Macromolecular Chemistry and Physics最新文献

Polypropylene (PP) has attracted significant attention as a recyclable thermoplastic for high-voltage direct current (HVDC) cable insulation, potentially replacing conventional cross-linked polyethylene (XLPE). This study systematically investigates the effects of cooling rate (10, 20, and 30°C/min) during melt processing on the crystalline structure and electrical properties of PP insulation material. Through comprehensive characterization using polarized optical microscopy, X-ray diffraction, and differential scanning calorimetry, the results indicate that increased cooling rates effectively suppress spherulite formation, reducing average spherulite diameter and decreasing crystallinity from 52% to 44%. These structural modifications yield a 450% enhancement in volume resistivity from 4.11 × 10¹³ to 2.26 × 10¹⁴ Ω m, along with a 21.4% improvement in DC breakdown strength from 224 to 272 kV/mm when measured at 70°C. However, space charge measurements reveal the presence of space charge accumulation at elevated temperatures, which we attribute to lattice defects induced by rapid crystallization. The results establish a quantitative processing-structure-property relationship, showing that controlled cooling rate optimization can significantly enhance PP's electrical performance for HVDC applications while maintaining its recyclability advantage over XLPE.

The aim of this study was to incorporate attapulgite (ATP) (a naturally abundant nanoclay found in Algeria) into biodegradable poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) in order to enhance the thermal, crystallization, and viscoelastic properties of the resulting bionanocomposites. PHBV/ATP bionanocomposites containing 3 and 5 wt.% ATP was fabricated via melt compounding. Comprehensive physicochemical characterization of purified ATP confirmed its nano-fibrous morphology and excellent thermal stability, as evidenced by SEM and TGA analyses. At 3 wt.% loading, ATP was homogeneously dispersed within the PHBV matrix, leading to significant improvements in thermal stability (increased onset decomposition temperature), enhanced crystallization behavior (higher crystallinity degree), and improved complex viscosity and storage modulus, indicating a reinforcement effect on the polymer's viscoelastic response. These enhancements are attributed to effective polymer-clay interfacial interactions and the high aspect ratio of ATP nanorods. However, at 5 wt.% ATP, SEM revealed partial aggregation of the nanoclay, which disrupted the polymer matrix continuity and resulted in marginally reduced performance compared to the 3 wt.% formulation. This work highlights the potential of valorizing locally sourced Algerian ATP as a sustainable nanofiller for producing high-performance, eco-friendly PHBV-based bionanocomposites for applications such as packaging and agricultural materials.

Photoresists (PRs) are light-sensitive polymers used in photolithography to fabricate micropatterns on substrates. This study proposes a microphase separation strategy to overcome the flexibility limitations associated with typical acrylic-based PRs in patterning applications by incorporating poly(ε-caprolactone)-b-poly(n-butyl acrylate) (PCL-b-PnBA) block copolymer (BCP) additives. A BCP additive was prepared using a dual-functional initiator, ethyl 2-hydroxyethyl-2-bromoisobutyrate (HEBiB), which can efficiently combine two eco-friendly polymerization techniques of ring-opening polymerization (ROP) and supplemental activator and reducing agent atom transfer radical polymerization (SARA ATRP) (i.e., ROP-Є-SARA ATRP), allowing for precise control over compositions and compatibility. For synthesizing the PRs, methyl methacrylate (MMA), acrylic acid (AA), and maleic anhydride (MAn) monomers were utilized to afford two randomly copolymerized pre-polymers, namely, P(MMA-r-AA) and P(MMA-r-MAn). Following esterification with allyl bromide and hydroxyethyl methacrylate (HEMA), two PR systems (abbreviated as PMAV and PMMAnMA, respectively) were prepared. By mixing various amounts of the PCL₁₁₉-b-PnBA₉₆ (M_n,NMR = 26,080; Φ_PCL = 0.49; Đ = 1.28) and two PRs following UV-curing reactions, high transmission films can be obtained. Their photopatterning and mechanical properties were improved, owing to the occurrence of microphase separation within the matrix. Microstructure-containing matrices were characterized by small-angle X-ray scattering (SAXS). The compatibility of the BCP additive with commercially available polyimide acrylate (PIA) and polyurethane acrylate (PUA) PRs was examined. Lithographic evaluations showed improved resolution, uniformity, and developer resistance, highlighting the potential of PCL-b-PnBA-modified resins for high-performance photoresists in flexible electronic fabrications and next-generation lithography.

Stretchable electronic devices have increasingly received interest both in the academic and industrial communities because of their potential to break the limitations of traditional rigid devices and further expand the fields of applications, especially in wearable and implantable devices. As the key component of stretchable transistors in stretchable electronics, the design of a suitable stretchable semiconductor is extremely urgent and essential, while the natural flexibility of polymer semiconductor makes it a promising material for stretchable electronics. However, high mechanical stretchability and high mobility simultaneously in one polymer semiconductor is still a challenge, because the two properties are opposite in relationship. In this review, recent strategies to enhance mechanical stretchability in polymer semiconductors while maintaining the mobilities are discussed, including molecular design, physical blending, and near-amorphous polymer, with emphasis on the control of both thin-film morphology and polymer-chain dynamics in the stretchable polymer semiconductor film. Last, challenges and outline future research perspectives of stretchable polymer semiconductors are discussed in conclusions and future prospects.

Photocurable resins have been widely utilized in industrial areas such as coatings, inks and 3D printing as the photocuring technology has the merits of fast curing rate at ambient temperature, low energy consumption, low volatile organic chemical (VOC) emissions, etc. However, affected by the crises including depletion of petroleum resources, greenhouse effect and environmental pollution, developing such polymer materials from renewable biomass have attracted extensive attention. In this paper, the researches on the preparation, high performance, and functionalization of photocurable resin derived from biomass like plant oil, natural phenol, cellulose, and lignin in recent years are reviewed. The structure–property relationships and industrial application potential of the photocurable resins are systematically explored, and the development direction of this field is prospected, which provide theoretical guidance and technical support for the subsequent development of high-performance and functional biomass-derived photocurable resins.

Pn-M_n,am-φ_LC block copolymers, composed of a side-on side-chain liquid crystal (LC) block and an amorphous poly(butyl methacrylate) (PBMA) block, were investigated to elucidate their microphase-separated morphology and LC orientation at the phase boundary. The LC block, at volume fractions φ_LC = 24%–70%, contains mesogens laterally attached via spacers of length n = 6–12. When φ_LC exceeds 50%, lamellar microdomains form and gradually transform into PBMA-cylinder microdomains. LC director orientation depends on n: perpendicular alignment occurs at n = 6 and 8, while parallel alignment appears at n = 10 and 12. At φ_LC below 40%, core–shell microdomains emerge, featuring a PBMA core and LC shell within a PBMA matrix. This morphology results from volume and backbone length imbalance, and chain conformation asymmetry. Although the LC block has a shorter contour length than PBMA, it occupies a larger volume due to its high molecular weight. The LC block stretches along the normal to the microdomain boundary, while the PBMA block adopts a slightly elongated random-coil conformation. These findings demonstrate that side-on side-chain LC blocks enable systematic control over microdomain morphology and LC orientation by tuning molecular parameters, offering insights for designing nanostructured materials.

Given the defects existing in traditional additive flame retardants, it is of great research significance to endow polyurethane (PU) with intrinsic flame retardancy through molecular structure design. The polyester polyol (PAHI) is first synthesized by esterification with 1, 6-adipic acid, 1, 6-hexanediol, and itaconic acid, and then the itaconic acid reacts with 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) to form a polyester polyol (PAHI-DOPO). The PAHI-DOPO monomer is used as part of PU flexible section to be cured with diphenylmethane diisocyanate (MDI) to obtain PU with an increased LOI value of 30.4% and flame-retardant grades reaching the V-0 level. Moreover, a small amount of PAHI-DOPO can significantly enhance the mechanical properties of PU, resulting in a strength increase from 15.1 to 18.2 MPa and an improvement in toughness from 753% to 815%. Compared with direct addition of equal amount of DOPO as flame retardant, the transparency and mechanical properties of PU are significantly improved. Interestingly, the intrinsic flame-retardant approach effectively avoids the sharp decrease in mechanical properties that occurs when the flame retardant migrates from the samples upon immersion in water. Thus, this synthetic flame-retardant polyester polyol offers an efficient, durable, and environmentally friendly approach to enhancing the flame-retardancy of PU.