Artykuły CBMiM PAN

Displaying 1 - 4 of 4 records

An efficient alternative to DBU in the oxathiaphospholane (OTP) method for the solid phase synthesis of P-stereodefined phosphorothioate analogs
(The Royal Society of Chemistry, 2024-07-04) Jastrzębska, Katarzyna; Centrum Badań Molekularnych i Makromolekularnych Polskiej Akademii Nauk
This study presents a modified (extended) 1,3,2-oxathiaphospholane (OTP) method for the synthesis of P-stereodefined phosphorothioate analogs in the presence of previously unused organic bases. TBD (5,7-triazabicyclo[4.4.0]dec-5-ene) and Verkade's proazaphosphatrane (2,8,9-trimethyl-2,5,8,9-tetraaza-1-phosphabicyclo[3.3.3]undecane) are herein used for the first time as efficient organic bases compared to DBU, which is commonly used in the OTP approach. OTP method for the synthesis of P-stereodefined phosphorothioate has been extended to use activators TBD and Verkade base, which can be used interchangeably with DBU.
P-Stereodefined morpholino dinucleoside 3′,5′-phosphorothioates†
(The Royal Society of Chemistry, 2024-10-11) Jastrzębska, Katarzyna; Antończyk, Patrycja; Dolot, Rafał; Centrum Badań Molekularnych i Makromolekularnych Polskiej Akademii Nauk
Here, we present for the first time the synthesis of P-stereodefined morpholino phosphorothioate analogs by using a modified 1,3,2-oxathiaphospholane method (OTP method) and provide valuable structural insights into their stereochemistry. N-(2-Thio-4,4-pentamethylene-1,3,2-oxathiaphospholane) derivatives of morpholino-type nucleosides (mU-OTPs) were synthesized, separated into pure P-diastereomers and used to prepare P-stereodefined morpholino dinucleoside 3 ',5 '-phosphorothioates. We present P-stereodefined morpholino phosphorothioate analogs and provide valuable structural insights into their stereochemistry. These P-diastereomerically pure analogs could have a significant impact in the field of nucleic acid therapeutics.
Role of Minor Phase Morphology on Mechanical and Shape-Memory Properties of Polylactide/Bio-Polyamide Nanocomposite
(MDPI, 2024-08-26) Bondarenko, Vladislav; Hosseinnezhad, Ramin; Voznyak, Andrei; Physics and Mathematics Department, Kryvyi Rih State Pedagogical University, Kryvyi Rih, Ukraine; Centrum Badań Molekularnych i Makromolekularnych Polskiej Akademii Nauk; Department of Technological and Professional Education, Kryvyi Rih State Pedagogical University, Kryvyi Rih, Ukraine
In situ-generated nanofibrillar polymer–polymer composites are excellent candidates for the production of polymer materials, with high mechanical and SME properties. Their special feature is the high degree of dispersion of the in situ-generated nanofibers and the ability to form entangled nanofiber structures with high aspect ratios through an end-to-end coalescence process, which makes it possible to effectively reinforce the polymer matrix and, in many cases, increase its ductility. The substantial interfacial area, created by the in situ formed fiber/matrix morphology, significantly strengthens the interfacial interactions, which are crucial for shape fixation and shape recovery. Using the polylactide/bio-polyamide (PLA/PA) system as an example, it is shown that in situ PA fibrillation improves the mechanical and shape-memory properties of PLA. The modulus of elasticity increases by a factor of 1.4, the elongation at break increases by a factor of 30, and the shape-strain/fixity ratio and shape recovery increase from 80.2 to 97.4% and from 15.5 to 94.0%, respectively. The morphology of the minor PA phase is crucial. The best result is achieved when a physically entangled nanofibrous network is formed.
Approaches to Control Crazing Deformation of PHA-Based Biopolymeric Blends
(MDPI, 2023-10-26) Hosseinnezhad, Ramin; Elumala, Dhanumalayan; Vozniak, Iurii; Centrum Badań Molekularnych i Makromolekularnych Polskiej Akademii Nauk
The mechanical behavior of polymer materials is heavily influenced by a phenomenon known as crazing. Crazing is a precursor to damage and leads to the formation of cracks as it grows in both thickness and tip size. The current research employs an in situ SEM method to investigate the initiation and progression of crazing in all-biopolymeric blends based on Polyhydroxyalkanoates (PHAs). To this end, two chemically different grades of PHA, namely poly(hydroxybutyrate) (PHB) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBHV), were melt-blended with polybutyrate adipate terephthalate (PBAT). The obtained morphologies of blends, the droplet/fibrillar matrix, were highly influenced by the plasticity of the matrices as well as the content of the minor phase. Increasing the concentration of PBAT from 15 to 30 wt.% resulted in the brittle to ductile transition. It changed the mechanism of plastic deformation from single craze-cracking to homogeneous and heterogeneous intensified crazing for PHB and PHBHV matrices, respectively. Homogeneous tensile crazes formed perpendicularly to the draw direction at the initial stages of deformation, transformed into shear crazes characterized by oblique edge propagation for the PHBHV/PBAT blend. Such angled crazes suggested that the displacement might be caused by shear localized deformation. The crazes’ strength and the time to failure increased with the minor phase fibers. These fibers, aligned with the tensile direction and spanning the width of the crazes, were in the order of a few micrometers in diameter depending on the concentration. The network of fibrillar PBAT provided additional integrity for larger plastic deformation values. This study elucidates the mechanism of crazing in PHA blends and provides strategies for controlling it.

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