Crystallization of polylactides examined by vibrational circular dichroism of intra- and inter-chain chiral interactions

Abstract

Herein, vibrational circular dichroism (VCD) measurements were carried out to study the kinetics of cold-crystallized poly(D-lactide) (PDLA) in molecular level via qualitative analysis. The amplification of VCD signals from intra-...

Polylactide cocrystals and gels

“…PLAs are found to exhibit polymorphism with five major crystalline forms ( α , β , γ , ε and stereocomplex (SC)) along with mesophases and disordered polymorphic forms ( α ′( δ ) and α″) based on the crystallization conditions. [ 2,5–32 ] Figure 1 shows the conditions for the formation and phase transition between different crystal polymorphs of PLLA.…”

“…Source: Reproduced with permission from Elsevier, 2020 [6] An intermediate state between crystalline and amorphous state was also reported for PLLA, which is termed as mesophase. [13,14,29,30,[66][67][68] The mesomorphic form can be induced by tensile drawing from the amorphous PLLA at a temperature that does not exceed 70 C, that is, $10 C above its glass transition temperature (T g ). [13,14] The addition of some components such as solvents and plasticizers to PLLA can also result in the formation of this intermediate structure.…”

“…PLLA shows polymorphism with different crystal modifications such as α , β , γ , α ′( δ ), α ″ and ε along with mesophase, depending upon the crystallization conditions. [ 2,5–32 ] These different polymorphs show different properties. Several factors, such as temperature, strain, additives, and solvent, can induce crystallization in PLLA.…”

“…Several factors, such as temperature, strain, additives, and solvent, can induce crystallization in PLLA. [ 2,5–31 ] Among these, the α form is considered as the most stable form of PLLA. PLLA can form cocrystals with several organic solvents or with CO 2 depending on their interactions with PLLA.…”

How Crystal Symmetry Dictates Non‐Local Vibrational Circular Dichroism in the Solid State

“…In recent years, vibrational circular dichroism (VCD) has come into focus, which is a ground-state property relying on a wealth of absorption bands (in the infrared region), many more than its electronic counterpart. [11] Being a very sensitive probe of molecular conformation and environment, VCD has been applied to a wide range of molecules including natural products, host-guest systems, peptides and proteins, nanoparticles or catalysts, [12][13][14][15][16][17][18][19][20][21] supramolecular organisation in the condensed phase, [8,[22][23][24][25][26][27][28][29][30][31][32] and the formation of chiral phases from achiral subunits. [5,33,34] In particular, the utility of solidstate VCD for the resolution of molecular chirality and supramolecular chirality has been noted by Sato and coworkers.…”