designing P(DMA-co-DMAEMA-co-QDMAEMA) coatings in different application environments.