查看更多>>摘要：Generic polymer models capturing the chain connectivity and excluded-volume interactions between polymer segments can be clas-sified,according to whether or not the 3D integral of the latter diverges,into hard-and soft-core models.Taking homogeneous systems of com-pressible homopolymer melts(or equivalently homopolymer solutions in an implicit,good solvent)in the continuum as an example,we recently compared the correlation effects on the structural and thermodynamic properties of the hard-and soft-core models given by the polymer refer-ence interaction site model(PRISM)theory with the Percus-Yevick(PY)closure(Polymers 2023,15,1180).Here we analyzed in detail the numeri-cal errors and behavior of the interchain pair correlation functions(PCFs)given by the PRISM-PY calculations of these models using an efficient numerical approach that we proposed.Our numerical approach has the least number of independent variables to be iteratively solved,analytical-ly treats the discontinuities caused by the non-bonded pair potential(such as that of the hard spheres)and takes only the inverse Fourier trans-form of the interchain indirect PCF between polymer segments(which is continuous and decays towards 0 with increasing wavenumber much faster than both the interchain direct and total PCFs),and is essential for us to accurately solve the PRISM-PY theory for chain length N as large as 106.To capture the correlation-hole effect,the real-space cut-off in the PRISM calculations should be proportional to the square root of N.
查看更多>>摘要：In the domain of high-performance engineering polymers,the enhancement of mechanical flexibility in poly(phenylene sulfide)(PPS)resins has long posed a significant challenge.A novel molecular structure,designated as PP-He-IS,wherein imide rings and an aliphatic hexylene chain are covalently incorporated into the PPS backbone to enhance its flexibility,is introduced in this study.Molecular dynamics(MD)simula-tions are employed to systematically explore the effects of diversifying the backbone chain structures by substituting phenyl units with alkyl chains of varying lengths,referred to as PP-A-IS where"A"signifies the distinct intermediary alkyl chain configurations.Computational analyses reveal a discernable decrement in the glass transition temperature(Tg)and elastic modulus,counterbalanced by an increment in yield strength as the alkyl chain length is extended.Notably,the PP-He-IS variant is shown to exhibit superior yield strength while simultaneously maintaining re-duced elastic modulus and Tg values,positioning it as an advantageous candidate for flexible PPS applications.Mesoscopic analyses further indi-cate that structures such as PP-He-IS,PP-Pe-IS,and PP-Bu-IS manifest remarkable flexibility,attributable to the presence of freely rotatable carbon-carbon single bonds.Experimental validation confirms that a melting temperature of 504 K which is lower than that of conventional PPS,and lower crystallinity are exhibited by PP-He-IS,thereby affording enhanced processability without compromising inherent thermal stability.Novel insights into the strategic modification of PPS for mechanical flexibility are thus furnished by this study,which also accentuates the pivotal role played by molecular dynamics simulations in spearheading high-throughput investigations in polymer material modifications.
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