Chi-An Dai

A hierarchical–interfacial design enables ultralow-viscosity, low-CTE epoxy composites at extreme filler loadings, unlocking flowable, low-warpage encapsulation for advanced electronic packaging.

Developing sustainable, high-performance elastomers for tire applications has become a growing priority for the chemical industry, driven by environmental mandates and the functional demands of modern transportation. In response, additive engineering is increasingly employed to replace conventional silane coupling agents (SCAs), which raise environmental concerns and constrain optimization of the rolling resistance (RR)–wet grip (WG) trade-off. A central challenge in this domain lies in elucidating how interfacial modifiers reconfigure filler architecture and influence macroscopic properties. In this study, we introduce a novel small angle X-ray scattering (SAXS)-guided analytical framework that integrates a mass-fractal model with a gel-like network model to resolve the hierarchical three-tiered structure of poly(ethylene glycol) (PEG)-modified, silica-filled tire compounds. This hybrid model enables the quantitative extraction of cluster radius and—critically—the contribution of occluded rubber domains, a morphological feature often suggested visually but seldom structurally characterized. In contrast to a widely used SCA, which enhances filler dispersion via covalent silica–rubber linkages, PEG induces greater filler aggregation and occluded rubber formation through hydrogen bonding, while simultaneously promoting interfacial slippage under dynamic strain. These coexisting mesoscale features—quantified via SAXS and directly linked to dynamic mechanical properties—result in a 40% reduction in RR, a 14% enhancement in WG, and 81% higher stiffness relative to the SCA-modified system. This mechanistic breakthrough diverges from conventional dispersion-centric frameworks and establishes PEG as a viable SCA-free alternative. More broadly, this work demonstrates a transferable, structure-informed strategy for the design of next-generation high-performance, environmentally friendly rubber nanocomposites.

The increasing prevalence of cataracts underscores the urgent need for intraocular lens (IOL) materials that provide optical clarity, foldability, glistening resistance, and long-term biocompatibility. In this study, we developed hydro-amphiphilic ternary copolymers composed of styrene, hydroxyethyl methacrylate (HEMA), and poly(ethylene glycol) phenyl ether acrylate (PEGPEA) to address these requirements. This rational design integrates the strength and refractive index of hydrophobic styrene with the flexibility and hydrophilicity of HEMA and PEGPEA. The optimized formulation (H3), comprising 50 wt % HEMA, 30 wt % PEGPEA, and 20 wt % styrene, showed excellent transparency after accelerated aging, sufficient modulus and elongation for safe surgical handling, and low cytotoxicity in CCK-8 assays. Cytokine analyses revealed no significant inflammatory response compared to a commercial hydrophobic acrylic IOL. These findings highlight hydro-amphiphilic copolymers as a promising next-generation material platform for IOLs, offering a biocompatible, glistening-free, and foldable solution for enhanced surgical outcomes and long-term patient satisfaction.

Composite electrospun membranes composed of quaternized chitosan, chitosan, poly(ethylene oxide) and either caffeic acid or berberine demonstrated improved hydrophilicity and enhanced antibacterial activity against E. coli and S. aureus.

The recent past has witnessed remarkable progress in organic electronics, driven by the quest for flexible, lightweight, and cost-effective electronic devices. Semiconducting polymers (SCPs) have emerged as key materials in this field, offering unique electronic and optoelectronic properties along with mechanical flexibility. This study focuses on designing, synthesizing, and utilizing novel donor-acceptor (D-A) copolymer-based SCPs introducing a difluorothiophene moiety in the polymeric backbone. The importance of fluorine substitution for backbone planarity was verified by density functional theory calculations, comparing it with a nonfluorine substituted counterpart. Through the Unidirectional Floating Film Transfer Method (UFTM), we fabricated highly oriented thin films, resulting in increased optical anisotropy with dichroic ratios reaching 19.3 in PC20-FT thin films, one of the highest optical anisotropy observed for solution processable SCP thin films. X-ray diffraction and atomic force microscopy results validated the increase in the crystallinity and domain size with the increasing alkyl chain length. Finally, we elucidate these findings in the context of electrical applications by fabricating organic field-effect transistors revealing anisotropic charge transport achieving a promising mobility of 1.24 cm(2)V(-1)s(-1) and mobility anisotropy of 39.5. This study offers insights into the design principles and performance optimization of SCP-based devices, paving the way for advancements in plastic electronics.

The physical and mechanical properties of novel bio-based polymer blends of polylactic acid (PLA), poly(butylene succinate) (PBS), and poly (butylene adipate-co-terephthalate) (PBAT) with various added amounts of nanohydroxyapatite (nHA) were investigated in this study. The formulations of PLA/PBS/PBAT/nHA blends were divided into two series, A and B, containing 70 or 80 wt% PLA, respectively. Samples of four specimens per series were prepared using a twin-screw extruder, and different amounts of nHA were added to meet the regeneration needs of bone graft materials. FTIR and XRD analyses were employed to identify the presence of each polymer and nHA in the various blends. The crystallization behavior of these blends was examined using DSC. Tensile and impact strength tests were performed on all samples to screen feasible formulations of polymer blends for bone graft material applications. Surface morphology analyses were conducted using SEM, and the dispersion of nHA particles in the blends was further tested using TEM. The added nHA also served as a nucleating agent aimed at improving the crystallinity and mechanical properties of the blends. Through the above analyses, the physical and mechanical properties of the polymer blends are reported and the most promising bone graft material formulations are suggested. All blends were tested for thermal degradation analysis using TGA and thermal stability was confirmed. The water absorption experiments carried out in this study showed that the addition of nHA could improve the hydrophilicity of the blends.

Well‐defined block copolymers consisting of hyperbranched polyamide (HBPA) and polystyrene (PSt) are synthesized, and their self‐assembled structures in solutions are investigated. Atom transfer radical polymerization (ATRP) of styrene initiated from an HBPA macroinitiator, prepared by the chain‐growth condensation polymerization of an AB₂ monomer, followed by introduction of an ATRP initiator unit at the focal point, gives the desired block copolymers, PSt‐b‐HBPAs, with well‐defined molecular weight and narrow molecular weight distribution. The block copolymer (PSt/HBPA = 84/16) undergoes self‐assembly in toluene to form spherical micelles (≈10–20 nm), but upon addition of methanol to the toluene solution (toluene/methanol = 0.97/0.03), the morphology changes to vesicles. Further addition of methanol (toluene/methanol = 0.90/0.10) leads to an increase in vesicle size (200–300 nm) and the morphology further transforms from vesicles to large aggregates (>100 nm) at toluene/methanol = 0.80/0.20. In the case of PSt‐b‐HBPA with shorter PSt segments (PSt/HBPA = 76/24 and 60/40), spherical micelles are formed in toluene, but the micelle morphology remains unchanged when 10 wt% methanol is added, though large aggregates (>100 nm) are still formed in toluene/methanol = 0.80/0.20. Interestingly, the morphological transformations of linear/hyperbranched block copolymers are different from those of their double linear block copolymer counterparts.

Quantum efficiencies remain a critical issue for general applications of semiconducting polymers in optoelectronics and others. In this work, we demonstrate that nearly 100% quantum efficiencies (eta's) in thin solid films can be reached when the polymer molecules are mechanically stretched into molecular confinement. We selected three conjugated polymers of varied backbone stiffness and interchain coupling, prepared in both diluted and pristine states. All of the polymers when highly diluted (c = 0.1 wt %) exhibited massive increases after stretching to very large strains (similar to 300-500%) via micronecking, with the rigid polyfluorene (PFO) and semirigid MEH-PPV both manifesting eta approximate to 90%, while the most flexible yet regioregular polythiophene (P3HT-rr) exhibited a 10-fold increase to similar to 21%. In the pristine state, molecular aggregation and interchain coupling curtail development of the molecular confinement, but the large-strain deformation still enhances eta's significantly, to similar to 90% (PFO) and similar to 55% (MEH-PPV) despite no increases for the crystalline P3HT-rr. Moreover, upon substitution by a bulkier side-group to reduce interchain coupling, the pristine films of polythiophene (P3EHT) exhibited a similar to 3-fold increase of eta after the stretching. The nearly 100% of eta's in fully stretched molecules indicates that the in situ self-trapping occurring via sub-picosecond backbone interactions can be mostly responsible for energy dissipations and quite suppressible by segmental stress control. The mechanical confinement effects also indicate the fundamental role of molecular mechanics during stabilization and migration of photoexcited charges.