Crystal Polymer Research Articles

Morphology reconstruction from experimental small-angle x-ray scattering patterns by physics-aware neural network

In this work, we developed a new methodology that can reconstruct the morphology from experimental small-angle x-ray scattering (SAXS) patterns directly without modeling by using a physics-aware neural network, SAXSNN. By incorporating the scattering physics of x rays into the network, SAXSNN could be trained to capture the complex mapping between the SAXS patterns in reciprocal space and the corresponding morphologies in real space in an unsupervised way. We demonstrated the performance of SAXSNN on the experimental SAXS patterns of semicrystalline and amorphous polymers, i.e., hard-elastic isotactic polypropylene (iPP) films and plasticized poly(vinyl butyral) (PVB). The morphologies reconstructed by SAXSNN are well consistent with our existing knowledge of the morphology of iPP films and PVB. The developed methodology here allows us to rapidly predict the morphologies for any given SAXS pattern without any in-prior phase information and, thus, provides an intuitive understanding of the microstructures of the measured samples. A real-time feedback of the morphologies of measured samples to SAXS beamline users at modern synchrotron radiation light sources will be feasible in the near future.

Systematic investigation of charge transport and thermoelectric properties in semicrystalline polymers: electrochemical doping effects on doping level and temperature dependence using one sample

Abstract We developed a system to measure the temperature dependence of the Seebeck coefficient (S) and electrical conductivity of conducting polymers with controlled doping levels, using an electrolyte-gated transistor structure, all based on a single sample. In the semicrystalline polymer poly[2,5-bis(3-alkylthiophen-2-yl)thieno[3,2-b]thiophene], S shows clear temperature dependence, attributed to hopping-like transport in the low-doped state. In contrast, metal-like behavior dominates in the highly-doped state. However, in the low-temperature region of the highly-doped state, an unusual temperature dependence of S likely arises from the coexistence of localized and delocalized transport processes. This is further confirmed by magnetoconductance measurements down to 80 mK.

Binary Phase Diagrams of Coordination Polymers with Eutectic Behaviors.

We demonstrated the construction of binary phase diagrams of coordination polymer crystals by using their reversible solid-liquid transition (melting and crystallization) behaviors. Three types of binary phase diagrams of Ag+-based coordination polymers were made and the origins of each diagram formation were investigated. All diagrams showed eutectic phenomena induced by ligand exchange reactions at the interface of the two constituents. Solid solution formation was observed when we used two crystals with similar structures and coordination geometries, and the reaction was driven by both the anion and ligand exchange processes. The optimal binary compounds found in the phase diagrams were applicable as a latent heat storage material working at 100 °C with high energy recovery efficiency, stability in phase-transition cycles, and large hysteresis of melting/crystallization.

Physics-Informed Data-Driven Discovery of Polymer Crystals with High Thermal Conductivity

Physics-Informed Data-Driven Discovery of Polymer Crystals with High Thermal Conductivity

Small-angle Scattering Mechanisms in Semicrystalline Polymers

Small-angle Scattering Mechanisms in Semicrystalline Polymers

Advanced Avrami Formula and its Application to Describing the Isothermal Crystallisation of Polymers

Advanced Avrami Formula and its Application to Describing the Isothermal Crystallisation of Polymers

Development of hot melt extruded Polycaprolactone (PCL) matrices for an oral ultra-long-lasting delivery of Galantamine for Alzheimer’s disease therapy

Galantamine Hydrobromide (GAL) is a tertiary alkaloid, acting as a competitive and reversible cholinesterase inhibitor. It is indicated for the symptomatic treatment of patients from mild to moderate dementia level of the Alzheimer’s disease (AD) type. For treatment of mild to moderate AD, GAL is generally combined with other drugs. The purpose of this work was development and characterization of hot melt extruded (HME) matrices based on polycaprolactone (PCL) for GAL oral ultra-long-lasting delivery. PCL is biodegradable polymer, biocompatibility, water-insoluble and excellent for HME process. From HME drug and polymer mixtures arms from 1 % up to 50 wt-% of GAL were obtained. The raw materials and the as-obtained HME arms were characterized by particle size distribution (PSD), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), wide angle x-ray scattering (WAXS) and dissolution test. Our findings showed that GAL possesses crystalline form I polymorphic, it is thermodynamically stable, and remains their particle and crystalline form even after HME process. Crystallization temperature of PCL increases with GAL content, indicating strong heterogeneous nucleating effect of drug on polymer crystallization process. SEM morphological analysis indicates continuous polymeric phase on surface. However, higher amounts of GAL (50/50 wt-%) presented clusters and heterogeneity, especially in extruded cross-section. It may have influenced the drug release property, decreasing the sustained release ability, due to the transport of medium molecules through the bulk extrudates by GAL soluble clusters. The diffractograms (WAXS) showed patterns peaks of GAL and PCL, indicating that GAL remains its crystalline structure and PCL recrystallized. In the dissolution test, PCL/GAL 80/20 and 90/10 achieved 100% with over seven days and profiles that can be tuned by varying GAL concentration. Finally, we demonstrate the feasibility of using HME process based on the mixture of PCL and GAL as proposals for oral therapies for conditions of AD. This is the first report showing PCL-GAL polymer matrices that achieves several-days drug release.

Crystalsomes via confined polymer crystallization in nanoemulsions

Crystalsomes via confined polymer crystallization in nanoemulsions

On the mechanical, thermal, rheological, and processing properties of ultra-high molecular weight polypropylene

Ultra-high molecular weight polypropylene (UHMWPP), a semicrystalline polymer, presents processing challenges due to its intricate crystalline and amorphous components, interconnected by molecular entanglements and tie molecules. These entanglements are critical for transferring stress during deformation and mechanical performance. Processing UHMWPP using traditional methods is difficult due to its high viscosity and entanglement density. In this study, we successfully fabricated UHMWPP using gel-casting, a well-established technique for high molecular weight polymers. Comprehensive evaluations revealed enhanced mechanical, thermal, and rheological properties, including improved mechanical strength and crystallization properties. Our findings establish gel-casting as an effective approach for processing UHMWPP, enabling its broader industrial applications in high-performance materials.

Influence of Polystyrene Molecular Weight on Semiconductor Crystallization, Morphology, and Mobility

The morphological characteristics of organic semiconductors significantly impact their performance in many applications of organic electronics. A list of challenges such as dendritic crystal formation, thermal cracks, grain boundaries, and mobility variations must be addressed to optimize their efficiency and stability. This paper provides an in-depth overview of how different polymer additives (conjugated, semicrystalline, and amorphous polymers) influence the crystallization, morphology and mobility of some well-studied organic semiconductors. Conjugated polymers enhance molecular alignment and crystallinity, leading to distinct crystalline structures and improved charge transport properties. Semicrystalline polymers offer in-situ crystallization control, which improves film morphology and increases crystallinity and mobility. Amorphous polymers help minimize misalignment and promote parallel orientation of organic crystals, which is critical for effective charge transport. Special attention is given to polystyrene (PS) as a representative additive in this review, which highlights the significant effects of its molecular weight (Mw) on film morphology and charge transport properties. In particular, low-Mw PS (less than 20k) typically results in smaller, more uniform crystals, and enhances both charge transport and interface quality. Medium-Mw PS (20k to 250k) balances film stability and crystallinity, with moderate improvements in both crystal size and mobility. High-Mw PS (greater than 250k) promotes larger crystalline domains, better long-range order, and more pronounced improvement in charge transport, although it may introduce challenges such as increased phase separation and reduced solubility. This comprehensive analysis underscores the decisive role of polymer additives in optimizing the morphology of organic semiconductors and maximizing their charge transport for next-generation organic electronic applications.

Effects of Additional Flexible and Rigid Structure on BDT-BDD Terpolymer and the Performance of Organic Solar Cells.

In organic solar cells, the aggregation and crystallization of polymers are significant for bulk heterojunction. Blending with acceptor materials, polymer donor materials can adjust their aggregation by the movement of the chain segments. In this paper, the unfused structures based on thiophene and carbazole are respectively designed and introduced into the donor-acceptor copolymer donor materials to investigate the influence of flexible and rigid structures on polymer-aggregation leading photoelectric performance. The material and quantum chemical property investigations show that the selection and design of the blocks are important for the properties of the terpolymers, and the resulting polymer:Y6 devices achieve improvements in performance from 13.85% to 15.66% (especially for fill factors from 63.37% up to 69.81%). This result contributes to designing and optimizing efficient polymers.

Friction Performance of Three-Dimension Printed PEEK for Journal Bearing Application Under Grease Lubrication

Abstract Additive manufacturing revolutionizes component and part creation, offering unmatched flexibility and reducing production time. This innovation, especially significant with semicrystalline polymers like polyetheretherketone (PEEK) at high temperatures, expands applications, including sleeves and bushes. PEEK's mechanical and tribological properties make it an attractive long-term metal replacement. However, the 3D printed PEEK surface is pivotal, and the surface structure depends on infill density, which influences its response to sliding conditions, such as speed, load, and test duration. The PEEK structure's surface patterns facilitate lubricant accommodation, particularly during boundary lubrication tests, affecting the formation of a transfer layer. Surface properties directly impact friction in 3D printed PEEK against the counterbody. Lubrication decreases friction coefficients compared to dry conditions. Wear tests show that 3D printed PEEK parts outperform extruded rod samples, displaying superior wear resistance. Surface texture and properties directly affect contact characteristics and lubricant storage. In journal bearings, varying infill percentages create surface voids, efficiently accommodating polyalphaolefin (PAO)-based grease in PEEK-based applications where oil is not preferred for sliding operations.

Boosting Thermoelectric Performance of Semicrystalline Conducting Polymers by Simply Adding Nucleating Agent.

Controlling the microstructure of semiconducting polymers is critical for optimizing thermoelectric performance, yet remains challenging, requiring complex processing techniques like alignment. In this study, a straightforward strategy is introduced to enhance the thermoelectric properties of semi-crystalline polymer films by incorporating minimal amounts of nucleating agents, a method widely used in traditional polymer industries. By blending less than 1 wt% of N,N'-(1,4-phenyl)diisonicotinamide (PDA) into poly(2,5-bis(3-alkylthiophen-2-yl)thieno[3,2-b]thiophene) (PBTTT-C14), controlled modulation of crystallization behavior is achieved, resulting in reduced structural disorder and enhanced charge carrier mobility. Systematic investigations reveal that an optimal PDA loading of 0.9 wt% increases the crystallization degree by 45% compared to pristine PBTTT-C14 films. Under these optimized conditions, the PDA-modified PBTTT-C14 films exhibit a maximum electrical conductivity of 1,894Scm-1 and a maximum power factor of 176µWm-1K-2, showing improvements of 96% and 433%, respectively, over doped pristine PBTTT-C14 films. These gains are attributed to the synergistic effects of polymer chain extension and reduced grain boundary resistance, which collectively enhance charge transport efficiency. Additionally, ion exchange doping is found to maintain a high charge carrier concentration while preserving the crystallinity introduced by PDA, paving the way for advanced thermoelectric materials and next-generation polymer-based electronics.

Direct Observation of Early-Stage Polymer Crystallization Driven by Surface Wrinkling and Compressive Stress in Thin Films

Direct Observation of Early-Stage Polymer Crystallization Driven by Surface Wrinkling and Compressive Stress in Thin Films

Temperature and Deformation-Induced Changes in the Mechanical Properties of the Amorphous Regions of Semicrystalline Polypropylene.

This work is focused on the impact of temperature and deformation on the mechanical properties, specifically the elastic modulus (Ea) of the amorphous regions in semicrystalline polymers, using polypropylene as a case study. It has been shown that increasing temperature results in an Ea decrease due to the enhanced mobility of polymer chains, triggered by the activation of α relaxation processes within the crystalline component. Consequently, rising temperature reduces the "stiffening" effect of the crystalline regions on the interlamellar layers. Temperature decrease close to the glass transition causes a significant increase in the Ea value, reaching nearly 70 MPa. Next, the effects of crystalline/amorphous component orientation and undisturbed crystallite length on Ea were examined in materials deformed using a channel die at various compression ratios. At low compression ratios, Ea decreases nearly 4-fold, primarily due to the fragmentation of lamellar crystals in the absence of, or with relatively low, orientation of the crystalline and amorphous components. Conversely, at higher compression ratios, with minimal crystal fragmentation, increased orientation of both crystalline and amorphous regions along the deformation direction (Ea measurement direction) leads to a substantial increase in Ea. Ultimately, the material with the highest used compression ratio exhibited an Ea value approximately 20% higher than that of the undeformed material.

Simultaneous Toughening and Strengthening of Ductile Polymer by Rigid Polymeric Fillers: The Role of Interfacial Entanglement.

The modification of thermoplastic polymers is frequently impeded by the inherent contradiction between their toughness and strength. In this study, an effective strategy to significantly improve the mechanical properties of ductile polymers by simply adding a complimentary rigid polymer is introduced. This work uses a semi-crystalline polymer aliphatic polyketone (POK) as the matrix material and a small quantity of polymethyl methacrylate (PMMA) as the rigid polymer, through establishing molecular chain entanglements at the interface to produce POK/PMMA blends with exceptional mechanical property. The experimental study shows that PMMA as a small island phase is homogeneously dispersed in the POK matrix, while the interfacial adhesion between the POK matrix and PMMA island is enhanced by the high-density molecular chain entanglement between PMMA and the POK matrix. The strong entanglements and high concentration of PMMA domains promote uniform crazes and overall shear yielding. As a result, the POK/PMMA blend exhibits exceptional mechanical properties with notched impact strength, elongation at break, tensile strength, and Young's modulus, of 20kJm-2, 326%, 60 and 2185MPa, respectively. A universal approach is further suggested for enhancing the toughness and strength of ductile polymers using a complimentary rigid polymer.

Improvement of the Conductive Ability of Polymer Electrolytes

In current applied research, traditional electrolytes face significant challenges. The emergence and application of polymer electrolytes provide effective solutions to these problems. This paper will introduce the types and characteristics of polymer electrolytes based on three aspects. The star-shaped compound based on PEGMA, i.e., poly(ethylene glycol) methacrylate, can significantly enhance the mechanical and electrical properties of polymer electrolytes; the gel electrolyte prepared by compounding highly polar β-polyvinylidene fluoride (β-PVDF) with nylon 6 shows significant application potential in improving ion conduction efficiency and enhancing battery safety. Brush-shaped polymers have good performance in avoiding the crystallization of linear polymers and inhibiting the growth of lithium dendrites and improving mechanical strength. These three types of polymer electrolytes each have their characteristics and good application prospects. Still, they all face problems such as high cost and difficulties in industrialization at the present stage and need further development to better benefit human society. This paper aims to provide those who want to explore and do some decent research on this topic with some basic information as well as fundamental advice.

Permanent Deformation of Thermoplastic Polyurethane in the Solid‐State Rolling Process

The findings suggest that rolling is a potentially effective technique for commercial applications in industries requiring high‐performance polymer films. The solid‐state rolling process is well‐established for semicrystalline and amorphous polymers, but its application to segmented, two‐phase polymers like thermoplastic polyurethane (TPU) which features physically cross‐linked systems and excellent physical and mechanical properties, remains underexplored. This study aims to investigate the rolling of TPU under various conditions to address viscous relaxation and achieve maximum thickness reduction, producing thin sheets. The rolling characteristics were assessed by measuring the thickness changes of rolled specimens of two TPUs with different hard phase fractions, alongside thermoset polyurethane (PUR) with chemical cross‐linking for comparative analysis. The results showed that the TPUs exhibited little plastic deformation at room temperature. The cold rolling test, conducted at a rolling speed of 0.5 m min−1 with a nominal reduction of 85%, indicated that the permanent reduction ratio was less than 35% for both TPUs. However, when the rolling speed was increased to 3 m min−1, the permanent reduction ratio increased to 67% and 60% for TPU ShA90 and TPU ShA85, respectively. This result indicates that at high rolling speeds, the thermal condition tends to change from isotherm to adiabatic in the rolling test. The maximum reduction ratio of 70% was achieved at a nominal reduction of 85% for TPU ShA90 at higher rolling temperatures and speeds.

Conjugated core-shell bottlebrush polymers that exhibit crystallization-driven self-assembly.

Bottlebrush polymers are complex architectures with densely grafted polymer side chains along polymeric backbones. The dense and conformationally extended chains in bottlebrush polymers give rise to unique properties, including low chain entanglement, low critical aggregation concentrations, and elastomeric properties in the bulk phase. Conjugated polymers have garnered attention as lightweight, processible, and flexible semi-conducting materials. They are promising candidates in electronic devices and sensors, but their optoelectronic properties depend on adequate polymer ordering, π-π interactions, and crystallization. Crystallization-driven self-assembly of conjugated polymers has become a prominent method to optimize properties including band energies, redox potentials, and exciton diffusion and transport. Much progress has been made in controlled block copolymer self-assembly, but despite their promising properties, reports of conjugated bottlebrushes have been limited, and their self-assembly is relatively unexplored. For the first time, we report the synthesis of conjugated core-shell bottlebrush polymers. These materials contain poly(3-hexylthiophene) (P3HT) and poly(ethylene glycol) (PEG) in either core or shell position. We demonstrate that the use of P3HT as a crystallizable conjugated polymer and PEG as a colloidally stabilizing and disaggregating block facilitates their self-assembly into a number of unique crystalline morphologies with longer conjugation lengths and lower exciton bandwidths relative to analogous diblock copolymers. These include intramolecularly self-assembled segregated bottlebrush polymers, short nanofibers formed by end-on-end stacking of bottlebrush molecules, extremely long >20 μm nanofibers formed exclusively by end-on-end stacking, and >15 μm nanoribbons formed from both end-on-end and side-by-side stacking of bottlebrush polymers.

Transformation of semicrystalline polymer mechanics by cyclic polymers

Cyclic polymers, lacking chain ends and featuring unique topological constraints, offer distinctive mechanical behaviors.