“…[ 95 ] Different from these studies, Praveena et al investigated the structural changes of the blend gels in multiple length scales during heating. [ 60 ] For comparison, experiments were conducted with both homopolymer gels and blend gels. Variable temperature WAXD patterns obtained for the homo polymer and blend gel are given in Figure 12.…”
Section: Solvent‐induced Gel Formation In Pllamentioning
confidence: 99%
“…Temperature‐dependent WAXS patterns and normalized intensity of the selected reflections of (A and D) PLLA gel, (B and E) PDLA gel, and (C and F) PLLA/PDLA 50/50 blend gel during the heating process. Source : Reproduced with permission from Elsevier, 2022 [ 60 ] …”
Section: Solvent‐induced Gel Formation In Pllamentioning
confidence: 99%
“…Further heating resulted in the melting of gels. [ 60,80 ] In the blend gel, both homopolymers are crystallized to ε form and on further heating, it transformed into α form at 45°C. Here the transition takes place by excluding out the solvent molecules from the crystal lattice to the amorphous phase through locally disordered helical chains.…”
Section: Solvent‐induced Gel Formation In Pllamentioning
confidence: 99%
“…Schematic illustration of structural changes of PLLA/PDLA blend gels during the heating process. Source : Reproduced with permission from Elsevier, 2022 [ 60 ] …”
Section: Solvent‐induced Gel Formation In Pllamentioning
Synthetic biodegradable polyesters have emerged as an alternative to conventional petroleum-derived polymers for a diverse range of applications. Among these, polylactides are the most commercially successful biodegradable polymers. The presence of stereoregular chains makes poly(L-lactide) (PLLA) and poly(D-lactide) (PDLA) semicrystalline. The blending of enantiomeric PLLA and PDLA resulted in the stereocomplex formation due to non-covalent interactions of enantiomeric chains. PLLA exhibits different crystalline forms depending on the crystallization conditions with different chain conformations, as well as different chain packing structures. PLLA and its blend with PDLA are known to form cocrystals with certain solvents. This review focuses mainly on the recent progress in understanding the cocrystal formation, polymorphic phase transitions of these cocrystals, gelation mechanism and stereocomplex formation in blend gels of polylactides.
“…[ 95 ] Different from these studies, Praveena et al investigated the structural changes of the blend gels in multiple length scales during heating. [ 60 ] For comparison, experiments were conducted with both homopolymer gels and blend gels. Variable temperature WAXD patterns obtained for the homo polymer and blend gel are given in Figure 12.…”
Section: Solvent‐induced Gel Formation In Pllamentioning
confidence: 99%
“…Temperature‐dependent WAXS patterns and normalized intensity of the selected reflections of (A and D) PLLA gel, (B and E) PDLA gel, and (C and F) PLLA/PDLA 50/50 blend gel during the heating process. Source : Reproduced with permission from Elsevier, 2022 [ 60 ] …”
Section: Solvent‐induced Gel Formation In Pllamentioning
confidence: 99%
“…Further heating resulted in the melting of gels. [ 60,80 ] In the blend gel, both homopolymers are crystallized to ε form and on further heating, it transformed into α form at 45°C. Here the transition takes place by excluding out the solvent molecules from the crystal lattice to the amorphous phase through locally disordered helical chains.…”
Section: Solvent‐induced Gel Formation In Pllamentioning
confidence: 99%
“…Schematic illustration of structural changes of PLLA/PDLA blend gels during the heating process. Source : Reproduced with permission from Elsevier, 2022 [ 60 ] …”
Section: Solvent‐induced Gel Formation In Pllamentioning
Synthetic biodegradable polyesters have emerged as an alternative to conventional petroleum-derived polymers for a diverse range of applications. Among these, polylactides are the most commercially successful biodegradable polymers. The presence of stereoregular chains makes poly(L-lactide) (PLLA) and poly(D-lactide) (PDLA) semicrystalline. The blending of enantiomeric PLLA and PDLA resulted in the stereocomplex formation due to non-covalent interactions of enantiomeric chains. PLLA exhibits different crystalline forms depending on the crystallization conditions with different chain conformations, as well as different chain packing structures. PLLA and its blend with PDLA are known to form cocrystals with certain solvents. This review focuses mainly on the recent progress in understanding the cocrystal formation, polymorphic phase transitions of these cocrystals, gelation mechanism and stereocomplex formation in blend gels of polylactides.
“…The two enantiomers of PLA, PLLA and PDLA, are mixed in a 1:1 ratio, which can be stereocomplexed to form the physical force of hydrogen bonds, and can improve their thermal stability. The introduction of polylactic acid can provide the gel with hydrogen bonding [ 28 , 29 ]. L-histidine is an essential human amino acid, which is non-toxic, antibacterial and biocompatible.…”
Hydrogel is a good drug carrier, widely used in the sustained-release aspect of tumor drugs, which can achieve the continuous release of drugs to the tumor sites. In this study, diethylene glycol monomethyl ether methacrylate (MEO2MA) and poly (ethylene glycol) methyl ether methacrylate (OEGMA) are temperature-sensitive monomers. N-Methacryloyl-L-Histidine (Mist) is pH sensitive monomer and ligand for metal coordination bond. The temperature-sensitive monomers and pH sensitive monomer with stereocomplex of modified polylactic acid (HEMA-PLLA30/PDLA30) were mixed, under 2,2’-azobis (2-methylpropionitrile) (AIBN) as radical initiator, polymer was formed by free-radical polymerization. The polymer was then immersed in ZnSO4 solution, the imidazole group of Mist monomer forms a tridentate metal coordination bond with Zn2+, temperature/pH double-responsive and physical double-crosslinked hydrogel was finally obtained. Comparing the hydrogen bond hydrogel, hydrogen bond and metal coordination bond double crosslinking hydrogel, metal coordination bond hydrogel, testing thermal stability, viscoelasticity, swelling, and morphology of three hydrogels. In addition, using UV-Visible spectroscopy (UV-Vis) to test the sustained release of the hydrophobic drug doxorubicin hydrochloride (DOX-HCl) in the human tumor environment (37 °C, pH = 5). We found that the temperature/pH double-responsive and physical double-crosslinked hydrogel had the most potential for the sustained drug release.
Achieving predictable and programmable two‐dimensional (2D) structures with specific functions from exclusively organic soft materials remains a scientific challenge. This article unravels stereocomplex crystallization‐driven self‐assembly as a facile method for producing thermally robust discrete 2D‐platelets of diamond shape from degradable semicrystalline polylactide (PLA) scaffolds. The method involves co‐assembling two PLA stereoisomers, namely, PY‐PDLA and NMI‐PLLA, which form stereocomplex (SC)‐crystals in isopropanol. By conjugating a well‐known Förster resonance energy transfer (FRET) donor and acceptor dye, namely, pyrene (PY) and naphthalene monoimide (NMI), respectively, to the chain termini of these two interacting stereoisomers, a thermally robust FRET process can be stimulated from the 2D array of the co‐assembled dyes on the thermally resilient SC‐PLA crystal surfaces. Uniquely, by decorating the surface of the SC‐PLA crystals with an externally immobilized guest dye, Rhodamine‐B, similar diamond‐shaped structures could be produced that exhibit pure white‐light emission through a surface‐induced two‐step cascade energy transfer process. The FRET response in these systems displays remarkable dependence on the intrinsic crystalline packing, which could be modulated by the chirality of the co‐assembling PLA chains. This is supported by comparing the properties of similar 2D platelets generated from two homochiral PLLAs (PY‐PLLA and NMI‐PLLA) labeled with the same FRET pair.
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