Segmented Poly Research Articles

Siloxane-based segmented poly(urethane-urea) elastomers with enhanced mechanical properties, hydrophobicity and anti-calcification based on hierarchical phase separation for potential applications of polymeric heart valve

The polymeric heart valves have attracted considerable attention for treating valvular heart diseases with favorable biocompatibility, stability and adjustable mechanical properties. However, the thrombosis, calcification, and mechanical durability in the dynamic blood environment have limited further applications. Polycarbonate (PCDL) and polysiloxane (PDMS) had high flexibility, low toxicity, excellent hydrolytic and oxidative stability and efficient biocompatibility, but PCDL was susceptible to calcification and PDMS was susceptible to protein adsorption. To solve these difficulties, PDMS and PCDL were chosen as soft segments to combine the virtues of excellent biocompatibility, hydrolytic stability, and good anti-calcification and anti-protein adsorption, and a series of PCDL-PDMS poly(urethane-urea) elastomers (PCDL-PDMS PUU) were synthesized using a two-step polymerization reaction based on the amino-terminated polydimethylsiloxane (H2N-PDMS-NH2), polycarbonate diol (PCDL) and isophorone diisocyanate. The thermodynamic incompatibility between PDMS and PCDL and hierarchical hydrogen bonds were used to construct microscopic micro-separation, enabling the combination of enhanced mechanical strength, toughness, tear resistance and biocompatibility. The effect of the molar ratio of PCDL and PDMS and hierarchical H-bonding interactions on the physical properties, biostability and biocompatibility of PCDL-PDMS PUU were investigated. It was found the PCDL-PDMS PUU could achieve relatively stable mechanical strength behavior, and the Young’s modulus and tear strengths increased with the increasing proportion of H2N-PDMS-NH2. Meanwhile, PCDL-PDMS PUU showed low water uptake rate lower than 2 %, very good anti-hydrolysis performance, low hemolysis rate of less than 2 % and low adhesion to platelet cells. What’s more, PCDL-PDMS PUU showed enhanced calcification resistance when compared with a commercial polyurethane, ElastollanTM 1180A. Therefore, the results demonstrated that PCDL-PDMS PUU elastomers showed great potential to be explored as heart valves material considering high biostability, superior biocompatibility and mechanical performances.

Preparation and performance testing of novel bendable optically transparent fluorinated hyperbranched linear long chain segment poly(amide-imide) films

A series of fluorinated hyperbranched linear long-chain segment poly(amide-imide)s were prepared. Subsequently, a detailed comparative study of the optical properties of the hyperbranched PAI films with those of commercial films was carried out.

3-D Segmented Gate Concept: A New IGBT Solution for Reduced Loss and Improved Safe-Operating Area

In this article, the “segmented gate (SG)” concept is proposed and implemented in trench gate to realize both low loss and wide safe-operating area (SOA) for insulated-gate bipolar transistors (IGBTs). The poly gate of the proposed IGBT is split into segments along the trench and each segmented poly gate is surrounded by the poly emitter. This unique 3-D trench architecture is demonstrated under numerical studies to be highly effective in enhancing the short-circuit ruggedness, the turn-off capability, and the latch-up immunity. It enables a 37% reduction in saturation current and a 90% reduction in Miller capacitance. The proposed design also shows an improved trade-off relationship between ON-state voltage and turn-off loss. For the same turn-off loss, the ON-state voltage of the proposed IGBT is reduced by 0.25 V when compared with the conventional carrier-stored trench IGBT.

Preparation and characterization of a mussel-inspired and programmable PDA@MXene/PNIPAM hydrogel actuator with ultrafast temperature and NIR responsiveness

In recent years, smart hydrogels have been widely applied to various types of hydrogel actuators due to their unique stimulus responsibility, such as temperature responsiveness, near-infrared (NIR) light responsiveness, pH responsiveness, etc. Herein, segmented poly (N-isopropyl acrylamide) (PNIPAM) based hydrogel actuators with both temperature and NIR light actuation behaviors were constructed. Polydopamine (PDA) was firstly used to modify MXene nanosheets to fabricate an efficient photothermal conversion material. Then they were added into PNIPAM matrix to prepare PDA@MXene/PNIPAM hydrogels. The prepared PDA@MXene/PNIPAM hydrogels exhibited three-dimensional network structure with the tensile strength of 26.84 kPa, and they were successfully assembled into segmented hydrogel actuators. The assembled segmented hydrogel actuator exhibited high bending angle of 470° in 1.75 s in 55 °C hot water and bending angle of 203° in 15 s when irradiated by 6 W/cm2 NIR light. The segmented hydrogel actuators displayed good programmable actuation performance. Finally, they were applied as smart devices, such as hydrogel hook for grasping object, switch for controlling circuit and valve for governing fluid flow. This work provides a novel strategy for fabricating programmable hydrogel actuators and will inspire new ideas and constructions for smart soft hydrogel actuators.

Synthesis of bio-based poly(ester-ether) elastomers from 2,5-furandicarboxylic acid (FDCA) with excellent thermo-mechanical properties

As a novel polyester possessing high melting temperature and well crystallization ability, poly(1,4-cyclohexanedimethylene furandicarboxylate) (PCF), produced from bio-based 2,5-furandicarboxylic acid and 1, 4-cyclohexanedimethanol, could be used as promising hard segment to develop new bio-based thermoplastic poly(ether-ester) elastomer (TPEE). Multiblock poly(ether-ester)s based on PCF, with molecular weight (Mn) of soft segments poly(tetramethylene glycol) (PTMG) ranging from 250 to 2900 g/mol while maintaining the weight fraction at 70%, were synthesized to investigate the effects of soft segments length on microphase structure and thermodynamic properties of copolymers. The results show that the increase in Mn of the soft segment promotes the microphase separation of the copolymers. Macroscopically, copolymers have excellent comprehensive properties. Tm was promoted from 126.0 to 228.7 °C, and Td,5% was higher than 320 °C. The tensile strength and modulus of resulting copolymers were within the range of 14–26 MPa and 29–53 MPa, respectively, with elongation at break exceeding 550%. The copolymer exhibited elastic recovery ratio of 75.5% at 200% strain when the Mn of PTMG unit was 2000 g/mol. This work introduces a new bio-based TPEE and enriches a detailed understanding of the impact of soft segments length on the structural properties of TPEE, which is fundamental to design tailor-made TPEE with desired properties.

High temperature performance adhesive derived from randomly segmented poly (imide siloxane) copolymer

The thermal resistance of the randomly segmented poly (imide siloxane) copolymer in adhesive form was improved as the synthetic polymer with siloxane (linked by imide units with the random form of poly (imide siloxane) copolymer). The adhesion strength of the randomly segmented poly (imide siloxane) copolymer adhesive was performed at 1 mm thickness with 6.28 E-6 m2 (6.28 mm2) surface area in a 1 cm radius. After this copolymer was adhered to the surface of the poly (methyl methacrylate) used as a space-grade thermoplastic substrate there was no failure or any dimensional change on the copolymer adhesive at the end of ten days. This result indicated that the strong bonding was achieved at 1162,89 N/m2 on the surface of the thermoplastic substrate used as the substrate in the adhesion test of the randomly segmented poly (imide siloxane) copolymer adhesive) after the cooling processing of the adhesive. The cooling processing was applied to the adhesive for the examination of the adhesive performance. In the cooling process, the adhesive has been kept cold (-5 °C) in dark for 6 months. The bonding properties of the adhesive including Si (111) crystalline were investigated and the results indicated that the adhesive was resistant to high-temperature applications until 350 °C. The formation of polysilicon-11 (as the silicone bulk in 3D) in the adhesive was significant to solve the thermal problems for the generation of the low-dimensional system (called quantum confinement effect).

Synthesis and Characterization of New Polycarbonate-Based Poly(thiourethane-urethane)s.

The new segmented poly(thiourethane-urethane)s (PTURs) based on 1,1′-methanediylbis(4-isocyanatocyclohexane) (HMDI, Desmodur W®), polycarbonate diol (PCD, Desmophen C2200) and (methanediyldibenzene-4,1-diyl)dimethanethiol were synthesized by one-step melt polyaddition method. The obtained PTURs, with a content of 30–60 wt% of the hard segments (HS), were tested in which the influence of changes in the HS content on their properties was determined. The polymers were characterized by Fourier transform infrared spectroscopy (FTIR), gel permeation chromatography (GPC), thermal analysis (DSC, TGA) and thermomechanical analysis (DMTA). Additionally, tensile strength, optical (refractive index, UV-VIS and color) and surface properties of the obtained polymers (contact angle and surface free energy) and adhesion to copper were examined. FTIR analysis verified the supposed structure of the polymers obtained and showed a complete conversion of the isocyanate groups. TGA analysis confirmed the relatively good thermal stability of the polymers. On the other hand, after performing the DSC analysis, it was possible to state that the obtained materials were partially or completely amorphous, and the microphase separation decreased with increasing HS content in the polymer. Similar observations were made from the DMTA data. In addition, the hardness, tensile strength, modulus of elasticity, storage modulus, adhesion to copper, refractive index and total free surface energy increased with increasing HS content in the polymer.

New Segmented Poly(Thiourethane-Urethane)s Based on Poly(ε-Caprolactone)Diol Soft Segment: Synthesis and Characterization.

New segmented poly(thiourethane-urethane)s (SPTURs) were synthesized by the reaction of 1,1′-methanediylbis (4-isocyanatocyclohexane) (Desmodur W®, HMDI) and poly(ε-caprolactone)diol (PCL) and (methanediyldibenzene-4,1-diyl)dimethanethiol as nonconventional polymer chain extender. FTIR spectroscopy was used for the structural analysis of obtained polymers. The molecular weight distribution was examined by GPC chromatography. Based on the measured contact angles, free surface energy parameters were calculated. Thermal properties of polymers were examined by DSC and TGA, while viscoelastic properties were measured by DMTA. The tensile, adhesive and optical properties were also investigated for the obtained polymers. It was shown that SPTURs were transparent or partially transparent solids with high molar masses up to 84,300 Da. These polymers showed a good resistance to hydrolysis during incubation in Optylite® physiological saline over 8 weeks. Obtained polymers possessed a tensile strength of up to 43.26 MPa, hardness of up to 96.25/59.00 Sh A/D and adhesion to copper of 14.66 MPa. The surface properties of the obtained polymers show that all obtained SPTURs were hydrophilic (CAs for water between 64.07° and 73.12°) with calculated SFE up to 46.69 mN/m.

Additive manufacturing of bioresorbable poly(ester‐urethane)/glass‐ceramic composite scaffolds

AbstractThe development of three‐dimensionally printed implants for biomaterial‐based tissue engineering applications is currently an active research field. In order to meet the requirements of several applications, new biocompatible and bioresorbable polymer‐based materials are needed to design tailor‐made polymer/composite scaffolds. In the last decade, bioresorbable segmented poly(ester‐urethanes) (SPEU) have been extensively investigated for their applications in tissue engineering and many biomedical devices. In this work, 3D printed poly(ester‐urethane)/bioceramic composite scaffolds were successfully fabricated by fused deposition modeling for the first time. A twin‐screw extruder was used for making the SPEU composite filaments containing 5% and 10% wt/wt of glass‐ceramic particles. Both filaments and scaffolds were physically and chemically studied in terms of morphology, thermal properties, wettability, and mechanical properties. The resulting composite scaffolds could be remarkably interesting for potential applications in soft tissue engineering.

Synthesis and covalent immobilization of redox-active metallopolymers for organic phase electrochemistry

Redox-active metallopolymers are promising stimuli-responsive platforms for a range of applications including sensing, energy storage, and selective separations. In particular, heterogeneously-functionalized metallopolymers can modulate the capture and release of target molecules, driven by redox electron-transfer. However, prior metallopolymer-functionalized electrodes have been fabricated by non-covalent methods, and tailored for aqueous phase applications. As such, despite the existing potential for heterogeneous applications in organic phase, there are significant constraints to the stability of metallopolymers in organic solvents, including high solubility in solvents such as chloroform or tetrahydrofuran. We propose the immobilization of thiol-functionalized redox-active metallopolymers on metallic surfaces as a facile way to enhance stability and cyclability in organic media, and thus broaden the applicability of redox-metallopolymers for organic phase applications. We explore the anionic polymerization of metal-containing monomers vinylferrocene (VFc) and ferrocenyldimethylsilane (FS), and their thiol end-functionalization by living anionic polymerization strategies. PFS and PVFc with molar masses ranging from 1800 to 49900 g mol−1 and 2900 to 6300 g mol−1 respectively were prepared with a segment of poly(ethylene sulfide), as characterized by size-exclusion chromatography, NMR spectroscopy, MALDI/ToF, thermogravimetry, and elemental analysis. Both metallopolymers were immobilized on gold substrates by a grafting-to protocol, with demonstrated redox-responsiveness by electrochemical control. In the case of immobilized PVFc, operando electrochemical testing demonstrated the stable and reversible electrochemical cycling capabilities (>74% maximum current retained after 100 oxidation/reduction cycles) in several organic solvents including chloroform, tetrahydrofuran, ethanol, methanol, acetonitrile, and acetone. Immobilized PFS was stable in chloroform, with a 83% maximum current retained after 100 oxidation/reduction cycles. We envision future applications of these covalently immobilized metallopolymers for a broad range of fields from selective separations to sensing and energy storage.

XPS and ToF-SIMS Characterization of New Biodegradable Poly(Peptide-Urethane-Urea) Block Copolymers.

New, linear, segmented poly(peptide-urethane-urea) (PPUU) block copolymers are synthesized and their surface compositions are characterized with angle dependent X-ray photoelectron spectroscopy (ADXPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). These new PPUU block copolymers contain three types of segments. The soft segment (SS) is poly(caprolactone diol) (PCL). The hard segment is lysine diisocyanate with a hydrazine chain extender. The oligopeptide segment (OPS) contains three types of amino acids (proline, hydroxyproline, and glycine). Incorporation of the OPS into the polyurethane backbone is done to provide a synthetic polymer material with controllable biodegradation properties. As biodegradation processes normally are initiated at the interface between the biomaterial and the living tissue, it is important to characterize the surface composition of biomaterials. ADXPS and ToF-SIMS results show that the surfaces of all four polymers are enriched with the PCL SS, the most hydrophobic component of the three polymer segments.

On arginine‐based polyurethane‐blends specific to vascular prostheses

AbstractPolymer blends based on Tecoflex™ and an experimental aliphatic polyurethane (HMDI‐PCL‐arginine stands for 4,4 (metylene‐biscyclohexyl) isocyanate ‐ poly (ε caprolactone) diol, SPUUR stands for segmented poly(urea)urethanes using amino acid of L‐Arginine as chain extender) were obtained by solvent casting, and further studied by fourier transform infrared (FTIR) and Raman spectroscopy, differential scanning calorimetry (DSC), thermogravimetric analysis, and X‐ray diffraction (XRD). Their biological performances were assessed in terms of hemocompatibility and Human umbilical vein endothelial cell (HUVEC) cytotoxicity. Tensile properties of dumbbell specimens were compared to longitudinal and circumferential tensile properties of tubular vascular graft. FTIR showed that as the SPUUR content increased in the blend, absorptions at 2860 cm−1 increased, carbonyl absorptions at 1724 cm−1 broaden and the small peak at 2796 cm−1, typical of Tecoflex™ disappeared. Raman spectroscopy showed that the low intensity carbonyl absorption at 1724 cm−1 also increased with SPUUR content. DSC allowed detection of PCL soft segment melting (Tm = 50°C) in agreement with X‐ray reflections at 21.3° and 23.6°, assigned to SPUUR. However, no improvements in thermal stability were detected by TGA by blending. The addition of SPUUR to Tecoflex™ improved hemocompatibility and HUVEC cytotoxicity. The vascular grafts performance showed that 40% SPUUR blends exhibited the highest force in the longitudinal test whereas 50% SPUUR blends showed the highest circumferential force. Pressure burst strength was higher than 1000 mmHg for all blends. Overall, these blends can be used for high caliber vascular grafts.

Ring-Opening Metathesis Polymerization of δ-Pinene: Well-Defined Polyolefins from Pine Sap.

Well-controlled ring-opening metathesis polymerization (ROMP) of δ-pinene is reported. The monomer is produced through a facile, metal-free, three-step synthesis from highly abundant and sustainable α-pinene. Using Grubbs third-generation catalyst, δ-pinene undergoes ROMP to high conversion (>95%) with molar mass up to 70 kg mol-1 and narrow dispersity (<1.2). A highly regioregular propagation mechanism was concluded by NMR spectroscopic analysis that revealed a head-to-tail (HT, >95%) microstructure and high trans content (>98%). Successful ROMP is corroborated with density functional theory calculations on δ-pinene's ring strain energy (∼35 kJ mol-1). Poly(δ-pinene) has a high glass transition temperature (∼104 °C) and a unique chiral microstructure bearing gem-dimethylcyclobutane rings. Controlled ROMP also allowed the synthesis of block copolymers containing segments of poly(δ-pinene) and polynorbornene which are discussed. Finally, bulk polymerization of δ-pinene is possible, indicating a greener approach to these materials, albeit with some loss of control.

Segmented Poly(urea)urethane Nanoparticles: Size Optimization Using Taguchi Experimental Design and Nanoprecipitation Method

Background: Polymeric nanomaterials are important for developing drug delivery systems. The control of nanoparticle size, polydispersity, and morphology in these systems are important goals. Therefore, different strategies have been explored depending on the type of materials used. Objective: To prepare biodegradable segmented poly(urea)urethane nanoparticles and to optimize the nanoparticle size and polydispersity using an experimental design methodology. Methods: In this work, a biodegradable segmented poly(urea)urethane (SPUU) was synthesized. This polymer was used for nanoparticle preparation by the nanoprecipitation technique in the context of the experimental design methodology Taguchi L9. SPUU and nanoparticles were characterized using Fourier transformed infrared, proton nuclear magnetic resonance, transmission electron microscopy, scanning electron microscopy, and dynamic light scattering. Results: This methodology produced polymeric nanoparticles with mean sizes in the range of 60 to 220 nm with polydispersity in the range of 0.077 to 0.233. The statistical analysis showed that the SPUU concentration and the stirring speed were the most influential parameters, while temperature, at the studied range, did not show a relevant effect. Conclusion: The analysis of Taguchi’s experimental design resulted in the optimization of parameters determining SPUU-NPs’ size. Nanoparticles from 60 nm of effective diameter were obtained at low polymer concentration and higher stirring speed.

Novel three‐dimensional printing of poly(ester urethane) scaffolds for biomedical applications

AbstractTissue engineering requires highly porous complex structures with interconnected pores and tightly controlled pore sizes, added to customized production. Additive manufacturing (AM) is nowadays one of the most suitable technologies for the preparation of structures with strictly defined complex three‐dimensional architectures. Moreover, computed tomography and magnetic resonance imaging can be employed to obtain personalized medical devices. Fused deposition modeling (FDM) is one of the most common, easiest, and cost‐effective AM techniques to obtain 3D objects from a wide variety of materials. However, there is a lack of bioresorbable materials that can fit the increasing demand for biomedical applications requiring stiff elastomers. In this work, a series of bioresorbable segmented poly(ester urethanes) (SPEU) with high hard segment content was synthesized and physicochemically characterized. The materials with higher thermal stability were processed into homogeneous filaments by hot‐melt extrusion with no need for additives nor plasticizers. These filaments were evaluated for FDM, and structures with controlled porosity, filament diameter, and in‐plane pore size could be easily obtained by modifying the printing parameters. Regarding SPEU mechanical properties, the obtained scaffolds could be promising for cartilage tissue engineering applications.

Mesostructure of Composite Materials Based on Segmented Poly(Urethane Imide) Containing Ferrite Nanoparticles

The mesostructure of segmented poly(urethane imide) containing 4–10 wt % CoFe2O4 or Al3Fe5O12 nanoparticles was experimentally studied by small-angle polarized neutron scattering, which can analyze the nuclear and magnetic subsystems of the obtained composites. The transformation of the domain structure of the magnetic elastomers based on poly(urethane imide) was investigated at various concentrations, chemical compositions, and localizations of ferrite nanoparticles in polymer chains. The dynamics of the change in the segmental mobility of soft blocks during heating of samples was characterized by magnetic–nuclear interference scattering. The experiments detected changes in the supramolecular structure of the multiblock copolymer, which depended on the percentage and type of nanoparticles. The correlation radii were determined in the magnetic subsystem of ferrite nanoparticles embedded in hard aromatic blocks of poly(urethane imide) as nodes of intermolecular crosslinkers and chain extenders. The temperature dependence was analyzed for the intensity of small-angle nuclear scattering by poly(urethane imide) and magnetic elastomers based on it, under the conditions of the transition of soft aliphatic segments from the glassy to the highly elastic state.

Facile Method for Surface-Grafted Chitooligosaccharide on Medical Segmented Poly(ester-urethane) Film to Improve Surface Biocompatibility.

In the paper, the chitooligosaccharide (CHO) was surface-grafted on the medical segmented poly(ester-urethane) (SPU) film by a facile two-step procedure to improve the surface biocompatibility. By chemical treatment of SPU film with hexamethylene diisocyanate under mild reaction condition, free -NCO groups were first introduced on the surface with high grafting density, which were then coupled with -NH2 groups of CHO to immobilize CHO on the SPU surface (SPU-CHO). The CHO-covered surface was characterized by FT-IR and water contact angle test. Due to the hydrophilicity of CHO, the SPU-CHO possessed higher surface hydrophilicity and faster hydrolytic degradation rate than blank SPU. The almost overlapping stress-strain curves of SPU and SPU-CHO films demonstrated that the chemical treatments had little destruction on the intrinsic properties of the substrate. In addition, the significant inhibition of platelet adhesion and protein adsorption on CHO-covered surface endowed SPU-CHO an outstanding surface biocompatibility (especially blood compatibility). These results indicated that the CHO-grafted SPU was a promising candidate as blood-contacting biomaterial for biomedical applications.

The Thermal Stability and Mechanical Properties of Non-Segregating Blends of Polyimides with Copoly(Urethane-Imide)s

The series of compositions containing thermodynamically incompatible flexible blocks of aliphatic polyesters and rigid blocks of aromatic bis (urethane) imides in the volume of polymers was obtained on the basis of multiblock (segmented) poly (urethane-imides) and related aromatic polyimides. The series includes segmented poly (urethane-imides) with different relative content of flexible and rigid blocks, non-segregating mixtures of poly (urethane-imides) and thermoplastic partially crystalline polyimide, statistical copolymers of poly (urethane-imide) with imide, and non-segregating mixtures of statistical copolymers with thermoplastic polyimide. The derived polymer systems were studied using thermogravimetric analysis, differential scanning calorimetry, and dynamic mechanical analysis. The deformation and strength properties of film samples are determined. It is shown that the properties of the studied polymers change as their content of imides blocks increases, and the transition from thermoplastic poly (urethane-imide) elastomers to thermoplastic polyimides is observed.

Characterization and gas transport properties of UV-irradiated polydimethylsiloxane (PDMS)-containing polyimide copolymer membranes

The influence of UV irradiation on gas permeation properties of random segmented poly (imide-siloxane) (PIS) copolymer films was investigated. Random segmented copolymers were synthesized via ester-acid imidization from 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) and 3,3′,4,4′-benzophenone tetracarboxylic dianhydride (BTDA) in a 7:3 M ratio with 2,4-diamino mesitylene (DAM) and varying amounts of a diamine terminated polydimethylsiloxane (PDMS) oligomer (Mn = 3000 g/mol). Solvent cast films of these copolymers were UV-irradiated on both sides in air at 365 nm, which induced crosslinking and photooxidation. Pure-gas permeabilities of H2, O2, N2, CH4, and CO2 were measured with upstream pressures ranging from 2 to 18 atm at 35 °C. Gas permeability coefficients of a series of PIS copolymers decreased, and selectivity of all gas pairs increased after UV irradiation due to a decrease in free volume by UV crosslinking and photooxidation.

Dissipative particle dynamics simulation of microphase separation in polyurethane urea nanocomposites

Vertically aligned carbon nanotube reinforced segmented poly(urethane-urea) (PUU) polymer nanocomposites (A-CNT/PUU PNCs) have been synthesized and proven to be potential candidates for novel materials with high mechanical strength, toughness, and thermal energy dissipation. It has been experimentally observed that incorporation of A-CNTs could induce interface-mediated nanophases of PUU along the A-CNTs axes. Here, we employed dissipative particle dynamics (DPD) computer simulations to elucidate the nature of the filler and matrix relationship in polyurethane composites at a molecular level. Diamine and diisocyante, the constituents of hard segments (domains), were found to have a propensity to adsorb onto the CNTs. This phenomenon is presumably facilitated by their greater thermodynamic compatibility with CNTs than the soft segments. Additionally, increasing the polymer's effective density leads to a rise in thermodynamic incompatibility of the polymer blocks. Hard domain aggregation around the CNTs' axes and between CNTs was also found to increase the conformational entropy. At the higher CNT loading, when the inter-CNT spacing becomes comparable with the distance between hard domain clusters, these domains form nanophase columns. Finally, simulation results agree with our previous PUU experimental data.