Diblock Copolymer Poly Research Articles

Effects of Ionic Strength and Ion Specificity on the Interface Behavior of Poly(dimethylaminoethyl methacrylate)-Poly(lauryl methacrylate).

The ion specificity effect on the water solubility of poly(N-isopropylacrylamide)-containing copolymers complies with the Hofmeister series, which is applicable to other copolymers or not need to be explored. In this work, effects of ionic strength under acidic conditions and ion specificity under alkaline conditions on the air/water interface behavior of two amphiphilic diblock copolymers poly(dimethylaminoethyl methacrylate)-poly(lauryl methacrylate) (PDMAEMA-PLMA) were systematically studied. Under acidic conditions, the surface pressure-area isotherms of a predominantly hydrophilic copolymer are insensitive to ionic strength. In contrast, the isotherms of a predominantly hydrophobic copolymer successively shift to the large, small, and large molecular area with the increase of ionic strength. Under alkaline conditions, the interfacial stretch degrees of PDMAEMA chains of two copolymers change with salt species and concentrations, which do not comply with the Hofmeister series. All of the Langmuir-Blodgett films of the former copolymer exhibit separate circular micelles. Nevertheless, those of the latter copolymer obtained under alkaline conditions exhibit various distinctive morphologies such as separate circular micelles, large separate PLMA cores within large PDMAEMA domains, and large PLMA domains/aggregates surrounded by short PDMAEMA shells. It can be attributed to the high deformability of PLMA chains, the ion specificity effect on the stretch degree of PDMAEMA blocks, and their underwater solubility upon compression.

Synthesis of multiple heteroatom–doped mesoporous carbon/silica composites for supercapacitors

In this study we synthesized a series of tunable multiple heteroatom–doped mesoporous carbon/silica composites directly through a facile tricomponent co-assembly approach using a triazine–formaldehyde phenolic resol (N-resol) as the C and N atom source, tetraethyl orthosilicate (TEOS) as the Si atom source, and the diblock copolymer poly(ethylene oxide–b–ε-caprolactone) (EC) as the structure-directing template. Small-angle X-ray scattering and transmission electron microscopy revealed that mesophase transformations of the N-resol/EC/TEOS hybrids, from double-gyroid to cylinder to lamellar structures, occurred upon increasing the TEOS content (i.e., double-gyroid at 60/40/0 and 60/40/5; cylinder at 60/40/10; lamellar at 60/40/20 and 60/40/30; short-range-order structure at 60/40/50). After removing the EC template by heating sequentially at 400 and 700 °C, the resultant multiple heteroatom–doped mesoporous carbon/silica composites had high N atom (up to 13.0 wt%), O atom (up to 21.5 wt%), and Si atom (up to 6.8 wt%) contents and double-gyroid, cylinder, and wormlike mesostructures. These multiple heteroatom–doped mesoporous carbon/silica composites had exceptionally high supercapacitor efficiencies, with excellent electrochemical specific capacitances (up to 827 F g−1 at a current density of 0.5 A g−1) and very high stabilities (up to 96.64% at a current density of 10 A g−1 for up to 10 000 cycles). Such mesoporous carbon/silica composites would appear to have tremendous potential for use as high-performance supercapacitors in energy storage applications.

Stimuli-responsive polymersomes of poly [2-(dimethylamino) ethyl methacrylate]-b-polystyrene

Amphiphilic diblock copolymers may assemble in aqueous solutions to form vesicles delimited by a polymeric double layer, also known as polymersomes, considered a more robust option to liposomes. Diblock copolymers may respond to pH, temperature, and other conditions. Because of such properties, polymersomes are currently being studied as drug delivery systems or as nanoreactors. pH-responsive polymersomes are potentially crucial because unusual pH gradients are present in cells under several physiological and pathological conditions. We synthesized two diblock copolymers of poly [2-(dimethylamino) ethyl methacrylate]-block-polystyrene (PDMAEMA-b-PS) via RAFT. We both developed new materials and better-understood polymersomes' properties with pH and temperature-responsive groups with these polymers. GPC, 1H-NMR, and FTIR characterized copolymers. The ionization equilibrium of the PDMAEMA amino groups on the polymersomes was analyzed by potentiometric titration and Zeta potential measurements. The hydrodynamic radius of the polymersomes in different pH and temperatures was analyzed by DLS. Entrapment of an electron paramagnetic resonance probe indicated the presence of a hydrophilic inner core. Negative staining transmission electron microscopy showed spherical aggregates and confirmed the diameter around 80 nm. These polymersomes with dual stimulus–response (i.e., pH and temperature) may be a platform for gene delivery and nanoreactors.

Formation of Uni-Lamellar Vesicles in Mixtures of DPPC with PEO-b-PCL Amphiphilic Diblock Copolymers.

The ability of mixtures of 1.2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and the amphiphilic diblock copolymers poly (ethylene oxide)-block-poly(ε-caprolactone) (PEO-b-PCL) to stabilize uni-lamellar nano-vesicles is reported. Small angle neutron scattering (SANS) is used to define their size distribution and bilayer structure and resolve the copresence of aggregates and clusters in solution. The vesicles have a broad size distribution which is compatible with bilayer membranes of relatively low bending stiffness. Their mean diameter increases moderately with temperature and their number density and mass is higher in the case of the diblock copolymer with the larger hydrophobic block. Bayesian analysis is performed in order to justify the use of the particular SANS fitting model and confirm the reliability of the extracted parameters. This study shows that amphiphilic block copolymers can be effectively used to prepare mixed lipid-block copolymer vesicles with controlled lamellarity and a significant potential as nanocarriers for drug delivery.

Composition of α-tocopheryl acetate with micellar nanocarriers and the possibility of its use as a biologically active additive

Based on the asymmetric diblock copolymer (DBC) poly(ethylene oxide)/polyacrylic acid, effective, biocompatible and biodegradable micellar carriers were obtained for the delivery of vitamin E analogue, α-tocopheryl acetate (α-TOCA), in living organisms. The monitoring of the stability of micellar structures of the block copolymer and its composition with α-TOCA over time, in a saline solution and when the pH of the solution changes, was carried out. The stability of DBC micelles over time at pH = 3.5, partial disaggregation of micelles at pH = 9 and an increase in their aggregation in physiological solution were shown. The high stability of the α-TOCA/DBC composition formed in situ in time in the range of pH=3.5-9 and a significant decrease in its solutions of salting out effects in the presence of NaCl were established. The thermodynamic parameters of the process of the micelle formation of the pure α-TOCA in water/ethanol solution (95/5 v/v) as well as the size and morphology of its micellar structures were determined by light scattering and TEM methods. The initial α-TOCA micelles in water/ethanol solution were stable over a wide pH range, but their stability was much lower and the sensitivity to the presence of NaCl was much higher than that of DBC micelles. The dialysis method revealed the gradual release of the drug from the micellar carrier through a semipermeable membrane into the surrounding aqueous and aqueous-saline media. However, the rate and efficiency of α-TOCA release from the DBC micelles in an aqueous medium were significantly lower compared to a similar process of drug release from the pure α-TOCA dispersion. Thus, a possibility of providing of long-term controlled release of α-TOCA in the living organism due to the use of DBC micelles has been proven. Based on in vivo tests of the biological action of the composition on pregnant sows, its high bioavailability, rapid absorption, active participation in metabolic processes and positive effect on the reproductive qualities of sows compared to pure α-TOCA, were displayed, which improves the safety and productivity of newborn piglets. Key words: diblock copolymer, α-tocopheryl acetate, micellar carrier, encapsulation/release, biological action.

Hierarchical supramolecular assembly of a single peptoid polymer into a planar nanobrush with two distinct molecular packing motifs

Hierarchical nanomaterials have received increasing interest for many applications. Here, we report a facile programmable strategy based on an embedded segmental crystallinity design to prepare unprecedented supramolecular planar nanobrush-like structures composed of two distinct molecular packing motifs, by the self-assembly of one particular diblock copolymer poly(ethylene glycol)-block-poly(N-octylglycine) in a one-pot preparation. We demonstrate that the superstructures result from the temperature-controlled hierarchical self-assembly of preformed spherical micelles by optimizing the crystallization-solvophobicity balance. Particularly remarkable is that these micelles first assemble into linear arrays at elevated temperatures, which, upon cooling, subsequently template further lateral, crystallization-driven assembly in a living manner. Addition of the diblock copolymer chains to the growing nanostructure occurs via a loosely organized micellar intermediate state, which undergoes an unfolding transition to the final crystalline state in the nanobrush. This assembly mechanism is distinct from previous crystallization-driven approaches which occur via unimer addition, and is more akin to protein crystallization. Interestingly, nanobrush formation is conserved over a variety of preparation pathways. The precise control ability over the superstructure, combined with the excellent biocompatibility of polypeptoids, offers great potential for nanomaterials inaccessible previously for a broad range of advanced applications.

Secondary Structures of Polypeptide-Based Diblock Copolymers Influence the Microphase Separation of Templates for the Fabrication of Microporous Carbons

In this study, we synthesized two forms of the polypeptide-based rod–coil diblock copolymer poly(ethylene oxide-b-γ-benzyl-l-glutamate) (PEO-b-PBLG), comprising hydrophilic PEO as the coil segment ...

Study of the partition of sodium diclofenac and norfloxacin in aqueous two-phase systems based on copolymers and dextran

The partitioning behavior of norfloxacin (more hydrophilic) and sodium diclofenac (more hydrophobic) was studied considering the use of aqueous two-phase systems (ATPSs) based in copolymers and dextran. For this research, the phase behavior of systems composed of water, a copolymer (Pluronic PE6400, Pluronic L35, Pluronic PE6800, PEG-ran-PPG monobutyl ether and PEG-ran-PPG) and dextran (Mw=40000 and 6000 g.mol−1) were investigated. The phase diagrams showed that by increasing the molecular weight and the copolymer PPG/PEG ratio, the biphasic region is enlarged. After defining the bionodal curves, a preliminary screening on the partition of two pharmaceutic ingredients (sodium diclofenac and norfloxacin) was carried. After selected the most appropriate ATPS for the partition of both drugs, namely systems based on diblock copolymers (poly(ethylene glycol)-poly(propylene glycol)) – dextran T6 and one random copolymer (poly(ethylene glycol)-ran-poly(propylene glycol)) – dextran T6, the effect of the copolymer concentration and different mixture points was assessed. In the end, the results showed that by increasing the copolymer concentration and tie-line length, the partition coefficient of the pharmaceutical ingredients increased in the block copolymer-based ATPS and decreased in systems containing the random copolymer.

TME‐Responsive Polyprodrug Micelles for Multistage Delivery of Doxorubicin with Improved Cancer Therapeutic Efficacy in Rodents

It is of great significance to develop multifunctional biomaterials to effectively deliver anticancer drug to tumor cells for cancer therapy. Here, inspired by the specific tumor microenvironment (TME) cues, a unique multistage pH/redox-responsive polyprodrug composed of amphiphilic pH-sensitive diblock copolymer poly(ethylene glycol) methyl ether-b-poly(β-amino esters) conjugated with doxorubicin (DOX) via redox-sensitive disulfide bonds (mPEG-b-PAE-ss-DOX) is designed and developed. This polyprodrug can self-assemble into micelles (DOX-ss@PMs) at low concentration with high serum stability, indicating that DOX-ss@PMs have prolonged circulation time. The dual pH/redox-responsiveness of the multistage platform is thoroughly evaluated. In vitro results demonstrate that DOX-ss@PMs can highly accumulate at tumor site, followed by responding to the acidity for disassembly and effectively penetrating into the tumor cells. DOX is released from the platform due to the cleavage of disulfide bonds induced by high glutathione (GSH) concentration, thereby inducing the apoptosis of tumor cells. In vivo studies further reveal that multistage DOX-ss@PMs can more efficiently inhibit the growth of tumors and improve the survival of tumor-bearing mice in comparison to the free drug and control. These results imply that multistage delivery system might be a potential and effective strategy for drug delivery and DOX-ss@PMs could be a promising nanomedicine for cancer chemotherapy.

Fabrication of fluorine-free superhydrophobic cotton fabric using fumed silica and diblock copolymer via mist modification

Immobilizing inorganic particles to improve the roughness or coating with fluorinated agents and polysiloxanes to reduce surface energy is the most popular approach for constructing superhydrophobic cotton fabrics. However, the poor durability, health and environmental concerns, and other serious drawbacks limit the application of superhydrophobic cotton fabrics. In the present work, we describe a simple and facile fabrication strategy to construct robust fluorine-free superhydrophobic surfaces of cotton fabric via a mist technique. The modified cotton fabrics were first immobilized by fumed silica (SiO2) particles to improve the roughness and then covered with a diblock copolymer of poly[(methyl methacrylate)-b-(lauryl methacrylate)] (PMMA-b-PLMA), which was synthesized by RAFT polymerization, to reduce the fabric’s surface energy. The mist technology used ensures that the PMMA-b-PLMA covers the SiO2 particles on the surface of the fabric with a thin coating. Therefore, the SiO2 particles were stably immobilized on the fabric surface without reducing the roughness. As a result, the water contact angle (WCA) values of the prepared cotton fabrics reached reached 156.7°±0.5°. Moreover, even after 1600 abrasion cycles or 80 laundering cycles, the WCA values of the fabric samples were still higher than 150.1°±0.5°. The stable superhydrophobic cotton fabric surfaces are useful for self-cleaning, oil-water separation, and other potential areas.

Preparation of ROS-responsive core crosslinked polycarbonate micelles with thioketal linkage

Herein, we prepared novel reactive oxygen species (ROS) responsive core crosslinked (CCL/TK) polycarbonate micelles conveniently by click reaction between amphiphilic diblock copolymer poly(ethylene glycol)-poly(5-methyl-5-propargylxycar-bonyl-1,3-dioxane-2-one) (PEG-PMPC) with pendant alkynyl group and thioketal containing azide derivative bis (2-azidoethyl) 3, 3′- (propane-2, 2-diylbis (sulfanediyl)) dipropanoate (TK-N3). The CCL/TK micelles were obtained with small size of 146.4 nm, showing excellent stability against dilution and high doxorubicin (DOX) loading. In vitro toxicity tests demonstrated that the obtained CCL/TK micelles have good biocompatibility and low toxicity with cell viability above 95 %. Furthermore, DOX-loaded CCL/TK micelles showed significantly superior toxicity with IC50 values for HeLa and MCF-7 cells about 3.74 μg/mL and 3.91 μg/mL, respectively. Confocal laser scanning microscope (CLSM) and flow cytometry showed excellent internalization efficiency and intracellular drug release of DOX-loaded CCL/TK micelles. The obtained ROS-responsive CCL/TK micelles showed great potential for anticancer drug delivery.

Hybrid polymeric nanoparticles with high zoledronic acid payload and proton sponge-triggered rapid drug release for anticancer applications.

Zoledronic acid (ZA), a third-generation nitrogen-heterocycle-containing bisphosphonate, has been frequently used as an anti-resorptive agent to treat cancer-involved hypercalcemia and painful bone metastases. In order to expand the clinical applications of ZA toward the extraskeletal tumor treatment, it is essential to develop the functionalized nanocarriers capable of carrying high ZA payload and achieving intracellular triggered ZA release. In this end, the ZA-encapsulated hybrid polymeric nanoparticles were fabricated in this work by co-association of the amphiphilic diblock copolymer poly(lactic-co-glycolic acid)-b-poly(ethylene glycol) (PLGA-b-PEG), tocopheryl polyethylene glycol succinate (TPGS) segments and ionic complexes composed of ZA molecules and branched poly(ethylenimine) (PEI) segments. Notably, the ionic pairings of PEI segments with ZA molecules not only assisted encapsulation of ZA into the PLGA-rich core of hybrid nanoparticles but also reduced adhesion of ZA on the surfaces of hydrophobic cores, thus largely increasing ZA loading capacity. The dynamic light scattering (DLS) and transmission electron microscopy (TEM) characterization revealed that the ZA/PEI-loaded nanoparticles had a well-dispersed spherical shape. Moreover, compared to short PEI1.8k (1.8kDa) segments, the longer PEI10k (10kDa) segments formed more robust complexes with ZA molecules, thus prominently promoting ZA loading content of hybrid nanoparticles and their colloidal stability. Interestingly, with the suspension pH being reduced from 7.4 to 5.0, the considerable disruption of ZA/PEI ionic complexes owing to the acid-activated protonation of ZA molecules and the developed proton sponge-like effect inside the nanoparticle matrix upon the protonated PEI segments facilitated the rapid release of ZA molecules from drug-loaded hybrid nanoparticles. The results of in vitro cellular uptake and cytotoxicity studies showed that the ZA/PEI-loaded hybrid nanoparticles were internalized by MCF-7 cells upon energy-dependent endocytosis and displayed a superior cytotoxic effect to free ZA. This work demonstrates that the unique ZA/PEI-loaded hybrid polymeric nanoparticles display great promise for anticancer applications.

Bioinspired All-Polyester Diblock Copolymers Made from Poly(pentadecalactone) and Poly(2-(2-hydroxyethoxy)benzoate): Synthesis and Polymer Film Properties.

The bioinspired diblock copolymers poly(pentadecalactone)-block-poly(2-(2-hydroxyethoxy)-benzoate) (PPDL-block-P2HEB) were synthesized from pentadecalactone and dihydro-5H-1,4-benzodioxepin-5-one (2,3-DHB). No transesterification between the blocks was observed. In a sequential approach, PPDL obtained by ring-opening polymerization (ROP) was used to initiate 2,3-DHB. Here, the molar mass Mn of the P2HEB block was limited. In a modular approach, end-functionalized PPDL and P2HEB were obtained separately by ROP with functional initiators, and connected by 1,3-dipolar Huisgen reaction ("click-chemistry"). Block copolymer compositions from 85:15 mass percent to 28:72 mass percent (PPDL:P2HEB) were synthesized, with Mn of from about 30,000-50,000 g mol-1. The structure of the block copolymer was confirmed by proton NMR, FTIR spectroscopy, and gel permeation chromatography. Morphological studies by atomic force microscopy (AFM) further confirmed the block copolymer structure, while quantitative nanomechanical AFM measurements revealed that the DMT moduli of the block copolymers ranged between 17.2 ± 1.8 MPa and 62.3 ± 5.7 MPa, i.e. between the values of the parent P2HEB and PPDL homopolymers (7.6 ± 1.4 MPa and 801 ± 42 MPa, respectively). Differential scanning calorimetry showed that the thermal properties of the homopolymers were retained by each of the copolymer blocks (melting temperature 90 °C, glass transition temperature 36 °C).

Impact of Thermal History on the Kinetic Response of Thermoresponsive Poly(diethylene glycol monomethyl ether methacrylate)-block-poly(poly(ethylene glycol)methyl ether methacrylate) Thin Films Investigated by In Situ Neutron Reflectivity.

The impact of thermal history on the kinetic response of thin thermoresponsive diblock copolymer poly(diethylene glycol monomethyl ether methacrylate)-block-poly(poly(ethylene glycol) methyl ether methacrylate), abbreviated as PMEO2MA-b-POEGMA300, films is investigated by in situ neutron reflectivity. The PMEO2MA and POEGMA300 blocks are both thermoresponsive polymers with a lower critical solution temperature. Their transition temperatures (TTs) are around 25 °C (TT1, PMEO2MA) and 60 °C (TT2, POEGMA300). Thus, by applying different temperature protocols (20 to 60 or 20 to 40 to 60 °C), the PMEO2MA-b-POEGMA300 thin films experience different thermal histories: the first protocol directly switches from a swollen to a collapsed state, whereas the second one switches first from a swollen to a semicollapsed and finally to a collapsed state. Although the applied thermal histories differ, the response and final state of the collapsed films are very close to each other. After the thermal stimulus, both films present a complicated response composed of an initial shrinkage, followed by a rearrangement. Interestingly, a subsequent reswelling of the collapsed film is only observed in the case of having applied a thermal stimulus of 20 to 40 °C. The normalized film thickness and the D2O amount of each layer in the PMEO2MA-b-POEGMA300 films are consistent at the end of the two different thermal stimuli. Hence, it can be concluded that the thermal history does not influence the final state of the PMEO2MA-b-POEGMA300 films upon heating. Based on this property, these thin films are especially suitable for the temperature switches on the nanoscale, which may experience different thermal histories.

Bioinspired All-Polyester Diblock Copolymers Made from Poly(pentadecalactone) and Poly(3-hydroxycinnamate): Synthesis and Polymer Film Properties.

A bioinspired diblock copolymer was synthesized from pentadecalactone and 3-hydroxy cinnamic acid. Poly(pentadecalactone) (PPDL) with a molar mass of up to 43,000 g mol-1 was obtained by ring-opening polymerization initiated propargyl alcohol. Poly(3-hydroxy cinnamate) (P3HCA) was obtained by polycondensation and end-functionalized with 3-azido propanol. The two functionalized homopolymers were connected via 1,3-dipolar Huisgen addition to yield the block copolymer PPDL-triazole-P3HCA. The structure the block copolymer was confirmed by proton NMR, FTIR spectroscopy and GPC. By analyzing the morphology of polymer films made from the homopolymers, from a 1:1 homopolymer blend, and from the PPDL-triazole-P3HCA block copolymer, clearly distinct micro- and nanostructures were revealed. Quantitative nanomechanical measurements revealed that the block copolymer PPDL-triazole-P3HCA had a DMT modulus of 22.3 ± 2.7 MPa, which was lower than that of the PPDL homopolymer (801 ± 42 MPa), yet significantly higher than that of the P3HCA homopolymer (1.77 ± 0.63 MPa). Thermal analytics showed that the melting point of PPDL-triazole-P3HCA was similar to PPDL (89-90 °C), while it had a glass transition was similar to P3HCA (123-124 °C). Thus, the semicrystalline, potentially degradable all-polyester block copolymer PPDL-triazole-P3HCA combines the thermal properties of either homopolymer, and has an intermediate elastic modulus.

Three-Dimensional Spirals of Conjugated Block Copolymers Driven by Screw Dislocation

Three-dimensional spiral structures are common in nature but rare in nanoscale or mesoscale objects formed by self-assembly, and it is a challenge to obtain uniform and well-structured 3D spiral architecture. Here, we present a simple approach to preparation of 3D spiral micelles with conjugated diblock copolymer poly(p-phenylenevinylene)-block-poly(ethyleneglycol) by a dissolution-cooling-aging process. By controlling the concentration of the growing solution, the size of micelles can be regulated, and the transformation of assembly morphology from 2D square to 3D spiral can be realized. In view of the low crystallinity of compounds in this system, the 3D spiral structure is driven by relatively weak π–π intermolecular interactions of the conjugated core of the block copolymers. The surface potential of these 3D micelles is almost equally dispersed among the different positions of the spirals from the Kelvin probe force microscopy experiments, and the conductivity of the 3D spiral is inversely proportional to the numbers of spiral layers. Based on their electrical response features, these 3D spiral architectures composed of conjugated block copolymers, especially with well-controlled nanoscale sizes, should be a very promising candidate for the future photoelectronic device and switch applications.

Janus Colloidal Dimer by Intramolecular Cross-Linking in Concentrated Solutions

We propose a new method to large-scale synthesize polymeric colloidal dimers by electrostatically-mediated intramolecular cross-linking of an example di-block copolymer of poly(isoprene)-b-poly(vinylpyridine) (PI-b-P4VP) in highly concentrated solutions. The synthesis is orthogonally performed in a highly polar solvent such as DMSO. The first colloid is achieved by intramolecular cross-linking of the PI block with 1,6-hexanediisothiocyanate after modification with 2-mercaptoethylamine hydrochloride to introduce an electrostatic interaction. The Janus single-chain nanoparticle of cPI-P4VP is derived. In the sequential step, the other colloid is achieved by intramolecular cross-linking the P4VP block of cPI-P4VP with 1,5-diiodopentane after modification with iodoethane. The polymer colloidal dimer of cPI-cP4VP is thus achieved. The Janus cPI-cP4VP dimer is composed of two different domains: the cPI containing residual amine and cyanate groups and the cP4VP containing residual pyridine and quaternized groups. The dimer can be synthesized at a higher concentration of 100 mg/mL. A huge family of functional colloidal dimers is expected after selectively loading materials within the desired colloidal domains.

Coassembly behavior and kinetics of cellulose nanocrystals and pH-responsive diblock copolymers PMMA-b-PDEAEMA at oil/water interfaces and applied on the liquid tubule formation

In this work, a series of oil soluble diblock copolymers poly(methyl methacrylate)-b-poly[2-(dimethylamino)ethyl methacrylate] (PMMAm-b-PDEAEMAn; where m is fixed at 49 and n is varied from 3 to 12) are synthesized using a reversible addition-fragmentation chain transfer RAFT method. The copolymers exhibit pH-dependant interfacial activities and behave as macromolecular surfactants under strong acidic conditions. The coassembly behavior and kinetics of cellulose nanocrystals (CNCs) and the copolymer at the water/toluene interface is probed by tracking the dynamic interfacial tension using pendant drop tensiometry. At low pH such as 2 and 3, the film that CNCs coassemble with the copolymer at the oil/water interface can stabilize the pendant drop from dripping down. At a higher pH value, CNCs enhance the interfacial activity of the copolymer through interfacial tension measured and emulsions test. When investigating the coassembly kinetics, it is found that the interfacial protonation reaction of the copolymer and absorbing at the oil/water interface is the rate-determining step and electrostatic binding with CNCs is a much faster process. Besides, the interfacial activity of PMMAm-b-PDEAEMAn is enhanced as n increases and the interfacial coassembly with CNCs is accelerated. A nanoparticle film can be formed because of the coassembly behavior of CNCs and diblock copolymers at the oil/water interface and can stabilize the liquid/liquid interface and endow the interface elastic property. Based on this property, liquid tubule can be generated through injecting CNC aqueous dispersion to copolymer toluene solution. This formation of liquid tubule opens a new platform for the additive manufacturing technique of three-dimensional printing of liquid constructs.

Main Chain-Type Block Copolymers through Atom Transfer Radical Polymerization from Double-Decker-Shaped Polyhedral Oligomeric Silsesquioxane Hybrids.

In this study, we synthesized two main chain–type block copolymers featuring hydrogen bond donor and acceptor segments through atom transfer radical polymerization (ATRP) using a bifunctionalized polyhedral oligomeric silsesquioxane (POSS) nanoparticle as the initiator. Hydrosilylation of vinylbenzyl chloride at the two corners of a double-decker silsesquioxane (DDSQ) provided the bifunctionalized benzyl chloride initiator VBC-DDSQ-VBC, which we applied as a platform to prepare a main chain–type polystyrene homopolymer (PS-DDSQ-PS), the diblock copolymer poly(styrene–b–4-vinylpyridine) (P4VP-b-PS-DDSQ-PS-b-P4VP), and the diblock copolymer poly(styrene–b–tert-butoxystyrene) (PtBuOS-b-PS-DDSQ-PS-b-PtBuOS) through sequential ATRP. Selective hydrolysis of the tert-butoxyl units of PtBuOS-b-PS-DDSQ-PS-b-PtBuOS yielded the strongly hydrogen bonding diblock copolymer poly (styrene-b-vinylphenol) (PVPh-b-PS-DDSQ-PS-b-PVPh). We used Fourier transfer infrared spectroscopy, nuclear magnetic resonance spectroscopy, size exclusion chromatography, differential scanning calorimetry, mass-analyzed laser desorption ionization mass spectrometry, and transmission electron microscopy to investigate the chemical structures, thermal behavior, and self-assembled nanostructures formed by these main chain–type block copolymers based on DDSQ.

Effects of pH on the Stimuli-Responsive Characteristics of Double Betaine Hydrophilic Block Copolymer PGLBT-b-PSPE.

We investigated the pH-responsive behavior of the carboxybetaine-sulfobetaine diblock copolymer poly(2-(2-(methacryloyloxy)ethyl)dimethylammonio)acetate-block-3-((2-(methacryloyloxy)ethyl)dimethylammonio)propane-1-sulfonate (PGLBT-b-PSPE) in aqueous solution under varying temperatures. Alongside the temperature-responsive PSPE block which induces self-assembly of polymer micelles under the upper critical solution temperature, the PGLBT motifs having protonation sites caused additional changes in the phase behaviors. In acidic conditions where the pH is lower than the pKa of PGLBT-b-PSPE, the transmittance of polymer solutions more abruptly dropped and became cloudy at higher temperatures compared to the case of salt-free solutions. There were two simultaneous diffusive modes in the turbid solutions equivalent to unimers or micelles and large aggregates over a few hundred nanometers. Unlike in neutral and basic conditions, those large aggregates did not disappear after the emergence of the polymer micelles. The trend of the temperature-responsive behavior hardly changed in the alkaline solutions; however, the critical temperature significantly decreased. The surface charge of the unimers and self-assembled objects determined by zeta potential measurement varied from neutral or negative to positive with proton addition and further positively increased below the micelle formation temperature. This indicates the cationization of PGLBT moieties and their arrangement in the outer layer of the polymer micelle surface. In spite of the positively charged outer surface, two fast and slow diffusive modes representing micelles and large clusters were repeatedly observed in acidic solutions, and to some extent, size-grown particles eventually precipitated.