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1. Nanoconfined Crystallization in Poly(lactic acid) (PLA) and Poly(ethylene terephthalate) (PET) Induced by Various Forms of Premelt‐Deformation

   https://doi.org/10.1002/marc.202200293  

   Smith, Travis; Feng, Jiansheng; Zou, Lu; Gao, Min; Prévôt, Marianne; Wang, Shi‐Qing (July 2022, Macromolecular Rapid Communications)

   Abstract The processing–structure–property relationship using poly(lactic acid) (PLA) and poly(ethylene terephthalate) (PET) is explored. Specifically, both pre‐extension and preshear of amorphous PLA and PET above their glass transition temperaturesT_g, carried out in the affine deformation limit, can induce a specific type of cold crystallization during annealing, i.e., nanoconfined crystallization (NCC) where crystal sizes are limited to a nanoscopic scale in all dimensions so as to render the processed PLA and PET optically transparent. The new polymer structure after premelt deformation can show considerably enhanced mechanical properties. For example, premelt stretching produces geometric condensation of the chain network. This structural alternation can profoundly change the mechanical characteristics, e.g., turning brittle PLA ductile. In contrast, after preshear of amorphous PLA aboveT_g, the NCC containing PLA remains brittle, showing the importance to have geometric condensation from processing. Both AFM imaging and SAXS measurements are performed to verify that premelt deformation of PLA and PET indeed results in NCC from annealing that permits the strain‐induced cold crystallization to take place on the length scale of the mesh size of the deformed chain network. 

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2. Interfacial electrostatics of poly(vinylamine hydrochloride), poly(diallyldimethylammonium chloride), poly- l -lysine, and poly- l -arginine interacting with lipid bilayers

   https://doi.org/10.1039/C7CP07353D  

   McGeachy, A. C.; Dalchand, N.; Caudill, E. R.; Li, T.; Doğangün, M.; Olenick, L. L.; Chang, H.; Pedersen, J. A.; Geiger, F. M. (January 2018, Physical Chemistry Chemical Physics)

   Charge densities of cationic polymers adsorbed to lipid bilayers are estimated from second harmonic generation (SHG) spectroscopy and quartz crystal microbalance with dissipation monitoring (QCM-D) measurements. The systems surveyed included poly(vinylamine hydrochloride) (PVAm), poly(diallyldimethylammonium chloride) (PDADMAC), poly- l -lysine (PLL), and poly- l -arginine (PLR), as well as polyalcohol controls. Upon accounting for the number of positive charges associated with each polyelectrolyte, the binding constants and apparent free energies of adsorption as estimated from SHG data are comparable despite differences in molecular masses and molecular structure, with Δ G ads values of −61 ± 2, −58 ± 2, −57 ± 1, −52 ± 2, −52 ± 1 kJ mol −1 for PDADMAC 400 , PDADMAC 100 , PVAm, PLL, and PLR, respectively. Moreover, we find charge densities for polymer adlayers of approximately 0.3 C m −2 for poly(diallyldimethylammonium chloride) while those of poly(vinylamine) hydrochloride, poly- l -lysine, and poly- l -arginine are approximately 0.2 C m −2 . Time-dependent studies indicate that polycation adsorption to supported lipid bilayers is only partially reversible for most of the polymers explored. Poly(diallyldimethylammonium chloride) does not demonstrate reversible binding even over long timescales (>8 hours). 

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3. Ethyl cellulose- block -poly(benzyl glutamate) block copolymer compatibilizers for ethyl cellulose/poly(ethylene terephthalate) blends

   https://doi.org/10.1039/D4PY00688G  

   Chinn, Abigail F; Trindade_Coutinho, Isabela; Kethireddy, Saipranavi Reddy; Williams, Noah R; Knott, Kenneth M; Moore, Robert B; Matson, John B (August 2024, Polymer Chemistry)

   Luscombe, Christine; Anastasaki, Athina; Du_Prez, Filip; Frey, Holger; Hu, Rongrong; Klausen, Rebekka; Konkolewicz; Li, Zhibo; Li, Zi_Chen; Sardon, Haritz (Ed.)

   A block copolymer with the structure ethylcellulose-block-poly(benzy glutamate) was synthesizedviaring-opening polymerization and used as a compatibilizer to produce blends of ethylcellulose and poly(ethylene terephthalate). 

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4. Biaxial Stretching of PBAT/PLA Blends for Improved Mechanical Properties

   https://doi.org/10.3390/polym17192651  

   Rodriguez, Nikki; Gillor, Osnat; Guvendiren, Murat; Axe, Lisa (October 2025, Polymers)

   Biodegradable polymers offer a promising solution to the growing issue of global microplastic pollution. To effectively replace conventional plastics, it is essential to develop strategies for tuning the properties of biodegradable polymers without relying on additives. Biaxial stretching promotes anisotropic crystallization in polymer domains, thereby altering the mechanical performance of polymer blends. In this study, we employed a design of experiment (DoE) approach to investigate the effects of biaxial stretching at three drawing temperatures (Tds) and draw ratios (λs) on a biodegradable blend of poly(lactic acid) (PLA) and poly(butylene adipate-co-terephthalate) (PBAT), aiming to optimize both the strength and ductility. The DoE analysis revealed that the composition, the λ, the interaction between the λ and composition, and the interaction between the Td and composition significantly affect the elongation at break (εBreak). For the stress at break (σBreak), the most influential factors were the interaction between the λ and PLA concentration; a three-way interaction among the λ, PLA, and Td; the Td; the λ; and finally the PLA concentration alone. The optimal εBreak and σBreak were achieved at a λ = 5 × 5 and Td = 110 °C, with a composition of 10% PLA and 90% PBAT. The stretched samples exhibited higher crystallinity compared to the pressed samples across all compositions. This work demonstrates that in addition to the composition, the processing parameters, such as the λ and Td, critically influence the mechanical properties, enabling performance enhancements without the need for compatibilizers or toxic additives. 

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5. Dynamics of poly(methyl acrylate)/poly(methyl methacrylate)-grafted-Fe ₃ O ₄ nanocomposites

   https://doi.org/10.1039/D4SM00731j  

   Patil, Shalin; Mbonu, Christopher; Chou, Tsengming; Li, Ruhao; Wu, Di; Akcora, Pinar; Cheng, Shiwang (October 2024, Soft Matter)

   Nie, Zhihong (Ed.)

   Immiscible blends of poly(methyl acrylate) (PMA) and poly(methyl methacrylate) (PMMA) exhibit component dynamics and dynamics confinement effect at the PMA/PMMA-g-Fe₃O₄interface, suggesting new routes to control interface dynamics. 

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