Strong Phase Separation Research Articles

Design of Fluorinated Elastomeric Electrolyte for Solid-State Lithium Metal Batteries Operating at Low Temperature and High Voltage.

This work demonstrates the low-temperature operation of solid-state lithium metal batteries (LMBs) through the development of a fluorinated and plastic-crystal-embedded elastomeric electrolyte (F-PCEE). The F-PCEE is formed via polymerization-induced phase separation between the polymer matrix and plastic crystal phase, offering a high mechanical strain (≈300%) and ionic conductivity (≈0.23 mS cm-1) at -10°C. Notably, strong phase separation between two phases leads to the selective distribution of lithium (Li) salts within the plastic crystal phase, enabling superior elasticity and high ionic conductivity at low temperatures. The F-PCEE in a Li/LiNi0.8Co0.1Mn0.1O2 full cell maintains 74.4% and 42.5% of discharge capacity at -10°C and -20°C, respectively, compared to that at 25°C. Furthermore, the full cell exhibits 85.3% capacity retention after 150 cycles at -10°C and a high cut-off voltage of 4.5V, representing one of the highest cycling performances among the reported solid polymer electrolytes for low-temperature LMBs. This work attributes the prolonged cycling lifetime of F-PCEE at -10°C to the great mechanical robustness to suppress the Li-dendrite growth and ability to form superior LiF-rich interphases. This study establishes the design strategies of elastomeric electrolytes for developing solid-state LMBs operating at low temperatures and high voltages.

Polyetheramine‐Type Semi‐Biobased Long‐Chain Polyamide 1210 Elastomer: Synthesis, Structure, and Unique Thermal Behavior

AbstractBiobased thermoplastic polyamide elastomers (TPAEs) have received increasing attention in both academia and industry. Here, a series of semi‐biobased long‐chain TPAEs are successfully synthesized via one‐step melt polymerization, employing polyamide 1210 (PA1210) and polyetheramines (PEAs) as hard and soft segments, respectively. The prepared TPAEs demonstrate excellent mechanical properties, energy dissipation capabilities, low density, good damping, high resilience, and low melting temperature. More interestingly, the properties of the TPAEs can be customized by adjusting the content and molecular weight of PEA. By varying the molecular weights of the PEAs, two different thermal behaviors can be observed in the prepared TPAEs. Specifically, PEA with low molecular weight has good compatibility with PA1210, leading to an increase in the conformation of the crystalline region and a significant decrease in melting temperature. Meanwhile, high molecular weight PEA causes strong phase separation with PA1210, leading to limited crystalline regions and inadequate physical cross‐linking, further resulting in suboptimal mechanical properties. This work provides new insights into the design and preparation of PEA‐type biobased long‐chain TPAEs.

Synergistic formulation approach for developing pea protein and guar gum enriched olive oil-in-water emulsion gels as solid fat substitutes: Formulation optimization, characterization, and molecular simulation

This study aimed to optimize the formulation of olive oil-in-water (O/W) emulsion gels by incorporating Pea Protein (PP) and Guar Gum (GG) as alternative options for solid fats. The optimum rheological (consistency index, apparent viscosity, recovery) and texture (firmness) properties of the emulsion gels were obtained using a mixture of 2 % PP, 1 % GG, 60 % Olive Oil (OO), and 37 % Water (W). The blend of PP2/GG1 showed the highest results for recovery and firmness, 111.27 % and 33.89 g, respectively. PP/GG blend emulsion gels exhibited higher absolute ζ-potential values, ranging between −72.3 and −77.4 mV. The polydispersity index (PDI) ranged from 0.185 to 0.535, with the most uniform distributions found in the PP/GG blend emulsion gels. Strong phase separation resistance indicated strong stability of PP-GG complex emulsion gels. Higher PP concentrations decreased emulsion oxidation. FTIR and XRD research showed that PP and GG interact strongly, indicating good compatibility. The free binding energy of the most stable configuration of the molecules was −6.8 kcal mol−1, indicating a high affinity. PP interacted with GG through 9 amino acid residues, with notable residues being Asp 224, Thr 235, Ala 332, Ile 334, and Arg 336, and their respective interaction distances ranged between 2.69 Å and 3.87 Å.

High C-Rate Dynamic Lithium (de)Insertion Pathway Investigated via Synchrotron-Based Operando XRD and Operando Scanning x-Ray Microscopy

Lithium-ion insertion kinetics fundamentally hinges upon phase transformation behavior during (dis)charging and understanding the rate-dependent kinetics is crucial for the development of high-power batteries. At high c-rates, kinetic hysteresis is amplified and phase evolution becomes heterogeneous and unpredictable. Specifically, discharge becomes more sluggish than charging of most battery electrodes including LiNixMnyCozO2 (NMC) and LiFePO4 (LFP). Here, we developed an operando soft x-ray microscopy to simultaneously observe surface charge transfer and bulk lithium diffusion in facet-controlled individual battery particles over a wide range of cycling rates (0.01 – 10C). Our result unambiguously reveals that dynamic asymmetry between fast charging and discharging originates from auto-inhibitory Li-rich and autocatalytic Li-poor surface domains, respectively. In addition, we developed synchrotron-based operando fast XRD to track phase evolution during fast cycling. We directly observed that sluggish Li diffusion at high Li content induces different phase transformations during charging and discharging, with strong phase separation and homogeneous phase transformation during charging and discharging, respectively. Moreover, by electrochemically manipulating the lithium-ion concentration distribution within NCM particles, phase separation pathway could be redirected to solid-solution kinetics even at 7 C-rate. Our work lays the groundwork for developing high-power applications and ultrafast charging protocols Figure 1

The In Situ Optimization of Spinterface in Polymer Spin Valve by Electronic Phase Separated Oxides.

Tailoring the interface between organic semiconductor (OSC) and ferromagnetic (FM) electrodes, that is, the spinterface, offers a promising way to manipulate and optimize the magnetoresistance (MR) ratio of the organic spin valve (OSV) devices. However, the non-destructive in situ regulation method of spinterface is seldom reported, limiting its theoretical research and further application in organic spintronics. (La2/3 Pr1/3 )5/8 Ca3/8 MnO3 (LPCMO), a recently developed FM material, exhibits a strong electronic phase separation (EPS) property, and can be employed as an effective in situ spinterface adjuster. Herein, we fabricated a LPCMO-based polymer spin valve with a vertical configuration of LPCMO/poly(3-hexylthiophene-2,5-diyl) (P3HT)/Co, and emphasized the important role of LPCMO/P3HT spinterface in MR regulation. A unique competitive spin-scattering mechanism generated by the EPS characteristics of LPCMO inside the polymer spin valve was discovered by abstracting the anomalous non-monotonic MR value as a function of pre-set magnetic field (Bpre ) and temperature (T). Particularly, a record-high MR ratio of 93% was achieved in polymer spin valves under optimal conditions. These findings highlight the importance of interdisciplinary research between organic spintronics and EPS oxides and offer a novel scenario for multi-level storage via spinterface manipulation.

Imparting High Conductivity to 3D Printed PEDOT:PSS

Complex 3D geometry and high conductivity have generally been mutually exclusive characteristics for conducting polymers. For instance, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), a benchmark conducting polymer, typically exhibits conductivity 1 to 2 orders of magnitude lower in 3D-printed forms compared to 2D-processed thin films, due to its sensitivity to processing conditions. Here, we investigate the main causes of this reduced conductivity, which are found to be (1) the ink formulation strategy and (2) the strong lateral phase separation of the printed filaments. Processing approaches that overcome these factors have produced significant conductivity enhancement to 1200 S/cm, higher than the typical 2D-processed PEDOT:PSS. Our study also unveils a set of guiding principles for optimizing the conductivity of direct ink writing (DIW)-printed PEDOT:PSS, including printing orientation, print bed temperature, and nozzle diameter. With the combination of high conductivity and 3D geometric freedom, potential applications such as omnidirectionally deformable LED devices with strain-independent electrical behavior and bespoke electronics that replicate the shape of human body parts have been demonstrated.

Mesoscale Simulation Based on the Dynamic Mean-Field Density Functional Method on Block-Copolymeric Ionomers for Polymer Electrolyte Membranes.

Block copolymers generally have peculiar morphological characteristics, such as strong phase separation. They have been actively applied to polymer electrolyte membranes for proton exchange membrane fuel cells (PEMFCs) to obtain well-defined hydrophilic regions and water channels as a proton pathway. Although molecular simulation tools are advantageous to investigate the mechanism of water channel formation based on the chemical structure and property relationships, classical molecular dynamics simulation has limitations regarding the model size and time scale, and these issues need to be addressed. In this study, we investigated the morphology of sulfonated block copolymers synthesized for PEM applications using a mesoscale simulation based on the dynamic mean-field density functional method, widely applied to investigate macroscopic systems such as polymer blends, micelles, and multi-block/grafting copolymers. Despite the similar solubility parameters of the monomers in our block-copolymer models, very different morphologies in our 3D mesoscale models were obtained. The model with sulfonated monomers, in which the number of sulfonic acid groups is twice that of the other model, showed better phase separation and water channel formation, despite the short length of its hydrophilic block. In conclusion, this unexpected behavior indicates that the role of water molecules is important in making PEM mesoscale models well-equilibrated in the mesoscale simulation, which results in the strong phase separation between hydrophilic and hydrophobic regions and the ensuing well-defined water channel. PEM synthesis supports the conclusion that using the sulfonated monomers with a high sulfonation degree (32.5 mS/cm) will be more effective than using the long hydrophilic block with a low sulfonation degree (25.2 mS/cm).

Three-Component Bolaform Giant Surfactants Forming Lamellar Nanopatterns with Sub-5 nm Feature Sizes

Nanopatterns with a sub-5 nm line width are of great interest due to their potential applications in nanotechnology. Herein, we report the design and synthesis of three-component bolaform giant surfactants that can assemble into three-phase-four-layer lamellar (LAM3) structures with sub-5 nm feature sizes. These samples consist of central linear polystyrene (PS) chains with oligodimethylsiloxane-functionalized polyhedral oligomeric silsesquioxane (SiPOSS) at one end and perfluoroalkyl-functionalized POSS (FPOSS) at the other end. Phase separation occurs among three mutually incompatible components, leading to LAM3 structures with relatively sharp interfaces and d-spacings of 12–19 nm. While the lamellar periodicity can be facilely tuned by changing the chain length of PS, the pitch widths of the POSS domains remain largely constant. Energy-dispersive X-ray spectroscopy (EDS) and electron energy loss spectroscopy (EELS) were used to analyze the elemental distribution of the LAM3 structures. After oxygen plasma treatment, the morphology converts into a hierarchical lamellar structure with extremely small Si-rich layers (∼2 nm in thickness). This work suggests that these bolaform giant surfactants are versatile counterparts of traditional triblock copolymers capable of undergoing rapid and strong phase separation at relatively low molecular weights toward unconventional nanostructures with small feature sizes.

Competition effect of solid-state stretching induced orientation and phase separation on stereocomplex crystallization of PLLA/PDLA during annealing

Benefiting from its superior thermal and mechanical properties, the stereocomplex crystal (SC) of PLLA/PDLA is catching increasing interest. In this work, a systematic investigation was performed to reveal the effect of solid-state stretching on the formation of SC during annealing. Results show that as the stretching temperature was close to the glass transition temperature (Ts = 60 °C), the polymer chains orientation was increased gradually with draw ratio (λ). As a result, the crystallization induction time (t0) was shortened, the growth rate (Gr) of SC was enlarged, and the crystallinity of SC (XSC) was elevated as a result of orientation-induced crystallization. Whereas, the saturation of t0, Gr, and XSC appeared quickly when λ reached 2.7, although the orientation of polymer chains continued to increase. The reason is that in addition to orientation, strong phase separation between PLLA and PDLA was also triggered therein. The phase separation prohibited greatly the crystallization of SC due to a long time would be needed for PLLA or PDLA chains to diffuse to a distance close enough to activate the hydrogen-bonding interaction, which is the prerequisite of SC crystallization. When the stretching temperature was elevated to 75 °C, the phase separation became much weaker. So XSC was higher compared to that of the blend stretched at 60 °C to the same λ. Moreover, in the annealing temperature from 180 °C–190 °C, t0 was much smaller for the blend stretched at 75 °C since the crystallization of SC in this temperature range is a diffusion-controlled process.

Biodegradable and active zein-gelatin-based electrospun mats and solvent-cast films incorporating sage extract: Formulation and comparative characterization

This study aimed to develop active, biodegradable materials for food packaging by incorporating sage extract (SE) within a zein-gelatin blend by electrospinning and solvent casting. The fabrication techniques, SE incorporation, and its content (5, 10% w/w) determined the materials’ properties. Electrospinning produced 0.36–0.53 mm thick, non-transparent fibrous mats (mean fiber diameter 1.12–1.36 µm). Solvent casting generated 0.34–0.41 mm thick, transparent continuous films. The analysis indicated the constituents’ compatibility, homogenous dispersion, and efficient SE incorporation without strong chemical interactions and phase separation. The solvent-cast films presented more ordered structures, higher mechanical resistance, elongation, and water vapor barrier performance than the electrospun mats. The SE-incorporating formulations showed phenolics’ delivery ability to food simulants influenced by structure, SE content, and media polarity. The electrospun mats expressed higher DPPH• radicals’ inhibition, while the solvent-cast films showed stronger Staphylococcus aureus and Escherichia coli growth inhibition, increased by SE incorporation. All formulations showed rapid complete bio-disintegration in compost (18–25 days).

Organic N‐type Dopants with a Phenyl Tertiary Carbon Structure: Molecular Structure and Doping Properties

AbstractDoping is an effective method to improve the electrical properties of organic semiconductors or insulators. However, current progress in organic n‐doping is limited relative to pdoping. Benzimidazole derivatives are representative organic n‐type dopants that have been widely applied, e. g., 1,3‐dimethyl‐2‐phenyl‐2,3‐dihydro‐1H‐benzo [d] imidazole (DMBI); its active unit is the phenyl tertiary carbon structure. Here, we designed and synthesized 11 small organic molecules with different phenyl tertiary carbon structures that were constituted by different heteroatoms (O, S, N) and several tertiary carbons to adjust the n‐doping performance. These molecules were then applied to dope polyalkylfluorene‐based organic semiconductor PFN to get a composite solid film. After optimization, the electrical conductivities of the prepared films were all enhanced by about three orders of magnitude. After experimentation and analysis, we confirmed that those dopants can effectively transfer their electrons to the host material. In addition, introducing the N atom to tertiary carbon and conjugating heteroatom with an aromatic ring improved its doping efficiency, but strong phase separation performance may result in limits on further heightening of conductivity. Therefore, these results are important for research into organic n‐type dopants.

Ionic Switches with Positive Temperature Coefficient Enabled by Phase Separation within Hydrogel Electrolytes.

Ionic switches with a positive temperature coefficient (PTC) effect are highly desirable in the fabrication of smart electrolytes for the safety protection of electrochemical energy devices. However, most of them encounter liquid leaking or volume shrinking problems, limiting their long-term and stable operations. Herein, a PTC-type ionic switch is introduced based on a poly(acrylic acid) (PAA) hydrogel soaked by calcium acetate (CaAc), with a resistance change of six times in maximum between the homogeneous and phase separated state. The PTC effect is owing to the strong phase separation upon heating where the ion transport is restricted. Such a hydrogel-based PTC-type ionic switch is in the solid state and isochoric during phase separation without leaking or shrinking issues. The influence of different CaAc soaking concentrations is investigated. A simplified model consisting of interconnected ion channels is proposed based on microstructure analysis. A smart supercapacitor is successfully demonstrated by this PTC ionic switch with a safety protection ability. The research here would provide a new pathway for the design and development of PTC-type ionic switches in the safety protection of electrochemical energy storage devices.

Exploration of the co-structuring and stabilising role of flaxseed gum in whey protein isolate based cryo-hydrogels

In the present work, the structuring and stabilising potential of flaxseed gum (FG) in whey protein isolate (WPI) cryo-hydrogels was investigated. The FG presence (0.1–1% wt.) in the heat-treated WPI dispersions (10% wt.) induced strong segregative phase separation phenomena, which were associated with a depletion flocculation mechanism. The cryotropic processing of the WPI-FG solutions led to the formation of diverse macroporous protein gel networks depending on the colloidal state of their biopolymeric precursors. Cryogel formation was primarily mediated via covalent (thiol-disulphide bond) bridging, whilst to a lesser extent, non-covalent interactions contributed to the overall stabilisation of the protein gel network. Although FG had a rather minor contribution to the formation of elastically active crosslinks (FG was partitioning mainly into the serum phase located in the macropores), its presence (at concentrations ≥0.75% wt.) improved the homogeneity and interconnectivity of the stranded protein network, whilst it reduced its colloidal instability and macroporosity.

An effective process for the separation of U(VI), Th(IV) from rare earth elements by using ionic liquid Cyphos IL 104

Separation and recovery of U(VI) and Th(IV) from rare earth minerals is a very challenging work in rare earth industrial production. In the present study, a homemade membrane emulsification circulation (MEC) extractor was used to separate U(VI) and Th(IV) from rare earth elements by using Cyphos IL 104 as an extractant. Batch experiments were carried out using a constant temperature oscillator to investigate the extraction parameters of the single element and the results indicated that Cyphos IL 104 could reach the extraction equilibrium within 30 min for all the three elements, i.e., U(VI), Th(IV), and Eu(III). Besides, the MEC extractor possessed a strong phase separation ability. The extraction efficiencies of U(VI), Th(IV), La(III), Eu(III) and Yb (III) increased with the increase of pH. La(III), Eu(III) and Yb(III) were hardly extracted when pH ≤ 1.50, which was beneficial for effectively separating U(VI) and Th(IV) from La(III), Eu(III) and Yb(III). In the multi-stages stripping experiments, when the stripping stage number was 3, the effective separation could be achieved by using HCl and H2SO4, since the stripping efficiency reached 80.0% and 100.0% for Th(IV) and U(VI), respectively. Slope method and FT-IR spectra showed that Cyphos IL 104 reacted with U(VI) and Th(IV) by chelation mechanism. The extraction of multi-elements indicated that U(VI) and Th(IV) could be well separated from the solution which contains all rare earth elements, and the extraction efficiencies of U(VI) and Th(IV) both were close to 100.0%. Based on the above experimental results, a flowchart for efficient separation of U(VI) and Th(IV) from rare earth elements was proposed.

Epithelial cells-enriched lncRNA SNHG8 regulates chromatin condensation by binding to Histone H1s.

Linker histone H1 proteins contain many variants in mammalian and can stabilize the condensed state of chromatin by binding to nucleosomes and promoting a more inaccessible structure of DNA. However, it is poorly understood how the binding of histone H1s to chromatin DNA is regulated. Screened as one of a collection of epithelial cells-enriched long non-coding RNAs (lncRNAs), here we found that small nucleolar RNA host gene 8 (SNHG8) is a chromatin-localized lncRNA and presents strong interaction and phase separation with histone H1 variants. Moreover, SNHG8 presents stronger ability to bind H1s than linker DNA, and outcompetes linker DNA for H1 binding. Consequently, loss of SNHG8 increases the amount of H1s that bind to chromatin, promotes chromatin condensation, and induces an epithelial differentiation-associated gene expression pattern. Collectively, our results propose that the highly abundant SNHG8 in epithelial cells keeps histone H1 variants out of nucleosome and its loss contributes to epithelial cell differentiation.

A strong phase separation polyurethane for self-repairing large-scale damage

We report a self-repairing polyurethane material with targeted repair effects on large-scale damage with a width of over 1 mm, which can be used to solve the problems of component failure caused by the damage of conventional coatings.

Morphology and Charge Transport Properties of P(NDI2OD-T2)/Polystyrene Blends

While the strategy of blending commodity insulating polymers with conjugated polymers has been previously applied to modify the properties of organic field-effect transistors (OFETs), comprehensive studies on the evolution of morphology and OFET performance with film composition are scarce. In this contribution, films comprising the n-type semiconducting polymer P(NDI2OD-T2) and the insulating polymer polystyrene (PS) are explored in detail. In particular, the electrical properties and film morphology of blends with a P(NDI2OD-T2) concentration ranging from 0.125 to 100 wt % are studied. Two regimes characterized by distinct dependencies of device mobility as a function of P(NDI2OD-T2) content are observed: Above 12.5 wt % P(NDI2OD-T2), the OFET mobility exhibits a weak dependence on P(NDI2OD-T2) concentration despite the presence of strong lateral phase separation, while below 12.5%, the device mobility is observed to decrease strongly with decreasing P(NDI2OD-T2) concentration attributed to disrupted surface connectivity of the P(NDI2OD-T2) phase. UV–vis absorption spectroscopy and grazing incidence wide-angle X-ray scattering (GIWAXS) measurements indicate that the aggregation and crystalline packing are not strongly affected by the presence of PS. Atomic force microscopy and scanning transmission X-ray spectro-microscopy reveal lateral phase separation for blends with compositions of 87.5 to 25 wt % P(NDI2OD-T2). Enrichment of P(NDI2OD-T2) at the film surface is confirmed by near-edge X-ray absorption fine structure spectroscopy, with a high P(NDI2OD-T2) surface composition (>80 wt %) maintained down to an overall blend composition of 12.5 wt % P(NDI2OD-T2). The strong decrease in OFET mobility for P(NDI2OD-T2) concentration less than 25 wt % is attributed to a loss of P(NDI2OD-T2) surface connectivity at low P(NDI2OD-T2) loading. We also observe a transition from face-on to edge-on dominated configuration at low P(NDI2OD-T2) content with GIWAXS, consistent with an edge-on surface layer that persists down to monolayer surface coverage.

Suppressing High-Current-Induced Phase Separation in Ni-Rich Layered Oxides by Electrochemically Manipulating Dynamic Lithium Distribution.

Understanding the cycling rate-dependent kinetics is crucial for managing the performance of batteries in high-power applications. Although high cycling rates may induce reaction heterogeneity and affect battery lifetime and capacity utilization, such phase transformation dynamics are poorly understood and uncontrollable. In this study, synchrotron-based operando X-ray diffraction is performed to monitor the high-current-induced phase transformation kinetics of LiNi0.6 Co0.2 Mn0.2 O2 . The sluggish Li diffusion at high Li content induces different phase transformations during charging and discharging, with strong phase separation and homogeneous phase transformation during charging and discharging, respectively. Moreover, by exploiting the dependence of Li diffusivity on the Li content and electrochemically tuning the initial Li content and distribution, phase separation pathway can be redirected to solid solution kinetics at a high charging rate of 7 C. Finite element analysis further elucidates the effect of the Li-content-dependent diffusion kinetics on the phase transformation pathway. The findings suggest a new direction for optimizing fast-cycling protocols based on the intrinsic properties of the materials.

Triphasic Polymer Particles Assembled via Microphase Separation with Multiple Functions.

This work investigated a unique type of triphasic colloidal particles composed of an azo polymer (PCNAZO), a fluorescent pyrene-containing polymer [P(MMA-co-PyMA)], and a poly(dimethylsiloxane)-based polymer (H2pdca-PDMS), focusing on the synthesis, forming mechanism, morphology control, and functions. The triphasic particles with well-defined morphologies were assembled through the microphase separation of the components in dichloromethane (DCM) droplets in an aqueous medium, induced by the gradual evaporation of the organic solvent. The real-time fluorescence emission spectra of the pyrenyl moieties and in situ microscopic observations show that the formation of the triphasic particles undergoes the segregation of the PCNAZO-rich phase, separation between P(MMA-co-PyMA)-rich and H2pdca-PDMS-rich phases, coalescence, and solidification in the dispersed droplets. The structure formation is due to the strong phase separation of the polymers as revealed by the calculations based on the Flory-Huggins theory. The morphologies and phase boundaries of the particles are found to be controlled by the interfacial energy between the phases and processing conditions. The triphasic particles thus obtained possess a series of interesting functions stemming from the polymers and the triple-compartmentalized structures. After being deposited on a substrate, the H2pdca-PDMS parts can tightly adhere on the surface, caused by the spreading nature of the polymer when slightly swelled by DCM. Upon irradiation with a linearly polarized laser beam at 488 nm, the azo polymer compartments show a significant elongation along the electric vibration direction of the polarized light, accompanied by the cooperative deformation of the H2pdca-PDMS pads. When dispersed in water and adhered on the substrate surface, the triphasic particles exhibit tunable colors originating from the fluorescence of the pyrenyl fluorophores and light absorption of the azo chromophores. The real-time investigation methods developed here could lead to the deep understanding of the structure formation process in the confined volume and be applied in phase-separation study of other polymers as well.

Efficient Solar Cells Based on a Polymer Donor with β-Branching in Trialkylsilyl Side Chains

Side-chain engineering is an important strategy in designing novel polymer semiconductor materials for high-efficient organic solar cells. The use of trialkylsilyl side chains can improve the photovoltaic efficiency by decreasing the energy of the HOMO of the polymer and improving its crystallinity and hole mobility. Compared to simple linear derivatives, α-branching in the alkyl groups of trialkylsilyl side chains causes strong aggregation and excessive phase separation in the photoactive layer, leading to poor device performance. β-Branching of the alkyl groups has not yet been used in trialkylsilyl side chains. Herein, we describe a new polymer (J77) with triisobutylsilyl side chains to investigate the effect of β-branching on the molecular aggregation, optical properties, energy levels, and photovoltaic properties. We find that compared to α-branching, β-branching of alkyl groups in trialkylsilyl side chains significantly reduces aggregation. This enables J77 to form blend morphologies in films that provide high-efficient solar cells in combination with different non-fullerene acceptors. Moreover β-branching of the alkyl groups in trialkylsilyl side chains lowers the HOMO energy level of J77 and increases the open-circuit voltage of J77-based solar cells without sacrificing short-circuit current density or fill factor.