Single Homopolymer Research Articles

Poly(N-acryloyl glycinamide) conducted “thermo-schizophrenic” graphene oxide membrane

A poly(N-acryloyl glycinamide) (PNAGA) conducted smart graphene oxide (GO) membrane was fabricated, which exhibits a unique “thermo-schizophrenic” phenomenon. The combination of supramolecular interactions at different temperatures and confined nano-channels was considered to arouse such new properties. The aggregation of PNAGA fragments, homogeneously polymer distribution, and chain stretching based on supramolecular interactions at different temperatures, cause the “thermo-schizophrenic” feature. The limited size of the nano-channel constructed by GO also contributed to this newfangled adjustable superfluid phenomenon. Overall, this work provides a substantial and definitive complementarity to the unique application of PNAGA at different temperatures. It induces a way to prove the significance and specialty of the confined spacing in designing the 2D-nanofiltration membrane. This strategy also gives valuable guidance for designing smarter materials using a single homopolymer.

Machine learning of an implicit solvent for dynamic Monte Carlo simulations.

The Bond Fluctuation Model (BFM) is a highly efficient and versatile method for simulating polymers, membranes, and soft matter. Due to its coarse-grained nature, the BFM is employed to understand the universal properties of polymers. Solvent effects are often mediated by explicit solvent particles, while implicit solvent models have had limited use as they may lead to frozen states and, thus, ergodicity-related problems. In simulation setups, such as coagulated multiple homopolymers chains, explicit solvent models are computationally expensive because the region of interest can be localized in a small space compared to the dimension of the periodic box. We introduce an implicit solvent model based on an artificial neural network (NN) that was trained with BFM simulation data for single homopolymers in an explicit solvent. We demonstrate that NN-based simulations that take into account only the information of the local environment of monomers reproduce the expected universal macroscopic properties of the polymer under varying solvent conditions. The homopolymer chains simulated using the NN reproduce the coil-globule transition, the static and dynamic bond autocorrelation, and the mean square displacement of chain monomers. We show that the learned parameters from a single chain system can be transferred to a system containing multiple homopolymers, indicating that the learned parameters are transferable to considerably different systems.

Effect of bending stiffness on the polymer adsorption onto a heterogeneous stripe-patterned surface

Adsorption of a single homopolymer chain with bending stiffness onto a heterogeneous regular stripe-patterned surface consisting of adsorbing and non-adsorbing stripes is studied theoretically in the framework of the lattice model and the generating functions approach. The stiffness is introduced by assigning a statistical weight to a trans-isomer (a straight segment) with respect to a gauche-isomer (a kink). The temperature is taken as the main control parameter since it affects both the strength of the monomer units’ attraction to the adsorbing stripes and the chain stiffness. It is shown that the adsorption transition temperature is a non-monotonic function on the bending energy having a minimum. The position of this minimum depends on the stripes’ width and only slightly deviates from zero bending energy. Temperature dependences of the main conformational and thermodynamic characteristics of the adsorbed chain are obtained. It is demonstrated that in most of the studied cases the adsorption is accompanied by the chain localization on a single adsorbing unit stripe and the chain stiffness enhances this effect.

High Spatial Resolution of Ultrathin Covalent Organic Framework Nanopores for Single-Molecule DNA Sensing

Ultrathin nanosheets of two-dimensional covalent organic frameworks covered a quartz nanopipette and then acted as a nanopore device for single-molecule DNA sensing. Our results showed that a single DNA homopolymer as short as 6 bases could be detected. The dwell times of 30-mer DNA homopolymers were obviously longer than the times of 10- or 6-mer ones. For different bases, poly(dA)6 showed the slowest transport speed (∼595 μs/base) compared with cytosine (∼355 μs/base) in poly(dC)6 and thymine (∼220 μs/base) in poly(dT)6. Such translocation speeds are the slowest ever reported in two-dimensional material-based nanopores. Poly(dA)6 also showed the biggest current blockade (94.74 pA) compared with poly(dC)6 (79.54 pA) and poly(dT)6 (71.41 pA). However, the present difference in blockade current was not big enough to distinguish the four DNA bases. Our study exhibits the shortest single DNA molecules that can be detected by COF nanopores at the present stage and lights the way for DNA sequencing based on solid-state nanopores.

Orientation- and cosolvent-induced self-assembly of amphiphilic homopolymers in selective solvents

Self-assembly of single amphiphilic homopolymer in solvents with inverse selectivities, characterized by symmetric affinity and disgust to backbone and side groups, and their binary mixtures are studied by means of computer simulations and analytical theory, depending on composition and miscibility of components. In each of these two solvents separately, the polymer chain forms either multidomain or beads-on-a-string structures. Morphological contrast comes from the distinction in orientational mobility of side groups. In the backbone-selective solvent, the enhancing of orientational mobility of pendant groups due to merging of soluble shells of beads gives rise to a new type of attraction - orientation-induced attraction, which leads to close packing of intrachain micelles into the multidomain structure. In binary solvent the amphiphilic homopolymer manifests cosolvency behavior. At strong incompatibility of solvents variation of composition toward the equal concentrations of the solvents provokes series of morphological transitions, accompanied by gradual uptake of minor component of the solvent mixture into the assembly.

On the adsorption of a polymer chain with positive or negative bending stiffness onto a planar surface

Adsorption of a single homopolymer chain with bending stiffness on a homogeneous planar surface is studied theoretically in the framework of the lattice model and the generating functions approach. The stiffness is introduced by assigning a statistical weight to a trans-isomer (a straight segment) with respect to a gauche-isomer (a kink). This statistical weight is related to the bending energy εbend associated with a kink: k=exp(εbend∕kBT) and depends on the temperature but one can also treat k as a temperature-independent parameter. Both positive and negative values of the bending energy corresponding to stiff (εbend>0, k>1, positive stiffness) and “quasi-zigzag” (εbend<0, 0<k<1, negative stiffness) chains are considered. The dependence of the adsorption transition temperature on εbend and k is non-monotonic and has a minimum for flexible chains at εbend=0 and k=1. At the same time, at moderate and strong adsorption, the fraction of adsorbed units is a strictly increasing function of the bending energy or the stiffness parameter. Adsorption is accompanied by the straightening of the chain in the case of positive εbend and its “zigzaging” in the case of negative εbend. In contrast, when k is temperature independent, a decrease in temperature leads to the increase in the fraction trans-isomers at any positive k. The temperature dependence of the specific heat can exhibit one or two maxima in addition to the jump in at the adsorption (second order) transition point.

A Computational Study on the LCST Phase Transition of a POEGMA Type Thermoresponsive Block Copolymer: Effect of Water Ordering and Individual Behavior of Blocks.

The atomistic origin underlying the lower critical solution temperature (LCST) behavior of thermoresponsive copolymers in water is still elusive. Here, we report all-atom molecular dynamics simulations of block copolymers of 2-(2-methoxyethoxy)ethyl methacrylate (MEO2MA) and oligo(ethylene glycol) methyl ether methacrylate (OEGMA300) in water at various block ratios and at temperatures below and above the LCST values of each homopolymer block. Our single chain simulations showed that hydration water molecules accumulate particularly near the side chain carbon atoms by forming ordered cage-like structures via extensive hydrogen bonding between them. These water cage formations surround the entire surface of PMEO2MA- b-POEGMA300 and enable the copolymer to remain in water below the LCST. As the temperature increases, each block exhibits a separate coil-to-globule transition above its own LCST. A detailed analysis of the interactions between polymer-water and water-water revealed that this phase transition is mainly driven by the reduced local water ordering by the disruption of the water cages when the temperature is increased above the LCST. We found that the transition occurs differently in the copolymer than the POEGMA homopolymers due to the interaction of the blocks, especially around the joint of the blocks. Accordingly, the phase transition of a block acts as an additional disruptive effect on the other block's water cage structure, which reduces the LCST values of PMEO2MA and POEGMA300 in the copolymer, compared to their individual single chain homopolymers.

Micro/Nano-structured Conducting Copolymer from Aniline with 3,4-Ethylenedioxythiophene and their Property

Novel conducting copolymers from aniline (AN) with 3,4-ethylenedioxythiophene (EDOT) with different micro/nano-structures were synthesized by chemical oxidation. The influences of [EDOT]/[AN] molar ratios on morphology, structure, electrical conductivity, and solubility of copolymers are systematically studied. It is found that the copolymer’s morphologies as well as electrical conductivity vary with the change of [EDOT]/[AN], and the extremum exists during the conductivity variation. From the SEM photograph, we can know that the copolymer has a uniform nanofiber structure at [EDOT]/[AN] = 1.5/1. It is shown in the infrared spectrum that the copolymer has both the macromolecular chain structure of PANI and PEDOT, indicating that the copolymerization effect of the two is very good. The UV absorption spectrum is non-monotonic with the change of [EDOT]/[AN] molar ratio, which also proves the copolymerization structure of EDOT and AN. Interestingly, the copolymers exhibit better solubility and partial crystallinity compare with each single homopolymer. Moreover, the copolymer presents good electrochromic properties with the reversible color change among blue, blue green, yellowish green, which combines the color variation range of PANI and PEDOT.

The folding pathways and thermodynamics of semiflexible polymers.

Inspired by the protein folding and DNA packing, we have systematically studied the thermodynamic and kinetic behaviors of single semiflexible homopolymers by Langevin dynamics simulations. In line with experiments, a rich variety of folding products, such as rod-like bundles, hairpins, toroids, and a mixture of them, are observed in the complete diagram of states. Moreover, knotted structures with a significant population are found in a certain range of bending stiffness in thermal equilibrium. As the solvent quality becomes poorer, the population of the intermediate occurring in the folding process increases, which leads to a severe chevron rollover for the folding arm. However, the population of the intermediates in the unfolding process is very low, insufficient to induce unfolding arm rollover. The total types of folding pathways from the coil state to the toroidal state for a semiflexible polymer chain remain unchanged by varying the solvent quality or temperature, whereas the kinetic partitioning into different folding events can be tuned significantly. In the process of knotting, three types of mechanisms, namely, plugging, slipknotting, and sliding, are discovered. Along the folding evolution, a semiflexible homopolymer chain can knot at any stage of folding upon leaving the extended coil state, and the probability to find a knot increases with chain compactness. In addition, we find rich types of knotted topologies during the folding of a semiflexible homopolymer chain. This study should be helpful in gaining insight into the general principles of biopolymer folding.

Cascade post-polymerization modification of single pentafluorophenyl ester-bearing homopolymer as a facile route to redox-responsive nanogels

Poly(pentafluorophenyl methacrylate) (PPFPMA) was first subjected to post-polymerization modification with oligo(ethylene glycol) methyl ether amine (OEG-NH2) and yielded poly(pentafluorophenyl methacrylate)-co-poly(oligo(ethylene glycol methacrylamide)), PPFPMA-co-POEGMAM. These amphiphilic random copolymers can self-assemble into micellar nanoparticles in water having sizes less than 100nm. By tandemly reacting the pentafluorophenyl (PFP) groups in the copolymeric nanoparticles with a dithiol crosslinker, cystamine, redox-responsive nanogels can be formed. The last step of post functionalization with isopropylamine was introduced in order to remove the remaining PFP groups in the nanogels. Stepwise post functionalization can be monitored by FTIR and 19F NMR spectroscopy. Release of a model hydrophobic drug, nile red (NR) from the nanogels, simultaneously encapsulated during micelles formation, can be accelerated in the presence of glutathione (GSH) especially at 37°C. Results from cytocompatibility evaluation suggested that these developed redox-responsive nanogels strongly possessed a potential for applications in controlled delivery.

A Tetragonal Phase Self-Organized from Unimolecular Spheres Assembled from a Substituted Poly(2-oxazoline)

Synthesis and living cationic ring-opening polymerization of a 2-oxazoline containing self-assembling minidendrons with hexadecyl groups are reported. Structural analysis using X-ray diffraction, molecular modeling, and reconstructed electron density maps revealed multiple self-organized periodic arrays, including columnar hexagonal P6mm, cubic Pm3n, and tetragonal P42/mnm phases, which have not been observed before in a single homopolymer. The degree of polymerization (DP) of the poly(2-oxazoline) programs the sequence of these periodic arrays. The cubic Pm3n phase was observed for DP = 5 whereas the tetragonal P42/mnm for 10 ≤ DP ≤ 50. For DP ≥ 75, only a columnar hexagonal P6mm phase was accessible because the polymer chains are too long to form a single supramolecular sphere. This sequence was rationalized by the columnar character of supramolecular spheres to provide the richest diversity of structures assembled from a single polymer and an unprecedented example of a tetragonal phase organized from...

Binary Mixed Homopolymer Brushes Tethered to Cellulose Nanocrystals: A Step Towards Compatibilized Polyester Blends.

This article reports on the successful preparation and characterization of cellulose nanocrystals (CNCs) surface-modified with polylactide (PLA) and poly(butylene succinate) (PBS) binary mixed homopolymer brushes. Their synthesis was designed as a three-step procedure combining polyester synthesis and surface-modification of CNCs with simultaneous polyester grafting via a heterogeneous copper(I)-catalyzed azide-alkyne cycloaddition reaction. For comparison, single homopolymer brushes tethered to CNCs (PLLA-g-CNC and PBSBDEMPAM-g-CNC) were obtained applying the same procedure. The hairy nanoparticles were characterized in terms of chemical composition and thermal properties. Spectroscopic analyses suggested "rippled" microphase separation of both immiscible homopolyesters in the mixed brushes, while others showed impeded homopolyester crystallization after surface-grafting. A synergistic relationship between the polyesters and CNCs was also suggested, i.e., the polyester grafting increases the CNC thermal resistance, while CNC presence imparts char formation. The as-obtained binary homopolymer brushes tethered to nanoparticles makes these surface-modified cellulosic nanomaterials attractive as compatibilization/reinforcement agents for PLA/PBS blends.

Self-assembly diblock copolymers confined between mixed brush-grafted surfaces

The confined environment plays a very important role in the phase separation of copolymers, which can change bulk phase behaviors of copolymers. The different confinement conditions can induce the formations of various interesting and novel morphologies, which can be used in a variety of nanotechnology applications such as high-density medium storage, nanolithography and photonic crystals. The grafting of polymers to confined surfaces is an efficient means for tailoring surface properties. In this work, we investigate the effect on architecture of the AB diblock copolymer confined between mixed brush-grafted surfaces by using self-consistent field theory. The brush contains two types of homopolymers. We study the effects of the fraction of A block, grafted period and the volume fraction of the polymer brush, the distance between two surfaces and the interaction strength between two blocks on the morphology. 1) With the increase of the fraction of A block (fA), the phase morphology changes from the A-block hexagonal cylinder to the parallel lamellae, to the curving lamellae, and then to the B-block hexagonal cylinder. The period of hexagonal cylinder and curving lamellae is equal to the grafted period of the polymer brush due to the influence of the polymer brush. 2) The grafted period of polymer brush is a very important factor for the morphology of diblock copolymer. When fA=0.3, we change the grafted period of the polymer brush. We obtain the phase transition from the hexagonal cylinder to the alternating phase of tetragonal and hexagonal cylinder, then to the alternating phase of tetragonal and octagonal cylinder. When fA=0.4, the structure changes from the hexagonal cylinder to the order phase of the waving lamellae and cylinder with the increase of the grafted period of the polymer brush. Compared with the single homopolymer brush system, the mixed brush enlarges the range of ordered phase and reduces the range of disordered phase. Block copolymers are prone to forming cylinder in mixed brush system and tending to form lamellae in single homopolymer brush system. 3) When fA=0.3, we obtain the phase transition from the hexagonal cylinder to the one-layered cylinder phase by increasing the volume fraction of the polymer brush. This transition is different from that of the single homopolymer brush system. Interestingly, when fA=0.45, the structure of AB block copolymer changes from the parallel lamellae to the perpendicular lamellae with the increase of the volume fraction of the polymer brush. The entropic energy plays an important role in this transition process. Similarly, we also observe the phase transition from the parallel lamellae to the perpendicular lamellae by decrease the distance between two surfaces. 4) We construct the phase diagram for a range of the fraction of A block and the interaction strength. The results provide an effective approach to obtaining the desired microstructures for fabricating nanomaterials.

Phase diagram and the pseudogap state in a linear chiral homopolymer model.

The phase structure of a single self-interacting homopolymer chain is investigated in terms of a universal theoretical model, designed to describe the chain in the infrared limit of slow spatial variations. The effects of chirality are studied and compared with the influence of a short-range attractive interaction between monomers, at various ambient temperature values. In the high-temperature limit the homopolymer chain is in the self-avoiding random walk phase. At very low temperatures two different phases are possible: When short-range attractive interactions dominate over chirality, the chain collapses into a space-filling conformation. But when the attractive interactions weaken, there is a low-temperature unfolding transition and the chain becomes like a straight rod. Between the high- and low-temperature limits, several intermediate states are observed, including the θ regime and pseudogap state, which is a novel form of phase state in the context of polymer chains. Applications to polymers and proteins, in particular collagen, are suggested.

Interaction of meso-tetrakis(N-methylpyridinyl)porphyrin with single strand DNAs – poly(dA), poly(dT), poly(dG) and poly(dC): A photophysical study

Interaction between meso-tetrakis(N-methylpyridinyl)porphyrin (TMPyP) and single strand DNA homopolymers, (dA)40, (dT)40, (dG)40 and (dC)40, has been investigated using absorption, fluorescence and circular dichroism (CD) measurements. Fluorescence intensity of TMPyP is quenched in the presence of (dG)40 due to photo-induced electron transfer from dG to the excited TMPyP dye. Changes in the CD spectra of the polynucleotides in the presence of TMPyP are found to be quite different and depend on the nature of the nucleotide bases, whether purine or pyrimidine. Excitonic induced CD spectra is observed for TMPyP in the presence of pyrimidine homopolymers while negative induced CD is observed in the presence of purine homopolymers. Based on photophysical studies and CD spectra, we propose multiple binding modes of TMPyP with polynucleotides. TMPyP can bind to oligonucleotides both in monomer form as well as in the form of short stretches of stacked aggregates along the oligonucleotide backbone. Interaction between meso-tetrakis(N-methylpyridinyl)porphyrin (TMPyP) and single strand DNA homopolymers, poly(dA)40, poly(dT)40, poly(dG)40 and poly(dC)40, has been investigated. Based on photophysical studies, we propose that TMPyP binds to the oligonucleotides, both in monomer form as well as in the form of short stretches of stacked aggregates along the oligonucleotide backbone.

Thermodynamic and conformational insights into the phase transition of a single flexible homopolymer chain using replica exchange Monte Carlo method.

The phase transition of a single flexible homopolymer chain in the limit condition of dilute solution is systematically investigated using a coarse-grained model. Replica exchange Monte Carlo method is used to enhance the performance of the conformation space exploration, and thus detailed investigation of phase behavior of the system can be provided. With the designed potentials, the coil-globule transition and the liquid-solid-like transition are identified, and the transition temperatures are measured with the conformational and thermodynamic analyses. Additionally, by extrapolating the coil-globule transition temperature, T Θ , and the liquid-solid-like transition temperature T(L → S) to the thermodynamic limit, N → ∞, we found no "tri-critical" point in the current model.

Single Polymer Studies of Hydrophobic Hydration

Hydrophobic interactions guide protein folding, multidomain protein assembly, receptor-ligand binding, membrane formation, and cellular transportation. On the macroscale, hydrophobic interactions consist of the aggregation of "oil-like" objects in water by minimizing the interfacial energy. However, studies of the hydration behavior of small hydrophobic molecules have shown that the microscopic (~1 nm) hydration mechanism differs fundamentally from its macroscopic counterpart. Theoretical studies over the last two decades have pointed to an intricate dependence of molecular hydration mechanisms on the length scale. The microscopic-to-macroscopic crossover length scale is critically important to hydrophobic interactions in polymers, proteins, and other macromolecules. Accurate experimental determination of hydration mechanisms and interaction strengths directly influence our understanding of protein folding. In this Account, we discuss our recent measurements of the hydration energies of single hydrophobic homopolymers as they unfold. We describe in detail our single molecule force spectroscopy technique, the interpretation of the single polymer force curve, and how it relates to the hydration free energy of a hydrophobic polymer. Specifically, we show how temperature, side-chain sizes and solvent conditions, affect the driving force of hydrophobic collapse. The experiments reveal that the size of the nonpolar polymer side-chains changes the thermal signatures of hydration. The sizes of the polymer side-chains bridge the length scale where theories had predicted a transition between entropically driven microscopic hydration and enthalpically driven macroscopic hydrophobic hydration. Our experimental results revealed a crossover length scale of approximately 1 nm, similar to the results from recent theoretical studies. Experiments that probe solvent dependency show that the microscopic polymer hydration is correlated with macroscopic interfacial tension. Consistent with theoretical predictions, the solvent conditions affect the microscopic and macroscopic hydrophobic strengths in similar ways. Although the extended polymers and proteins span hundreds of nanometers, the experiments show that their hydration behavior is determined by the size of a single hydrophobic monomer. As the hydrophobic particle size decreases from the macroscopic to the microscopic regime, the scaling relationship changes from a dependence on interfacial area to a dependence on volume. Therefore, under these conditions, the driving force for the aggregation of hydrophobic molecules is reduced, which has significant implications for the strength of hydrophobic interactions in molecular systems, particularly in protein folding.

Microstructure of Copolymers Formed by the Reagentless, Mechanochemical Remodeling of Homopolymers via Pulsed Ultrasound.

The high shear forces generated during the pulsed ultrasound of dilute polymer solutions lead to large tensile forces that are focused near the center of the polymer chain, but quantitative experimental evidence regarding the force distribution is rare. Here, pulsed ultrasound of quantitatively geminal-dihalocyclopropanated (gDHC) polybutadiene provides insights into the distribution. Pulsed ultrasound leads to the mechanochemical ring-opening of the gDHC mechanophore to a 2,3-dihaloalkene. The alkene product is then degraded through ozonolysis to leave behind only those stretches of the polymer that have not experienced large enough forces to be activated. Microstructural and molecular weight analysis reveals that the activated and unactivated regions of the polymer are continuous, indicating a smooth and monotonic force distribution from the midchain peak toward the polymer ends. When coupled to chain scission, the net process constitutes the rapid, specific, and reagentless conversion of a single homopolymer into block copolymers. Despite their compositional polydispersity, the sonicated polymers assemble into ordered lamellar phases that are characterized by small-angle X-ray scattering.

Isopeptide Bonds Block the Mechanical Extension of Pili in Pathogenic Streptococcus pyogenes

In the early stages of an infection, pathogenic bacteria use long fibrous structures known as pili as adhesive anchors for attachment to the host cells. These structures also play key roles in colony and biofilm formation. In all those processes, pili must withstand large mechanical forces. The pili of the nasty gram-positive human pathogen Streptococcus pyogenes are assembled as single, micrometer long tandem modular proteins of covalently linked repeats of pilin proteins. Here we use single molecule force spectroscopy techniques to study the mechanical properties of the major pilin Spy0128. In our studies, we engineer polyproteins containing repeats of Spy0128 flanked by the well characterized I27 protein which provides an unambiguous mechanical fingerprint. We find that Spy0128 is an inextensible protein, even when pulled at forces of up to 800 pN. We also found that this remarkable mechanical resilience, unique among the modular proteins studied to date, results from the strategically located intramolecular isopeptide bonds recently identified in the x-ray structure of Spy0128. Removal of the isopeptide bonds by mutagenesis readily allowed Spy0128 domains to unfold and extend, albeit at relatively high forces of 172 pN (N-terminal domain) or 250 pN (C-terminal domain). Our results show that in contrast to the elastic roles played by large tandem modular proteins such as titin and fibronectin, the giant pili of S. pyogenes evolved to abrogate mechanical extensibility, a property that may be crucial in the pathogenesis of this most virulent bacterium and, therefore, become the target of new therapeutic approaches against its infections.

Schizophrenic Behavior of a Thermoresponsive Double Hydrophilic Diblock Copolymer at the Air−Water Interface

The thermoresponsive behavior of the rhodamine B end-labeled double hydrophilic block copolymer (DHBC) poly(N,N-dimethylacrylamide)-b-poly(N,N-diethylacrylamide) (RhB-PDMA(207)-b-PDEA(177)) and the 1:1 segmental mixture of PDEA and rhodamine B end-labeled PDMA homopolymers was studied over the range of 10-40 degrees C at the air-water interface. The increase in collapse surface pressure (second plateau regime) of the DHBC with temperature confirms the thermoresponsiveness of PDEA at the interface. The sum of the pi-A isotherms of the two single homopolymers weighted by composition closely follows the pi-A isotherm of the DHBC, suggesting that the behavior of each block of the DHBC is not influenced by the presence of the other block. Langmuir-Blodgett monolayers of DHBC deposited on glass substrates were analyzed by laser scanning confocal fluorescence microscopy (LSCFM), showing schizophrenic behavior: at low temperature, the RhB-PDMA block dominates the inside of bright (core) microdomains, switching to the outside (shell) at temperatures above the lower critical solution temperature (LCST) of PDEA. This core-shell inversion triggered by the temperature increase was not detected in the homopolymer mixture. The present results suggest that both the covalent bond between the two blocks of the DHBC and the tendency of rhodamine B to aggregate play a role in the formation of the bright cores at low temperature whereas PDEA thermoaggregation is responsible for the formation of the dark cores above the LCST of PDEA.