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A new methodology to assess ion diffusion in side-chain modified AEMs reveals separate roles for functionality and side-chain length: the former determines hydrophilic pathway morphology and the latter regulates anion diffusion rate in the channels.

The development of simulation methods to study the structure and dynamics of a macroscopically sized piece of polymer material is important as such methods can elucidate structure-property relationships. Several methods have been reported to construct initial structures for homo- and co-polymers; however, most of them are only useful for short linear polymers since one needs to pack and equilibrate the far-from-equilibrium initial structures, which is a tedious task for long or hyperbranched polymers and unfeasible for polymer networks. In this method article, we present PolySMart, i.e., an open-source python package, which can effectively produce fully equilibrated homo- and hetero-polymer melts and solutions with no limitation on the polymer topology and size, at a coarse-grained resolution and through a bottom-up approach. This python package is also capable of exploring the polymerization kinetics through its reactive scheme in realistic conditions so that it can model the multiple co-occurring polymerization reactions (with different reaction rates) as well as consecutive polymerizations under stoichiometric and non-stoichiometric conditions. Thus, the equilibrated polymer models are generated through correct polymerization kinetics. A benchmark and verification of the performance of the program for several realistic cases, i.e., for homo-polymers, co-polymers, and crosslinked networks, is given. We further discuss the capability of the program to contribute to the discovery and design of new polymer materials.

The risk of clot formation in blood-contacting devices is a significant concern. Therefore, development of biomaterials with improved hemocompatibility is a clinical need. Altering surface properti...

Smart coatings have aroused a growing interest because of the performance of predefined surface functions upon reacting to external stimuli. Among them, responsive polymer coatings to water, which often benefit from the presence of a mobile hydrophilic material, are of great interest. Polyurethanes (PUs) are versatile materials with respect to the structure-property relationship. Therefore, the incorporation of hydrophilic segments in PUs is a rational way to produce water-sensitive smart coatings; however, having a considerable amount of hydrophilic material deteriorates the physical properties because of a large amount of water uptake. In this study, we have analyzed previously synthesized smart PUs, based on hydrophobic polycarbonate (PC) and hydrophilic polyethylene glycol (PEG) soft segments, in which only a limited amount of PEG is used. These coatings maintain, more or less, zero water contact angle, whereas the water uptake remains below 15 wt %. The combination of experimental analysis and coarse-grained molecular dynamics (CG MD) simulations reveals that PEG segments migrate to the coating/water interface and partially cover the surface, whereas the hydrophobic nature of the PC keeps the bulk of the coating intact when the coating is covered with water. Moreover, our CG MD simulations and experimental analysis suggest a reversible phase arrangement under wet/dry cycles on molecular and macroscopic scales.

The rational design of perfluorinated amphiphiles to control the supramolecular aggregation in an aqueous medium is still a key challenge for the engineering of supramolecular architectures. Here, the synthesis and physical properties of six novel non-ionic amphiphiles are presented. The effect of mixed alkylated and perfluorinated segments in a single amphiphile is also studied and compared with only alkylated and perfluorinated units. To explore their morphological behavior in an aqueous medium, dynamic light scattering (DLS) and cryogenic transmission electron microscopy/electron microscopy (cryo-TEM/EM) measurements are used. The assembly mechanisms with theoretical investigations are further confirmed, using the Martini model to perform large-scale coarse-grained molecular dynamics simulations. These novel synthesized amphiphiles offer a greater and more systematic understanding of how perfluorinated systems assemble in an aqueous medium and suggest new directions for rational designing of new amphiphilic systems and interpreting their assembly process.

Simulation studies of step-growth polymerization, e.g., polymerization of polyurethane systems, hold great promise due to having complete control over the reaction conditions and being able to perform an in-depth analysis of network structures. In this work, we developed a (completely automated) simulation method based on a coarse-grained (CG) methodology, i.e., the MARTINI model, to study the cross-linking reaction of a diol, a tri-isocyanate molecule and one-hydroxyl functional molecule to form a polyurethane network without and with dangling chains. This method is capable of simulating the cross-linking reactions not only up to very high conversions, but also under rather complicated reaction conditions, i.e., a non-stoichiometric ratio of the reactants, solvent evaporation and multi-step addition of the reactants. We introduced a novel network analysis, similar to size-exclusion chromatography based on graph theory, to study the growth of the network during the polymerization process. By combining the reaction simulations with these analysis methods, a set of correlations between the reaction conditions, reaction mechanisms and final network structure and properties is revealed. For instance, a two-step addition of materials for the reaction, i.e., first the dangling chain to the tri-isocyanate and then the diol, leads to the highest integrated network structure. We observed that different reaction conditions lead to different glass transition temperatures (Tg) of the network due to the distinct differences in the final network structures obtained. For example, by addition of dangling chains to the network, the Tg decreases as compared to the network without dangling chains, as also is commonly observed experimentally.

Various physical and chemical surface parameters, e.g., surface roughness and surface chemistry, contribute to anti-soiling (AS) properties. Nevertheless, the effect of surface chemistry has not been distinctly elucidated yet. In this study, a set of mechanically stable and durable hydrophobic AS coatings with controlled surface chemistry were synthesized, while surface roughness was kept below 1 nm. Fluoroalkylsilane (FAS), alkylsilane (AL), and tetraethyl orthosilicate (TEOS) were employed for synthesis. Surface chemistry and surface roughness were quantified by XPS and AFM. A soiling lab simulator was designed to accelerate the soiling process. AS properties were quantified by UV–vis spectroscopy and optical microscopy. The surface free energy of coatings was estimated through (polar and apolar liquids) contact angle measurements (ranging from 16 to 30 mN/m), and a clear correlation was discovered between the AS properties and surface free energy. Moreover, mechanical properties and weathering resistance of the coatings were analyzed by nano-indentation and QUV accelerated weathering tester. While all coatings showed acceptable AS properties (transmission loss after dust deposition between 1/5 and 2/5 of uncoated glass) and excellent mechanical strength (above 27 GPa modulus and 2 GPa hardness), FAS-based coatings showed a significantly higher durability against weathering as compared to the AL-based ones. © 2022 Elsevier B.V.

The interplay of fluorination and structure of alkane self-assembled monolayers and how these affect hydrophobicity are explored via molecular dynamics simulations, contact angle goniometry, and surface-enhanced infrared absorption spectroscopy. Wetting coefficients are found to grow linearly in the monolayer density for both alkane and perfluoroalkane monolayers. The larger contact angles of monolayers of perfluorinated alkanes are shown to be primarily caused by their larger molecular volume, which leads to a larger nearest-neighbor grafting distance and smaller tilt angle. Increasing the Lennard-Jones force cutoff in simulations is found to increase hydrophilicity. Specifically, wetting coefficients scale like the inverse square of the cutoff, and when extrapolated to the infinite cutoff limit, they yield contact angles that compare favorably to experimental values. Nanoscale roughness is also found to reliably increase monolayer hydrophobicity, mostly via the reduction of the entropic part of the work of adhesion. Analysis of depletion lengths shows that droplets on nanorough surfaces partially penetrate the surface, intermediate between Wenzel and Cassie-Baxter states.

Polymer networks with hydrophilic dangling chains are ideal candidates for many submerged applications, e.g., protein non-adhesive coatings with non-fouling behavior. The dangling chains segregate from the polymer network towards the water and form a brush-like structure at the interface. Several factors such as the polymer network structure, dangling chain length, and water/dangling chain interaction may all affect the interfacial performance of the polymer. Therefore, we employed a Martini based coarse-grained (CG) molecular dynamics (MD) simulation to elucidate the influences of the abovementioned parameters on dangling chain interfacial segregation. We built up several polyurethane (PU) networks based on poly(tetra methylene glycol) (PTMG), as a macrodiol, and methoxy poly(ethylene glycol) (mPEG), as a dangling chain, with varying molecular weights. We found out that the macrodiol/dangling chain length ratio considerably smaller than one impedes the migration of dangling chains towards the water interface, while the dangling chain hydrophilicity and length determine the polymer interfacial layer density/thickness. Then, we artificially changed the dangling chain affinity to water from an intermediate to a very attractive water/dangling chain interaction. We justified that a brush-like structure forms in two consecutive steps: first, a longitudinal, and then a lateral migration of dangling chains in water. The latter step results in a uniform interfacial layer over the polymer interface that mainly occurs in the case of the attractive water/dangling chain interaction.

There is a common knowledge that the dynamic and structural behavior of polymer chains in the vicinity of nano-fillers is rather different from the bulk. Despite the extensive literature on this topic, this phenomenon is not yet fully understood. Apart from several experimental methods to study it, molecular simulations, in particular molecular dynamics (MD) methods, are good candidates for such study. In other words, MD simulation techniques give us a remarkable ability for mechanistic studies of dynamic and structural properties of polymer chains in nano-scales and they are proved to be highly reliable methods for estimating such properties. Therefore, in this study, we developed a time and spatially-resolved molecular dynamic method by which the structural and dynamic properties of two polymers, i.e., polypropylene (PP) and polyvinyl alcohol (PVA), are studied as a function of distance from graphene (G) and graphene oxide (GO) nano-layers.

PEG-modification is a proven method to enhance the hydrophilicity, protein resistance, and anti-biofouling properties of polymer coatings. It is considered as the gold standard interfacial modification technique such that the higher PEG content, the higher hydrophilicity, and lower protein adsorption, i.e., the initial stage of the biofouling process. Nevertheless, increasing the PEG content causes a higher water uptake, which declines the polymer mechanical strength and increases its hydrolytic degradation rate. Thus, an effective strategy to produce a limited-water-absorbing PEG-modified polymer is to force the majority of PEG molecules to migrate towards the interfacial region while the modification takes place. In the current paper, we report the synthesis and characterization of crosslinked polycarbonate-based polyurethanes (PU) containing methoxy polyethylene glycol (mPEG) dangling chains. We show that the simultaneous incorporation of a limited amount of a low-surface-energy dangling chain, i.e., 1-octadecanol (oDEC), along with mPEG, results in a considerably higher mPEG surface concentration, according to X-ray photoelectron spectroscopy (XPS), and a significantly lower water contact angle (WCA), up to 45° lower. We also put forward a reasonable mechanism for our outstanding observation and verified it through extensive experiments, e.g., dynamic WCA, Atomic force microscopy (AFM), and XPS. Moreover, we outline a delicate dynamic WCA experimental protocol, by which the smart and responsive behavior of our coatings is illustrated. Eventually, we examined the mixed hydrophobic/hydrophilic dangling chains strategy for low-protein adsorption applications, in which a great potential has been discovered.

Medical implants and devices are now being widely used in today's life. In most applications, they are coated with organic and/or inorganic materials in which high biocompatibility with human body and resistance against harsh environments expected during their use, are of prime importance. Interaction between cells and surface is a crucial matter in biomedicine and tissue engineering. In order to carry out normal metabolism, proliferation, and differentiation, cells prone to adhere onto the surface. Therefore, the cells adhesion will be strongly affected by the physiological activity of cells and surface properties of implants, as well. In this chapter, we will first describe the applications of coatings in medicine and introduce their different types for the devices we currently use. These include coatings on devices and implants either inside or outside of the body. This will be followed by designing criteria for superhydrophobic biomaterials applications such as temporally implants, contact lenses, controlled drug-release coatings as well as coatings on medical instruments. Due to these criteria, several surface properties are expected from these coatings such as controlled protein adsorption, cellular interaction, and bacterial growth. We will cover them by introducing some of novel examples being developed for cardiovascular and coronary stents and heart valves. Moreover, the strategies for designing such coatings will be pointed out. These start from conventional coatings followed by high-tech ones in which nanoparticles, hybrid organic/inorganic materials such as polyhedral oligomeric silsesquioxane (POSS), and sol-gel materials have been incorporated.

Icephobicity is the prevention of ice formation on a solid surface by repelling ice due to certain surface chemistry or topographical structure and it dates back to 1950. When ice forms on the surface of airplanes, aircraft wings, helicopters, ships, power transmission lines, telecommunication devices, and wind turbines, it jeopardizes their performance and therefore should be prevented. Scraping the surface mechanically, spraying glycol solvents on the surface, and heating the surface are typical strategies usually performed. All these methods are time-consuming, expensive, and have environmental risks. Coating the surface with appropriate layers, if possible, can lower the formation of ice on these objects. Different designs for ice-resistant coatings are available now but are mostly temporary and protect the surface for a limited number of cycles. There are various approaches to tackle this phenomenon: sacrificial coatings in which silicone oil is impregnated on the surface, ice-phobic coatings, and those covered by superhydrophobic coatings containing low surface energy components such as fluorine and silicone groups are today being employed. In this chapter, the mechanism behind the ice formation is firstly explained and the morphology of ice is described, this follows by the possible interactions it has with the surface. Different coating types including nanoparticle and low surface energy particle-based coatings, organic-inorganic coatings, self-assembled ones and those containing polyhedral oligomeric silsesquioxane (POSS) and sol-gel types are described.

Incorporation of hydrophilic and hydrophobic agents into a polymer backbone is an effective approach to control its interfacial characteristics. Segmented polyurethanes (PUs) are easy-fabricating and cost-effective candidates in this respect. In this work, we have synthesized polycarbonate (PC)-based PUs containing hydrophilic Polyethylene glycol (PEG) and hydrophobic Polyhedral Oligomeric Silsesquioxane (POSS) in the lab as well as in molecular dynamics simulations. We employed several experimental techniques and a coarse-grained (CG) molecular dynamics (MD) method to evaluate the morphology and microphase arrangement of PUs. We successfully synthesized superior hydrophilic and hydrophobic coatings by replacing some parts of the soft segment (PC) with PEG and the chain extender (1,4-butandiol) with POSS, respectively. Our CG MD simulations showed that POSS is dispersed in PC uniformly, while PEG is completely phase separated from PC and formed a lamellar structure. This was also confirmed by experimental thermal analysis. Eventually, water contact angle (WCA) measurements proved development of very hydrophilic (PU-PEG), slightly hydrophilic (PU), and very hydrophobic (PU-POSS) coatings. The surface free energy analysis indicated that POSS decreases polar and apolar components of surface free energy, while PU-PEG exhibits omniphilic behavior. The presence of PEG and POSS on the surface was also confirmed by contact angle and AFM measurements. According to MTT and LDH assays, PEG and POSS incorporation significantly enhanced the biocompatibility of PU such that PU-PEG and PU-POSS coatings become prospective candidates for biomedical applications.

A kinetic Monte Carlo method to simulate photodegradation of a polymer coating is applied to the weathering process of a polyester-urethane clearcoat during artificial exposure under different conditions. Firstly, the optimised simulation parameters that yield the best match with experimentally measured results on the depth-resolved ester and urethane bond fractions are determined and compared for two different aerobic exposure experiments (one in a Weather-Ometer (WOM) and one in a Suntest equipment). Secondly, several other quantities that are obtained from the simulations, but cannot be determined experimentally, are compared, such as the fraction of newly formed crosslink bonds, absorptivity states, oxidised states, the fraction of radicals, the concentration of oxygen and the total amount of remaining material. Depth-inhomogeneity of the rate of photon absorption leads to the formation of distinct depth gradients in the WOM simulation, while a much more homogeneous evolution is obtained for the Suntest-air simulation. Photo-oxidative damage in the WOM simulation is more concentrated on the upper layer of the coating, resulting in the extensive evaporation of highly oxidised material, whereas degradation in the Suntest-air simulation is more spread out over the entire coating thickness, resulting in less material loss.

The influence of the conditions of artificial degradation experiments on the photodegradation process of polyester-urethane clearcoats has been studied by comparing three types of exposure experiments with different conditions regarding the spectral power distribution (SPD), the exposure atmosphere (aerobic and anaerobic) and the presence of water. The presence of short wavelengths (λ

In this work we simulate the full sequence of steps that are also typically performed in an experimental approach when studying photo-degradation of a polymer coating, namely, i) sample preparation, ii) photo-degradation and iii) thermo-mechanical analysis of the material during photo-degradation. In the current paper, we focus on performing several molecular dynamics simulations to study the thermo-mechanical properties of a virgin thermoset coating as well as degraded ones. Using an atomistic structure that is obtained by fine-graining the mesoscopic structure, we obtain consistent correlations between the simulated thermo-mechanical properties of the material and those measured experimentally. In addition, it is shown that by using oscillatory strain fields in MD - instead of the commonly applied linear tensile/compression strain fields – one can acquire greater knowledge on the structure-property relation of polymeric materials. Eventually, we show that our simulation approach gives rise to a remarkable insight into the mechanism of the photo-degradation process.

This paper is devoted to the surface analysis of a polyester-urethane coating during weathering under different conditions using artificial weathering machines. By means of atomic force microscopy (AFM), the evolution of the surface topology of the coatings is studied. Degradation is shown to be a laterally inhomogeneous process. The presence of water facilitates material removal and leads to an increase in the surface roughness and consequently a gloss loss. In addition, by comparing degradation under aerobic and anaerobic conditions, it is shown that oxidation reactions are the main cause of lateral inhomogeneous degradation of coatings.

Designing surfaces with patterns of varying wettability is of significant importance for many applications. This fascinating feature is inspired by nature where it is vital for the survival of some living creatures. This research shows that an inherent incompatibility between different soft segments of segmented polyurethanes can play a pivotal role in designing such surfaces. We employed experimental techniques as well as coarse-grained molecular dynamics (CG MD) simulations to illustrate the microphase separation between soft segments with significantly different wettability. We started with poly(hexamethylene carbonate) polyurethane and partially replaced the polycarbonate diol (PC), the hydrophobic soft segment, with poly (ethylene glycol) (PEG), the superhydrophilic soft segment. Experimental analyses indicated a phase separation between PEG and PC, as soft segments, and our simulations merely confirmed it. This led to a core-shell morphology in which the hard segments are squeezed between two incompatible soft segments. Our combined simulation and experimental analyses proved a concurrent phase mixing of hard/soft segments with phase separation between soft segments. Moreover, the CG MD simulations elucidated the evolution of microphase organization as the polymerization proceeds and our further analysis shed light on the microarchitecture of the individual PU chains.

Transmission FTIR analysis of polyester-urethane coatings (PUC), that were degraded under different accelerated laboratory weathering conditions, are compared. The aim of this comparison is to deepen our insight into the chemical pathways of weathering of polyester-urethane coatings. We monitored the chemical changes for different environments, such as aerobic or anaerobic conditions as well as wet or dry conditions, in order to increase our insight into the effect of each individual stress factor, i.e., photons, oxygen, temperature and water, on the chemical pathways of weathering. We showed that the degradation of urethane groups proceeds via photo-oxidative pathways and that the ester groups mainly degrade via photolytic reactions. The ester bond scission accelerates after an initially-slow-rate stage of weathering in the presence of urethane groups. This is due to an increase in the optical absorptivity of the coating as a result of degradation under anaerobic conditions, as shown before. By means of a kinetic analysis using a combination of FTIR and UV–Vis spectroscopy results (obtained before), we found that a first-order kinetic model can perfectly describe the rate of ester bond scission during the weathering and that the increase in the rate of reaction is due to the increase in the light absorptivity of the coating as a result of degradation. Finally, using the interference fringes of FTIR spectra, we showed that evaporation and water-caused removal of degraded material cause a particularly pronounced decay in the thickness of the coating. In the absence of water spray, the material loss takes place in the same period as urethane groups decompose and stops afterwards, even though the ester bond scission proceeds with higher rates. This supports the hypothesis of photo-oxidative pathways for the urethane group decomposition and photolytic mechanisms for ester bond scission. Dark experiments showed that PUC coatings are highly resistant to hydrolysis and thermal degradation.

A numerical method to simulate reactions in a cross-linked polymer is developed and applied to the photodegradation process of polyester-urethane clearcoats during artificial exposure in a Weather-Ometer. This coarse-grained simulation method, which is based on a kinetic Monte Carlo scheme, is verified with experimental data on the depth-resolved changes in optical properties and chemical composition that have been previously determined. By modelling the depth-dependency of physical processes that occur in the coating, such as the absorption of photons and the diffusion of oxygen, the experimentally observed evolution of depth gradients in chemical composition can be well described by the simulation. A sensitivity analysis of individual simulation input parameters with respect to a set of resulting observables is performed and the results provide insight into the influence of specific reaction mechanisms on the overall degradation process and help to distinguish essential from less important processes. The values of input parameters that result in the most accurate simulation of the experimental data are determined with an optimisation procedure. In this way, the numerical values of several kinetic and physical parameters that are difficult to determine directly in an experimental way, such as various reaction rate constants, can be obtained from the simulations.

The effect of graphene (G) and graphene oxide (GO), used as the nanofiller in polymer nanocomposites (NC), on the structural and dynamic properties of polymer chains, has been studied by means of molecular dynamics (MD) simulations. Two polymers, i.e., poly(propylene) and poly(vinyl alcohol), are employed as matrices to cover a wider range of polymer�filler interactions. The local structural properties, e.g., density profile, average Rg, and end-to-end distance as well as dynamic properties, e.g., estimated translational and orientational relaxation times, of polymer chains are studied. In addition, the interaction energies are estimated between polymers and nanofillers for different hybrid systems using MD pullout simulations. Strong heterogeneities in polymer structural and dynamic properties have been observed such that chains are more oriented and exhibit slower dynamics in the vicinity of the nanofillers (G and GO) as compared to bulk. It is also found that the orientation of polymer chains at the interface is more influenced by the nanofiller in such a way that the more oriented polymer chains are observed in G-based NC for both polymers. However, the immobilization of polymer chains at the interface proves to be very much dependent on the polymer�filler interactions. (Figure presented.). Scopus

Chemical degradation of polymer coatings via a photo-oxidative pathway, denoted as photo-degradation, results in physical changes which, in spite of the long service life of coatings, eventually lead to failure of the material. Conventional molecular simulations cannot cope with this process with its wide range of time and length scales, related to the rare occurrence of ‘degradation events’ as compared to the time scale of structural relaxation of the polymer chains. Therefore a combination of suitable simulation techniques is needed to overcome this problem. By coupling a kinetic Monte Carlo simulation to a Dissipative Particle Dynamics method, a novel simulation approach has been developed that makes it possible to take into account chemical and physical pathways of the photo-degradation process. For a model polyester-urethane coating photo-degradation under inert conditions was studied with and without taking structural relaxation into account as well as by varying the ratio of reaction rate constants. For the model coating studied, taking physical relaxation into account proved to be essential for modeling the photo-degradation process.

In this article we studied the evolution of thermomechanical properties of a polyester-urethane coating during degradation under different degradation conditions, i.e., aerobic and anaerobic conditions with and without dry/wet cycling during degradation. Dynamic mechanical and thermal analyses show that under aerobic conditions the coatings become stiffer and more brittle in the glassy state. This stiffening is probably due to the increase in the amount of hydrogen bonding and the formation of oxidized groups which increase the polarity of the material and enhance the interactions of the polymer segments. However, oxidation reactions result in a considerable decrease in cross-link density and stiffness in the rubbery state. Both changes, in the glassy and rubbery states, give rise to development of internal stresses. These stresses increase as the degradation process proceeds. Nevertheless, for samples exposed to anaerobic conditions, the stiffness remains constant in the glassy state and the cross-link density slightly increases as a result of degradation. This reconfirms the dominance of the effect of oxidation reactions on the mechanical failure of the coatings. Oxygen permeation measurements show a more-or-less time-independent diffusion coefficient and a gradual decrease in solubility of oxygen as a function of exposure time. This results in a slight decrease in oxygen permeation (mainly in the early stage of the degradation) as degradation proceeds. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016, 54, 659–671

Polyester-urethane resins are important candidates for high performance, outdoor coating applications. Despite their relevance, quantitative information regarding the photodegradation of these materials is scarcely available. In the present study, a model polyester-urethane clearcoat without additives is artificially degraded and the changes in optical properties and chemical composition are studied by UV-VIS spectroscopy and FTIR-ATR microscopy, respectively. The change of the optical properties throughout the coating thickness is quantified and interpreted using a newly developed optical model. Chemical changes are quantified in a depth-resolved manner by combining FTIR-ATR microscopy with optical profilometry in order to visualise the time evolution of compositional gradients during photodegradation by accurate assignment of the correct depth position to all recorded ATR spectra. The rate of change for the concentration of several chemical entities in the model polyester-urethane was found to become constant after the initial stage of weathering. The loss of urethane crosslinks in the coating occurs faster and to a much larger extent as compared to ester bond scission. Results from the optical and the chemical characterisation are combined to propose a kinetic model for ester bond photolysis that provides an estimate of the quantum efficiency of this process.

Having phase-separated conductive and less-conductive domains is a common morphology in semiconducting polymer blends as it exists in the case of PEDOT:PSS, which is a representative example with a wide range of applications. In this paper, we constructed atomistic models for the interface between the PEDOT-rich (conductive) grains and the PSS-rich (less-conductive) phase through molecular dynamics simulations. Our models are obtained from experimentally relevant compositions, based on precise force field parameters, and through a robust relaxation procedure. We show that both PEDOT-rich and PSS-rich phases consist of PEDOT lamellae embedded in PSS chains. The size of these lamellae depends on the PEDOT concentration in each phase and our model predictions are in quantitative agreement with the experimental data. Furthermore, our models suggest that neither the phases nor the interfaces are entirely connected by π-π stacking. Thus, inter-lamellae tunnelling is essential for both intra- and inter-grain charge transport. We also show that a small increase (≈8 wt%) in the PEDOT concentration results in rather larger lamellae sizes, considerably more oriented lamellae, and slightly better inter-lamellae connectivity, which result in enhanced intra-grain conductivity. Moreover, we show how enhancing phase separation between PEDOT-rich and PSS-rich domains (similar to the effect of polar co-solvents)