In:
Polymer Chemistry, Royal Society of Chemistry (RSC), Vol. 13, No. 45 ( 2022), p. 6302-6311
Abstract:
In this work, a series of hydroxy-terminated oxalamide segments containing different aliphatic spacer lengths (OXA- n , HO-(CH 2 ) n -NHCOCONH-(CH 2 ) n -OH, n = 2, 4 and 6) were designed as initiators for l -lactide ring-opening polymerization and then poly( l -lactide) with oxamide segments in the middle (PLLA OXA- n ) were synthesized. The effects of OXA- n on the formation of hydrogen bonds were explored. The OXA- n induced H-bonds not only enhanced the crystallization temperature ( T c , from 99.5 °C to 105.2 °C) and the crystallinity ( X c , from 10.3% to 38.2%) of PLLA but also retained a high transmittance value (81–82% at 600 nm). The influence of H-bonding on polymer nucleation and crystallization was investigated by a combination of experiments and molecular dynamics (MD) simulations. The length of the aliphatic spacer (OXA-6 compared with OXA-2 and OXA-4) increased the flexibility of PLLA, thereby increasing the probability of H-bond formation via oxalamide segments. The increased probability of H-bond formation could subsequently change the molecular topology or steric hindrance which leads to a decrease in entropy and a difference in molecular chain conformation, which further promotes the locally ordered structure of PLLA during crystallization. Therefore, this work provides a novel route to synthesize PLLA with inherently fast(er) crystallization rates by introducing oxalamide H-bonding segments.
Type of Medium:
Online Resource
ISSN:
1759-9954
,
1759-9962
Language:
English
Publisher:
Royal Society of Chemistry (RSC)
Publication Date:
2022
detail.hit.zdb_id:
2528812-X
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