Structure Of Diblock Copolymers Research Articles

Spatially Amplified and Rigid Junction in Diblock Copolymers: Reduced Microphase Separation Size via Interface Expansion.

We introduce an approach in diblock copolymer design, where modifying the junction point with rigid bulky monomer expands the cross-sectional area of the interface and leads to a decrease in the repeat period. Using living anionic polymerization, we synthesized a series of dialkynyl midfunctionalized poly(styrene-b-methyl methacrylate) (PSM-DA) and functionalized them using the thiol-alkyne click reaction with specifically selected rigid bulky monomers: PSS-(3-mercapto)propyl-heptaisobutyl substituted (PSS) and 1-adamantanethiol (ADA). This modification, though involving only a single monomer unit within the diblock copolymer structure, brought about a significant reduction in domain size, with PSS and ADA reducing it by 18% and 15%, respectively. The results indicate a method for reducing the domain sizes of block copolymers, which could lead to advancements in lithography and various nanotechnological applications.

Development of a deep-learning model for phase-separation structure of diblock copolymer based on self-consistent field analysis

Self-consistent field (SCF) analysis is an indispensable tool for predicting the microphase separation structures of polymer alloys. However, the computation of the phase-separated structures in the equilibrium state is computationally intensive, leading to high costs. To address this challenge, we propose a novel deep learning approach that leverages a generative adversarial network (GAN), a powerful deep generative model, to accelerate SCF analysis. Specifically, we trained the GAN using comprehensive data obtained from SCF analysis, enabling us to generate various images of feasible structures that are similar to the SCF analysis results. Our results demonstrate that the latent variables in the GAN are linked to the physical parameters and features of the phase-separation structures.

Amphiphilic polylactic acid-b-poly(N-(3-aminopropyl) methacrylamide) copolymers: Self-assembly to polymeric micelles for gene delivery

In this study, for the first time diblock copolymers of PLA-b-PAPMA with three different sizes were synthesized in order to fabricate cationic micelles. In this copolymer, p(APMA) block with hydrophilic cationic nature could serve as a nucleic acid condensation platform as well as the shell of micellar structure in the self-assembly process. The p(APMA) block was electrostatically complexed with nucleic acid, and formed a neutral or mildly positive charge micellar surface, thus providing the nanoparticles safety and stability. On the other hand, polylactic acid as a hydrophobic polymer in diblock copolymer structure formed core of micelles which could encapsulate hydrophobic therapeutics. The synthesized copolymers, PLA74-b-PAPMA14, PLA121-b-PAPMA22, PLA121-b-PAPMA103 were evaluated in terms of self-assembly capability, size, polydispersity index, plasmid condensation, transfection efficacy and cytotoxicity against C26 cells. Obtained results demonstrated low CMC values for all copolymers. PLA121-b-PAPMA103 diblock copolymer condensed green fluorescent protein plasmid at C/P 1 and higher, while other diblock copolymers were able to condense plasmid above C/P 70. The self-assembly structures of cationic micelles before and after plasmid condensation showed spherical morphology in SEM analysis while DLS data illustrated appropriate size (161.7 ± 8) and PDI (0.276) for PLA121-b-PAPMA103 diblock copolymer. It could be concluded that the cationic micelles with approximately the molecular weight ratio of hydrophilic block to total polymer mass of 60 % and larger than 50 % provided higher stability, condensation ability and transfection efficiency which could be attributed to the better self-assembly process and better amine groups exposure on the micellar surface.

Formation of diblock copolymer nanoparticles: Theoretical aspects

We explore the shape and internal structure of diblock copolymer (di-BCP) nanoparticles (NPs) by using the Ginzburg-Landau free-energy expansion and the dynamic self-consistent field theory (DSCFT). The self-assembly of di-BCP lamellae confined in emulsion droplets can form either ellipsoidal or onion-like NPs. The corresponding inner structure is a lamellar phase that is either perpendicular to the ellipsoid long axis (L⊥) or forms a multi-layer concentric shell (C∥), respectively. We focus on the effects of the interaction parameters between the A and B monomers χ, and polymer/solvent χPS, as well as the NP size on the nanoparticle shape and internal morphology. The aspect ratio (lAR), defined as the length ratio between the long and short axes, is used to characterize the overall NP shape. Our results show that when the solvent is neutral towards the two blocks, the ratio lAR increases as χ increases, indicating that the NP becomes more elongated. Likewise, decreasing χPS or increasing the NP size also results in a more elongated NP. Furthermore, as the solvent preference towards one of the A or B blocks increases, the NP undergoes a shape transition from a striped ellipsoid (L⊥) to onion-like sphere (C∥). Our results are in good agreement with previous experiments, and some of the predictions could be tested in future experiments.

Light‐Gated Control of Conformational Changes in Polymer Brushes

AbstractHerein, a strategy to control conformational changes in grafted polymer brushes via photoinduced crosslinking of photoreactive groups embedded into the lateral architecture of a polymer brush is reported. Poly(methylmethacrylate)‐based polymer brushes containing UV‐light (λ = 325 nm) photoreactive o‐methyl benzaldehyde moieties are synthesized using surface‐initiated reversible deactivation polymerization. The conformational changes in polymer brushes upon UV‐light triggered crosslinking are comprehensively analyzed through a full suite of surface sensitive characterization methods including time of flight secondary ion mass spectrometry, quartz crystal microbalance with dissipation monitoring, UV/vis spectroscopy, atomic force microscopy, nanoplasmonic sensing, and neutron reflectometry. The spatiotemporal control of the induced conformational changes is demonstrated via photolithography experiments. To enable an additional level of control, a second gate, the visible light (λ = 445 nm) active styrylpyrene moiety, is incorporated into the polymer brush architecture. Critically, wavelength‐selective crosslinking behavior is observed in the diblock copolymer structures allowing to crosslink specific sections of the lateral brush architecture as a function of irradiation wavelength.

Rational Design of Amphiphilic Diblock Copolymer/MWCNT Surface Modifiers and Their Application for Direct Electrochemical Sensing of DNA.

We demonstrate the application of amphiphilic ionic poly(n-butylmethacrylate)-block- poly(2-(dimethylamino)ethyl methacrylate) diblock copolymers (PnBMA40-b-PDMAEMA40, PnBMA40-b-PDMAEMA120, PnBMA70-b-PDMAEMA120) for dispersing multiwalled carbon nanotubes (MWCNTs) in aqueous media, a subsequent efficient surface modification of screen-printed electrodes (SPEs), and the application of the modified SPEs for DNA electrochemistry. Stable and fine aqueous dispersions of MWCNTs were obtained with PnBMAx-b-PDMAEMAy diblock copolymers, regardless of the structure of the copolymer and the amount of MWCNTs in the dispersions. The effect of the diblock copolymer structure was important when the dispersions of MWCNTs were deposited as modifying layers on surfaces of SPEs, resulting in considerable increases of the electroactive surface areas and great acceleration of the electron transfer rate. The SPE/(PnBMAx-b-PDMAEMAy + MWCNT) constructs were further exploited for direct electrochemical oxidation of the guanine (G) and adenine (A) residues in a model salmon sperm double-stranded DNA (dsDNA). Two well-defined irreversible oxidation peaks were observed at about +600 and +900 mV, corresponding to the electrochemical oxidation of G and A residues, respectively. A multi-parametric optimization of dsDNA electrochemistry enables one to get the limits of detection (LOD) as low as 5 μg/mL (0.25 μM) and 1 μg/mL (0.05 μM) for G and A residues, respectively. The achieved sensitivity of DNA assay enables quantification of the A and G residues of dsDNA in the presence of human serum and DNA in isolated human leukocytes.

Switch It Inside-Out: “Schizophrenic” Behavior of All Thermoresponsive UCST–LCST Diblock Copolymers

This feature article reviews our recent advancements on the synthesis, phase behavior, and micellar structures of diblock copolymers consisting of oppositely thermoresponsive blocks in aqueous environments. These copolymers combine a nonionic block, which shows lower critical solution temperature (LCST) behavior, with a zwitterionic block that exhibits an upper critical solution temperature (UCST). The transition temperature of the latter class of polymers is strongly controlled by its molar mass and by the salt concentration, in contrast to the rather invariant transition of nonionic polymers with type II LCST behavior such as poly(N-isopropylacrylamide) or poly(N-isopropyl methacrylamide). This allows for implementing the sequence of the UCST and LCST transitions of the polymers at will by adjusting either molecular or, alternatively, physical parameters. Depending on the location of the transition temperatures of both blocks, different switching scenarios are realized from micelles to inverse micelles, namely via the molecularly dissolved state, the aggregated state, or directly. In addition to studies of (semi)dilute aqueous solutions, highly concentrated systems have also been explored, namely water-swollen thin films. Concerning applications, we discuss the possible use of the diblock copolymers as "smart" nanocarriers.

Bioactive Antifouling Surfaces by Visible‐Light‐Triggered Polymerization

AbstractHierarchical bioactive surfaces are created by visible‐light‐induced surface‐initiated living radical polymerization employing tris[2‐phenylpyridinato‐C2,N]iridium(III) as a photocatalyst. The hierarchical antifouling diblock copolymer structures consist of N‐(2‐hydroxypropyl)‐methacrylamide (first block) and carboxybetaine methacrylate (second block). The living nature of the polymerization is shown by a linear increase in layer thickness (as measured by atomic force microscopy) and reinitiation of the polymerization to create a patterned second block of polymer. The chemical structure of the brushes is confirmed by X‐ray photoelectron spectroscopy and attenuated total reflection Fourier transform infrared spectroscopy measurements. The block copolymer brushes demonstrate excellent antifouling properties when exposed to single‐protein solutions or to bovine serum. The second carboxybetaine block of the hierarchical antifouling structures can effectively be biofunctionalized with an anti‐fibrinogen antibody. The coated surfaces show a high affinity and specificity to fibrinogen, while preventing nonspecific adsorption from other proteins in bovine serum.

Publisher Correction: Regioselective surface encoding of nanoparticles for programmable self-assembly.

In the version of this Article originally published, the diblock copolymer structure in Fig. 2a showed a single bond between the carbon and the oxygen atoms; it should have been a double bond. This has been corrected in all versions of the Article.

Stabilizing the Ordered Bicontinuous Double Diamond Structure of Diblock Copolymer by Configurational Regularity

We investigate the formation of the ordered bicontinuous structures in a stereoregular diblock copolymer, isotactic polypropylene-block-polystyrene (iPP-b-PS), in which the minority PP block possessed isotactic configuration. This diblock displayed the conventional ordered bicontinuous double gyroid (OBDG) morphology upon heating above the crystal melting point of the iPP block from the as-cast state. The OBDG phase remained stable in the heating process up to the order–disorder transition. In the subsequent cooling process from the nearly disordered state, the OBDG phase first developed, but when the temperature was sufficiently low, an order–order transition from OBDG to the ordered bicontinuous double diamond (OBDD) phase occurred, and OBDD eventually became the dominant structure. The results attested that OBDD and OBDG represented the thermodynamically stable structure at the lower and the higher temperature, respectively, and the OBDG morphology formed in the as-cast state was metastable. The presen...

Preparation of pendant group-functionalized amphiphilic diblock copolymers in the presence of a monomer activator and evaluation as temperature-responsive hydrogels

Temperature-responsive hydrogels have been widely developed for biomedical applications. In this study, 4-benzyloxy-ε-caprolactone (CL-OBn) was synthesized and the subsequent ring opening polymerization (ROP) of ε-caprolactone (CL) and CL-OBn monomers was performed by using the hydroxyl group of methoxy polyethylene glycol (MPEG) in the presence of HCl·Et2O as a monomer activator. MPEG-b-poly (ε-caprolactone) (MC) with benzyl pendant groups (MC-OBn) was successfully obtained in almost quantitative yield and the segment ratios and molecular weights were close to the theoretical values. Deprotection of the benzyl pendant groups successfully provided MC with hydroxyl pendant groups (MC-OH). Suspensions of MC-OBn and MC-OH exhibited distinct sol-to-gel phase transitions as a function of the temperature. The sol-to-gel phase transition of the MC-OBn and MC-OH diblock copolymers depended on the type (benzyl or hydroxyl) and amount of pendant groups in the diblock copolymer structure. The pendant group on the MC-OBn and MC-OH diblock copolymers either stabilized and/or destabilized hydrophobic aggregation between the MC segments. The hydrophobic aggregation was confirmed by the detection of crystallinity in the MC-OBn and MC-OH diblock copolymer suspensions. In conclusion, MC-OBn and MC-OH diblock copolymers were successfully prepared and served as temperature-responsive hydrogels.

On the properties of poly(isoprene-b-ferrocenylmethyl methacrylate) block copolymers

By combining poly(1,4-isoprene) (PI) with poly(ferrocenylmethyl methacrylate) (PFMMA) in a diblock copolymer structure by means of anionic polymerization we obtained narrowly dispersed PI-b-PFMMA copolymers with molecular weight ranging from 13000 to 62000 g/mol. The products were stable up to 228 °C, according to thermal gravimetry, which allowed us to further investigate their viscoelastic and X-ray scattering properties at elevated temperature by rheology and SAXS, respectively. For PI-b-PFMMA with total molecular weight 13400 g/mol a phase transition at 105 °C was identified leading to the segmental mixing at T > 105 °C and microphase separation at T < 105 °C. The microphase separated morphology acquired hexahonally packed cylinder (HEX) microstructure in bulk. The explanation of the ordered HEX morphology was derived from a quantification of the thermodynamic immiscibility between PI and PFMMA segments via random phase approximation theory yielding generally accepted dependency of the Flory-Huggins interaction parameter (χ) on temperature.

Helical wrapping of diblock copolymers on nanocylinder

Abstract The development of the helical structure of diblock copolymers in solutions or melts is a challenging task although helices can be readily formed in a confined environment such as nanopore. In this study, dissipative particle dynamic simulations are performed to explore helical supramolecular structures self-assembled from diblock copolymers induced by nanocylinder. At low polymer concentrations, helical ellipsoids are formed on the nanocylinder and they remain stable after the nanocylinder is removed. As the concentration increases, three types of cylindrical morphologies appear: single-single helix, double-double helix, or segmented structures. The influences of block lengths and block-nanocylinder interaction on suprastructures are shown in the morphological phase diagram. When the nanocylinder is bounded by two planes, a helical funnel can emerge. In the presence of a ring-like nanoparticle, a helical toroid can arise. Our simulation results provide a new strategy for the fabrication of various helical assemblies of diblock copolymers in solutions.

Thermal Control of Confined Crystallization within P3EHT Block Copolymer Microdomains

The local, nanoscale organization of crystallites in conjugated polymers is often critical to determining the charge transport properties of the system. Block copolymer geometries, which offer controlled nanostructures with tethering of chains at interfaces, are an ideal platform to study the local organization of conjugated polymer crystallites. The model conjugated polymer poly(3-(2′-ethyl)hexylthiophene) (P3EHT) features a depressed melting temperature relative to the widely studied poly(3-hexylthiophene) (P3HT), which allows it to robustly form microphase-separated domains that confine the subsequent P3EHT crystallites. Importantly, P3EHT crystallization in confinement is coupled to a rubbery second block via interfacial tethering, mechanical properties, and chain stretching. Here, the impact of thermal processing on the diblock copolymer structure is examined to elucidate the key driving forces controlling the final coupled diblock copolymer and crystalline structures. Surprisingly, the diblock copol...

Realizing the Potential of Micro-Phase Separated Block Copolymer Electrolytes: Ion Domain Connectivity Plays a Prominent Role in Ion Conduction

Single ion conducting polymer electrolyte membranes (PEMs) are found at the heart of many electrochemical devices (e.g., fuel cells, flow batteries, electrolyzers, electrodialysis, etc.).(1) The key requirements for such materials include high ionic conductivity, electron insulation, mechanical resilience, selectivity (i.e., high transference #), and chemical, thermal, and mechanical stability.(2, 3) Ionic conductivity is particularly important because it strongly influences the ohmic overpotential in the said electrochemical devices affecting device efficiency.(1, 4) Block copolymer electrolytes represent an attractive set of PEM materials because their micro-phase architecture yields greater ion conduction over their random copolymer counterparts.(5-7) Furthermore, the block copolymer charateristic gives rise to a variety of morphological architectures, while engineering of the block copolymer’s self-assembly influences domain alignment.(8-12) However, there is lack of systematic studies correlating molecular level structural design to bulk material properties like ion transport. In this work, a model lamellae-forming diblock copolymer electrolyte system was manipulated to examine the extent of ion domain connectivity on ion conduction.(13, 14) Careful control of the model system’s volume fraction gave diblock copolymer structures with slightly rich electrolyte domains or slightly rich hydrophobic domains. The slightly rich electrolyte domains had greater contiguous area fraction while simultaneously demonstrating fewer terminal defects. Having a contiguous area fraction from 0.95 to 1.0 resulted in a 2x improvement in ionic conductivity over a non-micro-phase separated block copolymer electrolyte or a micro-phase separated block copolymer electrolyte with poor connectivity. Incremental adjustment in the extent of connectivity revealed an exponential growth curve for ion conductivity as a function of contiguous area fraction. Furthermore, the benefits that a micro-phase separated block copolymer electrolyte affords in terms of ion conductivity were not realized when the block copolymer electrolyte had poor connectivity. The results of this work have far reaching implication into the rationale design of PEM materials based upon block copolymer designs. This talk will emphasize the importance of maximizing ion domain connectivity while taking great strides to minimize terminal defects to boost ion transport in PEM materials. This talk will close with future directions on how molecular level engineering of block copolymer electrolytes offer the potential to reveal how other structural features (e.g., tortuosity(15), grain boundaries(5), and counterion condensation) alter ion transport in PEM materials(16, 17). 1. H. Strathmann et al., Ion-Exchange Membranes in the Chemical Process Industry. Industrial & Engineering Chemistry Research 52, 10364-10379 (2013). 2. H. Strathmann, Ion-Exchange Membrane Separation Processes, Volume 9. Membrane Science and Technology (Elsevier Science, Amsterdam, The Netherlands, 2004), vol. 9. 3. T. Sata, Ion Exchange Membranes: Preparation, Characterization, Modification and Application. (Royal Society of Chemistry, Cambridge, UK, 2004). 4. A. Z. Weber, J. Newman, Modeling Transport in Polymer-Electrolyte Fuel Cells. Chemical Reviews 104, 4679-4726 (2004). 5. Y. A. Elabd, M. A. Hickner, Block Copolymers for Fuel Cells. Macromolecules 44, 1-11 (2011). 6. N. Li, M. D. Guiver, Ion Transport by Nanochannels in Ion-Containing Aromatic Copolymers. Macromolecules 47, 2175-2198 (2014). 7. Y. Schneider et al., Ionic Conduction in Nanostructured Membranes Based on Polymerized Protic Ionic Liquids. Macromolecules 46, 1543-1548 (2013). 8. H. Hu, M. Gopinadhan, C. O. Osuji, Directed self-assembly of block copolymers: a tutorial review of strategies for enabling nanotechnology with soft matter. Soft Matter 10, 3867-3889 (2014). 9. M. Luo, T. H. Epps, III, Directed Block Copolymer Thin Film Self-Assembly: Emerging Trends in Nanopattern Fabrication. Macromolecules 46, 7567-7579 (2013). 10. S. Ji, L. Wan, C.-C. Liu, P. F. Nealey, Directed self-assembly of block copolymers on chemical patterns: A platform for nanofabrication. Progress in Polymer Science, 54-55, 76-127 (2016). 11. S.-J. Jeong et al., Directed self-assembly of block copolymers for next generation nanolithography. Materials Today 16, 468-476 (2013). 12. M. P. Stoykovich, P. F. Nealey, Block copolymers and conventional lithography. Materials Today 9, 20-29 (2006). 13. I. P. Campbell, G. J. Lau, J. L. Feaver, M. P. Stoykovich, Network Connectivity and Long-Range Continuity of Lamellar Morphologies in Block Copolymer Thin Films. Macromolecules 45, 1587-1594 (2012). 14. C. G. Arges, Y. Kambe, H. S. Suh, L. E. Ocola, P. F. Nealey, Perpendicularly Aligned, Anion Conducting Nanochannels in Block Copolymer Electrolyte Films. Chemistry of Materials 28, 1377-1389 (2016). 15. X. Feng et al., Scalable Fabrication of Polymer Membranes with Vertically Aligned 1 nm Pores by Magnetic Field Directed Self-Assembly. ACS Nano 8, 11977-11986 (2014). 16. K. M. Beers, D. T. Hallinan, X. Wang, J. A. Pople, N. P. Balsara, Counterion Condensation in Nafion. Macromolecules 44, 8866-8870 (2011). 17. K. M. Beers, N. P. Balsara, Design of Cluster-free Polymer Electrolyte Membranes and Implications on Proton Conductivity. ACS Macro Letters 1, 1155-1160 (2012). Figure 1

Capillary pore membranes with grafted diblock copolymers showing reversibly changing ultrafiltration properties with independent response to ions and temperature

Track-etched polyethylene terephthalate membranes with a pore size of 110nm have been modified by a grafted diblock copolymer structure in order to obtain dual-responsive ultrafiltration membranes. The temperature-responsive poly-N-isopropylacrylamide (PNIPAAm) and the ion-responsive poly-N,N-dimethyl-N-methacryloyloxyethyl-N-(3-sulfopropyl) ammonium betaine (PSPE) were grafted from the pore walls by sequential surface-initiated atom transfer radical polymerization. To achieve a well controlled pore functionalization, the polymerization rate had been adjusted to a very slow chain growth. A successful grafting of PSPE as first block and of PNIPAAm as second block could be demonstrated. To study the temperature and ion responsivity, hydraulic permeability and dextran diffusion experiments at 25°C and 40°C with different salt solutions had been carried out. It could be shown that such membranes can change their barrier pore size from a more open to a more closed state in dependency of temperature as well as kind of ions and their concentration in the feed. The grafted layer thickness showed a particularly strong increase in the presence of KClO4. Like expected for a well defined polymer brush, an expanded or collapsed state for each of the individual blocks could be obtained. In presence of KClO4 at 25°C both blocks are expanded and the pores are in a more closed state. If one of these stimuli is changed, for example when temperature is increased to 40°C or ions are removed, the block copolymer brushes collapse partially what leads to more open pores. However, if both stimuli are applied together, i.e. if temperature is 40°C and no ions are in solution, diblock copolymers collapse fully what leads to fully opened pores. It had also been demonstrated that this dual responsivity and the magnitude of the effects depend very strongly on the absolute degree of grafting and the ratio between the two different responsive polymer blocks. Furthermore, the ability of changing effective membrane barrier pore size by ions and temperature has been investigated in more detail by dextran diffusion experiments, and very pronounced and reversible changes of molecular sieving curve and molecular weight cut-off could be obtained.

Self-assembly of diblock copolymer confined in an array-structure space.

The combination of top-down and bottom-up technologies is an effective method to create the novel nanostructures with long range order in the field of advanced materials manufacture. In this work, we employed a polymeric self-consistent field theory to investigate the pattern formation of diblock copolymer in a 2D confinement system designed by filling pillar arrays with various 2D shapes such as squares, rectangles, and triangles. Our simulation shows that in such confinement system, the microphase structure of diblock copolymer strongly depends on the pitch, shape, size, and rotation of the pillar as well as the surface field of confinement. The array structures can not only induce the formation of new phase patterns but also control the location and orientation of pattern structures. Finally, several methods to tune the commensuration and frustration of array-structure confinement are proposed and examined.

Study of the stability of long-range-ordered lamellar structures for directed self-assembly lithography, performed using dissipative particle dynamics

We performed dissipative particle dynamics (DPD) simulations to obtain long-range-ordered lamellar structures for directed self-assembly lithography. The self-assembled structure of diblock copolymers (DBCs) depends on the length of the different blocks and the difference in their solubility parameters. In the DPD simulations, the DBCs were formed from coarse-grained particles, and the difference between the solubility parameters was represented by a repulsion parameter. We examined the phase separation morphology of the DBCs, which were confined using a trench model system. The repulsion parameter for the assembly of the lamellar structures from the DBC particles was chosen from six types of parameters. The orientation of the lamellar structure was controlled by the repulsion parameter that described the repulsion between the particles and the wall of the system. We changed the width of the trench, and examined the probability for the formation of the lamellar structure. The lamellar structure could not be obtained by increasing the width. To increase the probability, we placed a ridge at the centre of the bottom wall. It was found that the presence of the ridge increased the probability for the formation of the long-range-ordered lamellar structures.

A Modular Approach Towards Fluorescent pH and Ascorbic Acid Probes Based on Ring‐Opening Metathesis Polymerization

Copolymerization represents a modular synthetic strategy toward optochemical sensors by disassembling small molecule probes and recombining them to screen various fluorophore‐quencher combinations, instead of synthesizing individual sensor molecules. To demonstrate this, a polymerizable, fluorescent 1,6,7,12‐tetrachloroperylene‐3,4:9,10‐bis(dicarboximide) derivative with a norbornene ester side chain is prepared and copolymerized with a tertiary‐amine‐bearing monomer, as well as an oligo‐glycol‐bearing monomer, via ring‐opening metathesis polymerization (ROMP). In this manner, water‐soluble optical pH sensor polymers (with apparent pka values of 6.4–7) are obtained. The effect of the macromolecular architecture on the sensing performance is evaluated, whereby a diblock copolymer structure made of an oligoglycol segment and a segment containing the secondary amine and the fluorescent moiety is identified as being most favorable for pH sensing. Similarly, profluorescent polymers are obtained by employing nitroxides instead of secondary amines, which allows detection of ascorbic acid (with a detection limit of 0.1 × 10−3m) in water. image

Nano tools for macro problems: multiscale molecular modeling of nanostructured polymer systems

A current challenge of physical, chemical, and engineering sciences is to develop theoretical tools for predicting structure and properties of complex materials from the knowledge of a few input parameters. In this work, we present a general multiscale molecular simulation protocol for predicting morphologies and properties of nanostructured polymer systems and we apply it to three examples of industrial relevance. The first example is of general importance for the polymer industry and is related to the enhancement of mechanical and barrier properties, if a nanofiller is dispersed into a polymer matrix: the role of multiscale modeling for the development of the material in the stage of screening, the best design is evidenced. The second example, important for the optoelectronic industry, is related to the prediction of the dispersion of gold nanoparticles into a diblock copolymer system forming different nanostructures (lamellae, cylinders, …). In this case, it is relevant to understand how it is possible to influence the self-assembly of the nanoparticles in different regions of the diblock copolymer structure. The third example is of interest to automotive and polymer industries and involves inorganic nanoparticles grafted with organic side chains. The assembly is dispersed in a polymeric matrix and it is interesting to predict the effect of the chain length and grafting density on the nanostructure.