Liquid Crystal Polyesters Research Articles

Decoding high-frequency dielectric loss of Poly(ester imide)s: Molecular simulation and experiment validation

Polyimides (PIs) are essential materials for electronic and high-frequency communication applications, often face challenges with high dielectric loss. Drawing inspiration from low-dielectric-loss liquid crystal polyesters, ester groups have been introduced into PI backbones to develop poly (ester imide)s (PEsIs). This study delved into various PEsIs, aiming to reduce dielectric loss at high frequencies and to understand the molecular mechanisms behind this improvement. Selection and design of PEsIs were based on four key factors: the number of ester groups, substitution positions, side substituents and intermolecular interactions. The results indicated that the high-frequency dielectric loss of PEsIs, specifically at a frequency of 10 GHz, decreases with an increased number of ester groups. For isomeric PEsIs systems, introducing ester groups into the dianhydride part notably reduced the dielectric loss. The modes of bonding between the phenyl ring and the ester group in PI structures also impacted the dielectric loss. The configuration with an O-linked isomer showed a lower value of dielectric loss. On the other hand, introducing hydrogen bonding into PEsIs were observed to contribute a negative impact on the reduction of dielectric loss. Based on these theoretical findings, two PEsIs structures, which were identified as low-dielectric-loss PEsIs candidates, were successfully synthesized. Their dielectric loss factors at 10 GHz were measured experimentally as 0.00153 and 0.00134, thereby confirming the reliability of the theoretical results.

Catalytic effects of sodium salts with varied anionic pairs on the polymerization of liquid crystal polyesters

Catalytic effects of sodium salts with varied anionic pairs on the polymerization of liquid crystal polyesters

Structural Regulation of Microcellular Thermotropic Liquid Crystalline Polymer with Low‐Dielectric Properties During Supercritical Fluid Foaming Process

With the development of radio technology, 5G electronic equipment has higher requirements for materials. This has become an imperative matter to realize the controllable preparation of Thermotropic liquid crystal polyester (TLCP) foams with homogeneous microcellular. Accordingly, the foaming behavior of TLCP in isotropic state is investigated. TLCP foams are prepared by a one‐step rapid depressurization foaming method at different temperature pressures, with cell diameter in the range of 67.5–283.9 μm and the material density in the range of 0.37–0.25 g/cm3. In order to broaden the distribution of cell diameter and the density of TLCP foams, the mixture foaming agent of N2 and CO2 is used in foaming process. When mixture foaming agents are used, the cell diameter is widened to the range of 40.5–283.9 μm, and the material density is widened to the range of 0.70–0.25 g/cm3, which realizes the controllable preparation of cell diameter and material density of TLCP. The dielectric constant and dielectric loss of TLCP foams can be as low as 1.35‰ and 0.85‰ at 10 GHz, respectively. The structural regulation of low‐dielectric TLCP microcellular materials is achieved for the first time by way of varying the temperature, pressure, and co‐blowing agent ratio.

Polyimide films with ultralow dielectric loss for 5G applications: Influence and mechanism of ester groups in molecular chains

Polyimides are ideal candidates for 5G high-frequency communications due to their good thermal stability, mechanical properties and processability. However, the exploration of how to reduce their high-frequency dissipation factor (Df) remains an urgent and alluring challenge. Inspired by the molecular structure of liquid crystal polyester, which is insensitive to high-frequency electric fields, here we design two series of polyimides derived from diamines with multiple ester groups (AXEB, X = 1, 2 or 3) and 4,4′-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) or p-phenylene bis (trimellitate anhydride) (TA2EB). We investigated the effects of ester number on the aggregation structure, water absorption, dielectric properties, heat resistance and mechanical properties of the polyimides and find that the Df of the multiple ester-containing polyimides decreases rapidly with increasing frequency and number of ester groups. Wide-angle X-ray diffraction analysis, polarized optical microscopy observations and molecular dynamics simulations show that the unique properties of these polyimides benefit from the tight packing of the molecular chain and the strong intermolecular interaction force caused by the ester group, as well as the resulting prolonged dipole relaxation time and the greatly reduced water absorption. Therefore, the polyimide films show extremely low Df values of 0.0030 for AXEB-6FDA and 0.0013 for AXEB-TA2EB. Furthermore, AXEB-TA2EB also shows excellent thermal stability, mechanical properties, electrical properties and permittivity. More importantly, their ultralow moisture rate (<0.83 %) ensures that the high-frequency Df remains stable in different humid environments, even after soaking in water. This method can also be extended to other polymers, thus providing a new strategy for the design of low dielectric loss materials.

Crystal structure simulation of cationic cholesteric Liquid-Crystal polyesters. Non-Viral vectors

The crystal structure of six cationic cholesteric liquid crystal polyesters with choline, ammonium, and amide end groups are reported: PTOBEE-Choline [(C26H20O8)n-C5H13N]; PTOBDME-Choline [(C34H36O8)n-C5H13N]; PTOBEE-Ammonium [(C26H20O8)n-C5H13N]; PTOBDME-Ammonium [(C34H36O8)n-C5H13N]; PTOBEE-Amide (C26H19O9N)n and PTOBUME-Amide (C33H33O9N)n, have demonstrated non-viral vector properties in gene therapy by delivering DNA to the cell nucleus. They were synthesized by functionalization of precursor racemic polyesters via a condensation reaction between 4,4′-(terephthaloyl-di-oxydibenzoic chloride) (TOBC) and the racemic mixture of glycol (R-S-1,2-butanediol) or (R-S-1,2-dodecanediol), respectively. The resulting helical macromolecular structures exhibit unexpected optical activity and chiral morphology, previously attributed to the kinetic resolution of one preferable helical conformer of the possible four observed by NMR. Conformational analysis and energy minimization are performed on the four helical conformer monomeric models which are then polymerized to obtain helical chains. Three levels of chirality were observed in these polymer structures. Crystal models are built in triclinic primitive P1cells, with their molecular chains oriented parallel to the Z-axis (c lattice parameter equal to the helical pitch length), the cell parameters are obtained by performing geometry optimization tasks. A raw estimation of the relative weight of the four possible helical conformers on each synthetic cationic polymer has been performed on ideal mixtures considering their approximate known crystal structure with their experimental X-ray powder diffraction by Powder Quantitative Phase Analysis. The results would confirm the theory of the preferable recrystallization of a diastereoisomer, among the four possible, during the synthetic procedures. These findings shed light on the observed optical activity and provide insights into the crystal structure of these cationic polymers. The morphology of the cationic polymers is studied by ESEM in wet samples and crystals after drying the solvent.

Effects of Smectic Layer Deformation on Mechanical Properties of Glassy Liquid Crystal Polymer Fibers

AbstractIn this work, it is demonstrated that the stress response of glassy smectic liquid crystal (LC) polymer fibers is largely dependent on layer deformations. Fibers with smectic layers stacked along the fiber axis (fiber A), prepared by stretching a molten main‐chain LC polyester, deform the layers by tensile deformation in the LC state, yielding fibers with layers tilted from the fiber axis (fiber B) and those with divided layers (fiber C). These fibers in the glassy LC state differ in Young's modulus (E), yield stress and strain (σy, εσy), and strain at break (εb). Fiber A has εb = 30%; however, fiber B is much more ductile (εb &gt; 290%). Fiber C has higher E = 0.97 GPa and σy = 82 MPa than fiber A (E = 0.33 MPa and σy = 33 MPa). Annealing fiber C in the LC state yields fiber D with large‐area layers, similar to fiber A. Fiber D has E = 0.74 GPa and σy = 25 MPa, comparable to those of fiber A. Thus, dividing layers improves E and σy. This strengthening of glassy smectic LC by dividing layers applies to other polymers with layered structures, including lamellar block copolymers and semi‐crystalline polymers.

Short aramid fiber reinforced thermotropic liquid crystalline polyester composites: Fabrication, thermal, and mechanical properties

We conducted a study to analyze the impact of short aramid fibers (AFs) on the melt-rheological behavior, thermal transition, thermal stability, and mechanical durability of thermotropic liquid crystal polyesters (TLCPs). By using different AF loading contents ranging from 3–15 wt%, we produced TLCP matrix composites through masterbatch-based melt-compounding and injection-molding. The SEM images and FT-IR spectra demonstrate that the AFs are dispersed in the TLCP matrix with a microfibrillar structure through good interfacial adhesion caused by specific intermolecular interactions between the TLCP and AFs. As a result, the complex viscosity, shear storage/loss moduli, and thermal transition (melt-crystallization, glass transition, and melting) temperatures of the composites increase with increasing AF filler content. However, the melt-crystallization and melting enthalpies increase only at low AF loading contents of 3–5 wt%. At high AF contents of 7–15wt%, the enthalpies decrease owing to the partial aggregation of AF fillers. The thermogravimetric analysis proves that the thermal stability of TLCP/AF composites improves when the AF filler is introduced. The dynamic mechanical analysis using the stepped isothermal method shows that the addition of 5 wt% AF to the TLCP leads to an approximately 150% improvement in elastic moduli and long-term mechanical durability at elevated temperatures.

Synthesis and properties of high performance biobased liquid crystal polyester based on furandicarboxylic acid and sebacic acid

In this study, a series of high-performance biobased liquid crystal copolyesters derived from 6-hydroxy-2-naphthoic acid (HNA), 4, 4ʹ-Dihydroxybiphenyl (BP), biobased 2,5-furandicarboxylic acid (FDCA) and sebacic acid (SeA) were successfully designed and prepared via “one-pot” melt polycondensation method. The addition of nonlinear and rigid FDCA units broke the regularity of the molecular chain but increased the chain rigidity, thus, endowing the unique thermal behavior, which the melting temperature decreased from 163.0 to 125.3 ℃, while the glass transition temperature decreased first and then increased slightly to 75.7 ℃ as increased the FDCA units to 7.5 mol%. Furthermore, DSC and XRD results showed that a small amount (1 mol%) of FDCA units did not impair crystallization ability of the copolyesters, whereas excess of FDCA hindered the molecular chain packing. The DMA results also demonstrated that the addition of FDCA restricts the chain motion and improves the rigidity of the copolyester as reflected by the higher storage modulus. The incorporation of nonlinear FDCA units lowered the initial degradation temperature slightly, but still exhibited enough thermal stability to be melt processed as compared with its relative low melting temperatures. The copolyesters exhibited a broad temperature range of nematic liquid crystal phase as well as shear thinning and viscous melt flow behavior, which were beneficial for its melt processing. The tensile strength and modulus of the injection molded splines were in range of 82.51–103.27 MPa and 2.05–2.72 GPa, respectively, which were much higher than the common biobased copolyesters such as PLA, PCL and other FDCA-containing polyesters. The increased modulus and decreased fracture strain of the copolyesters containing FDCA units further verified the high rigidity of the molecular chain. Moreover, the in-vitro cytotoxicity and water contact angle results proved that the copolyesters have good biocompatibility. The resulted copolyesters combined with excellent melt processing ability, mechanical property and good biocompatibility have great promising applications as biomedical and biodegradable materials.

Enhanced Thermal Conductivities of Liquid Crystal Polyesters from Controlled Structure of Molecular Chains by Introducing Different Dicarboxylic Acid Monomers.

Enhancing thermal conductivity coefficient (λ) of liquid crystal polyesters would further widen their application in electronics and electricals. In this work, a kind of biphenyl-based dihydroxy monomer is synthesized using 4, 4'-biphenyl (BP) and triethylene glycol (TEG) as raw material, which further reacts with three different dicarboxylic acids (succinic acid, p-phenylenediacetic acid, and terephthalic acid, respectively) by melt polycondensation to prepare intrinsically highly thermally conductive poly 4', 4”'-[1, 2-ethanediyl-bis(oxy-2, 1-ethanediyloxy)]-bis(p-hydroxybiphenyl) succinate (PEOS), poly 4', 4”'-[1, 2-ethanediyl-bis(oxy-2, 1-ethanediyloxy)]-bis(p-hydroxybiphenyl) p-phenyldiacetate (PEOP) and poly 4', 4”'-[1, 2-ethanediyl-bis(oxy-2, 1-ethanediyloxy)]-bis(p-hydroxybiphenyl) terephthalate (PEOT), collectively called biphenyl-based liquid crystal polyesters (B-LCPE). The results show that B-LCPE possess the desired molecular structure, exhibit smectic phase in liquid crystal range and semicrystalline polymers at room temperature, and possess excellent intrinsic thermal conductivities, thermal stabilities, and mechanical properties. λ of PEOT is 0.51 W/(m·K), significantly exceeds that of polyethylene terephthalate (0.15 W/(m·K)) which has similar molecular structure with PEOT, and also higher than that of PEOS (0.32 W/(m·K)) and PEOP (0.38 W/(m·K)). The corresponding heat resistance index (THRI), elasticity modulus, and hardness of PEOT are 174.6°C, 3.6 GPa, and 154.5 MPa, respectively, and also higher than those of PEOS (162.2°C, 1.8 GPa, and 83.4 MPa) and PEOP (171.8°C, 2.3 GPa, and 149.6 MPa).

Enhanced thermal stability and long-term mechanical durability at elevated temperatures of thermotropic liquid crystal polyester/glass fiber composites

We herein report the influences of glass fibers (GFs) on the thermal stability and long-term mechanical performance at elevated temperatures of thermotropic liquid crystal polyester (TLCP) composites for advanced applications in the industrial sectors of automotive, electric/electronics, aerospace, and construction. For this purpose, TLCP-based composites with 10–40 wt% GF loadings are fabricated by facile melt-mixing and injection-molding. The scanning electron microscopy (SEM) images and X-ray diffraction patterns demonstrate that the GFs are dispersed in the TLCP matrix with a microfibrillar structure. The specific interactions between TLCP and GFs in the composites are identified by ATR FT-IR spectroscopic analyses. The thermal degradation temperatures of the composites increase slightly with the increment of GFs with high thermal stability and heat capacity. The long-term mechanical durability of TLCP/GF composites at 150 °C is analyzed by obtaining time-dependent storage modulus master curves based on the stepped isothermal method and time–temperature superposition principle. The dynamic mechanical moduli, activation energy, and long-term mechanical durability are found to be highly enhanced for TLCP composites with higher GF loadings, which is owing to the efficient stress transfer from the TLCP matrix to reinforcing GF fillers via specific interactions at the composite interface.

Fabrication of High Performance PET/TLCP Fibers through the Synergistic Interfacial Enhancement and Compatibilization of Functional 1D and 2D Carbon Nanomaterials

AbstractThe maleic anhydride functionalized graphene oxide (GO‐MA) is fabricated by an efficient and solvent‐free Diels–Alder reaction. Polyethylene terephthalate (PET)/thermotropic liquid crystal polyester (TLCP), PET/TLCP/GO‐MA, PET/TLCP/aminated multi‐walled carbon nanotubes (MWCNTs‐NH2), and PET/TLCP/GO‐MA/MWCNTs‐NH2 composite fibers are systematically melt‐spun. The structure and compatibilizing effects of GO‐MA and MWCNTs‐NH2 on the mechanical, thermal, and crystallization properties of the composite fibers are indicated. The non‐isothermal crystallization kinetics and X‐ray diffraction (XRD) data show that TLCP and nanofillers can change the crystalline morphology of PET. The mechanical properties of the fibers rise with increasing TLCP content. The tensile strength 929 MPa and modulus 17.5 GPa of the fibers with 7 wt% TLCP and 0.25 wt% nanofillers (0.1 wt% GO‐MA and 0.15 wt% MWCNTs‐NH2) are significantly higher than those with 7 wt% TLCP (tensile strength 622 MPa and modulus 16.1 GPa) and even higher than those with 15% TLCP (tensile strength 836 MPa, and modulus 18.0 GPa). When the GO‐MA and MWCNTs‐NH2 co‐exist, the anti‐dripping phenomenon is improved. Therefore, the TLCP, GO, and MWCNTs synergistically strengthens the mechanical properties. This is promising for the industrial fabrication of high‐strength fibers.

Progress of liquid crystal polyester (LCP) for 5G application

With the ever-growing demand for 5G networks and the promise of real-time, mission-critical applications, the advanced antennas with high-bandwidth and highly reliable connectivity are urgently needed. 5G networks primarily operate in two areas of spectrum below 6 GHz (known as sub 6) and millimeter wave, which are much higher than the working frequency of 4G cellular networks, thus the previously used materials and integration techniques need to be updated accordingly. In this sense, liquid crystal polyesters (LCP) have been considered as ideal high performance microwave/millimeter wave (mm-wave) substrate and packing materials due to their outstanding properties. More specifically, the LCP normally exhibit good thermal stability, low water absorption, stable dielectric constant and loss tangent in millimeter wave frequency range, which leads to the increasing research interests of LCP for 5G devices application in both academia and industrial fields. However, the review articles focusing on the chemistry and materials aspects of LCP intended for 5G application are unexpectedly limited. In this article, we will summarize the research progress of LCP materials used in 5G networks in the view of polymer science and engineering. More specifically, the polymerization, chemical structure, aggregated state, properties, modification and processing of typical LCP are reviewed, which would be useful for promoting practical application of the LCP in key devices of 5G networks.

Deformation of Hierarchical Lamellar Structure Formed by a Liquid Crystalline Block Copolymer

AbstractThe deformation of a structure of alternating liquid crystal (LC)/viscous layers upon being stretched along the normal layer is investigated using highly ordered, near‐single‐crystal lamellar fibers of an LC block copolymer. The block copolymer consists of poly(ethyl methacrylate) (PEMA) segments attached to a main‐chain LC polyester at both ends. The LC block segregates from the PEMA block and forms a smectic LC, laying the layers parallel to the interface with PEMA block lamellae to form a hierarchical layered structure. Deformations on stretching the fiber sample are observed by X‐ray scattering measurements. The fiber deformation causes lamellae to dilate and undulate at elongation ratio (λ) &lt; 1.6, wherein PEMA block lamellae are preferentially dilated to tilt lamellar boundaries. In the dilated LC block lamellae, the smectic layers undulate without changing the layer spacing. With further fiber elongation, the lamellae are folded into a chevron rather than dilated, recovering the lamellar spacing.

Functional Coatings on High‐Performance Polymer Fibers for Smart Sensing

AbstractAbove a critical temperature, high‐performance fibers may lose their mechanical properties resulting in catastrophic events of damage when, e.g., used as load‐carrying ropes. Here, a method to functionalize polymer fibers with thermochromic optical coatings that enable signaling of damaging thermal history is introduced. These smart coatings are comprised of an index‐tunable anti‐reflection coating based on chalcogenide phase change materials (PCM). It is demonstrated that the insulator−metal phase transition of these materials can be aligned with the critical deterioration temperature of both polyethylene terephthalate (PET) monofilaments and liquid‐crystal polyester (LCP) yarns by composition tuning. The carefully designed optical system amplifies the change in optical properties of its constituents upon phase change. The thermal and mechanical degradation of these fibers can thus be monitored and displayed by eye.

Synthesis and Properties of Thermotropic Poly(oxybenzoate-co-oxynaphthoate) Copolyester Modified by a Third AB Type Monomer

The synthesis and modification of high performance thermotropic liquid crystal polyesters (TLCP) are still being investigated due to their excellent properties. In this study modification of poly(oxybenzoate-co-oxynaphthoate) (P-HBA/HNA), a random copolymer of 4-hydroxybenzoic acid (HBA) and 6-hydroxy-2-naphthoic acid (HNA), by 5 mol% of one of three AB type monomers (AB type monomers are those who have hydroxy and carboxylic end groups), vanillic acid (VA), 4-hydroxyphenylacetic acid (HPA) and 4-hydroxycinnamic acid (HCA), was conducted. The influence of the AB type third monomer on the liquid crystal properties, melting behavior, thermal stability, microstructure and fiber morphology of the resulting modified terpolyesters was comparatively studied relative to the parent copolymer. When 5 mol% of the HBA units were replaced, the resulting terpolyesters had much lower melting temperatures and could be easily melt processed, while the modified terpolyesters exhibited higher melting and glass transition temperatures when 5 mol% of the HNA units were replaced. Weaker melting peaks and larger melting ranges were observed for the modified terpolyesters, attributed to the existence of nonperiodic layer crystallites caused by the modifiers. The obtained terpolyesters showed good thermal stability and could be melt processed in a broad nematic phase temperature region. The molecular chain packing of the modified terpolyesters was almost destroyed by the third AB type reactants. Fibers prepared from the resulting terpolyesters exhibited well developed fibrillar structure and higher orientation factors, indicating that modification of the P-HBA/HNA by using the AB type monomers to improve its properties would be useful.

Transition of liquid crystal anchoring at the microdomain interface observed for main-chain nematic polyester segments of block copolymers

The microdomain structures and liquid crystal (LC) orientations of ABA triblock copolymers comprising poly(styrene) (PS) A blocks and a main-chain LC polyester B block were examined via small-angle X-ray scattering and electron microscopy in the form of fibrous samples. The LC polyester blocks were segregated from the PS blocks to form a nematic LC in the lamellar microdomains of the copolymers, with the PS volume fraction (φ) ranging from 13 to 38%. As φ decreased, the nematic director was always positioned along the fiber axis, but the microdomain lamellae changed their direction from parallel to perpendicular with respect to the fiber axis and began to adopt a zigzag configuration. These lamellar orientations were attributed to the main-chain nematic LC segments lying along the microdomain interface but extending perpendicularly to the interface as the occupying interface area was reduced. The lamellar microdomains parallel to the nematic director increased the LC and PS lamellar thicknesses reversibly by 48 and 16%, respectively, at the same time as the isotropization of the nematic LC. Such changes in lamellar thickness suggest that both the PS and LC segments were elongated along the direction of the LC orientation.

液晶ポリエステル繊維を主体としたハイブリットFRPの特性 : ハイブリットFRPの特性と応用(2)(第35回研究発表大会)

液晶ポリエステル繊維を主体としたハイブリットFRPの特性 : ハイブリットFRPの特性と応用(2)(第35回研究発表大会)

Thermally Reversible Distortion Observed for Triblock Copolymers Comprising Main-Chain Liquid Crystal Polyesters Attached to Photo-Cross-Linked Cinnamate Segments at Both Ends

ABA triblock B5 Cin copolymers were prepared by attaching photoreactive poly(2-cinnamoyloxyethyl methacrylate) (PCEMA) segments to both ends of main-chain smectic BB-5(3-Me) polyesters. The copolymers with PCEMA volume fraction (φ) ranging from 23% to 50% formed lamellar microdomains, and the BB-5(3-Me) block formed smectic layers parallel to the lamellae. When the B5 Cin melt was drawn into film and annealed at a liquid crystal (LC) temperature of BB-5(3-Me), the lamellae and smectic layers lay perpendicular to the longitudinal direction. The PCEMA block in the monodomain films was cross-linked by UV irradiation leading to 20% conversion. When heated, the cross-linked films with φ > 37% contracted reversibly on the isotropization of the LC segment, coinciding with the reversible decrease in the lamellar spacing (D). The film elongated on the liquid crystallization by a factor which increased from 1.07 to 1.24 with decreasing φ.

Combined effects of kink bands and hygrothermal conditioning on tensile strength of polyarylate liquid crystal co-polymer and aramid fibers

Translation of tensile properties from high-performance fibers to end-use fabrics is sensitive to weaving-induced filament defects and environmental exposure. In this effort, isolated and combined effects of hygrothermal exposure and curvature-induced kink bands on tensile strength of Vectran™ HT (polyarylate liquid crystal polyester fiber) and Kevlar® KM2 are studied. Hygrothermal conditioning was conducted at temperatures ranging from 40℃ to 100℃ in water for 30 days. Curvature-induced defects were created by wrapping tows around stainless steel rods of different diameters (0.25 mm to 5 mm) to create kink bands. Combined effects were evaluated by conditioning tows with kink bands at 100℃ for 30 days. All conditioned samples were dried and tested at room temperature. Hygrothermal aging showed that tensile properties for Vectran fibers were not appreciably affected below 100℃ (∼12% reduction), while KM2 fibers dropped continuously with increasing temperatures (∼48% at 100℃). The influence of curvature on kink band density was established for each fiber type. The isolated effect of kink band density on residual strength was approximately 15% for both Vectran 1670/600 and KM2-600. Combined effects of curvature-induced kink bands followed by hygrothermal exposure showed significant reductions in tenacity up to ∼96% for KM2 and 60% for Vectran HT1670/600. Inspection of the microstructure within the kink bands reveals extensive micro-cracking and fibril failure due to accelerated moisture ingress.

Self-Assembly of Flexible–Semiflexible–Flexible Triblock Copolymers

The self-assembly of ABA triblock copolymers comprising flexible amorphous poly(ethyl methacrylate) (PEMA, A block) and semiflexible liquid crystal (LC) polyester (B block) was investigated for amorphous block volume fractions (φ) ranging from 20% to 80%. Two copolymer series with different LC block molecular weights (Mn,LC) were examined. At φ < 55%, block copolymers with Mn,LC = 11 600 formed lamellar microdomains in which LC segments mostly extended along the lamella normal but folded to fit in the lamellae. When φ was augmented, the LC segment fold (Nfold) increased to enhance the interface between the LC and amorphous segments and counterbalanced the increase in amorphous lamella thickness by reducing the LC lamella thickness. When φ > 68%, the LC lamellae were divided into cubes, transforming into spheres in the PEMA matrix. When Mn,LC decreased to 6300, the copolymers showed similar morphology. However, the lamellae adopted zigzag configurations showing a greater tilting angle between the lamella normal to the LC chain axis with increasing φ. Thus, the LC and PEMA segments enhanced their interface by mutually sliding along the chain axis instead of increasing Nfold.