Composite banded core and non-banded shell transition patterns in stereocomplexed poly(lactide acid) induced by strongly interacting poly(p-vinyl phenol)

Abstract

Banded cores and non-banded shells with transitional patterns in stereocomplexed poly(lactic acid) sc-PLA (PLLA : PDLA ¼ 1 : 1) interacting with amorphous poly(p-vinyl phenol) (PVPh) (20-30 wt%) were investigated by using polarized optical (POM), atomic force (AFM), and scanning electron microscopy (SEM). The central core of the spherulites is ring-banded, which transitions into non-banded patterns on the outer peripheral in sc-PLA/PVPh blends crystallized at T c ¼ 160-180 C. This composite crystal morphology is distinctly different from that of the neat sc-PLA, which is a Maltese-cross without any ring patterns in spherulites. The bands in the core region are also dramatically different from those bands with birefringence contrasts observed in classical ring-bands. The bands in the core show only crystal topology and no birefringence difference. Both regions of ring-banded and non-banded crystals are composed of edge-on lamellae, but the central-core lamellae undergo periodical waving up and down. The specific stage-wise and preferential interactions between PVPh and sc-PLA and glass substrate, which simultaneously occur during amorphous PVPh rejection and growth processes, were evaluated as some plausible kinetic reasons for the special composite crystal morphology of sc-PLA complex induced by blending with PVPh. † Electronic supplementary information (ESI) available: The crystalline morphology of sc-PLA/PVPh (95/5), (90/10), and (80/20) blends at various T c s. AFM micrograph of inter-lamellar junction in non-banded region. The FTIR spectra of sc-PLA/PVPh at various blend compositions. The crystalline morphology of sc-PLA/PVPh (70/30) blend at T c ¼ 170 C and various t max . See

Crystallization of triethyl‐citrate‐plasticized poly(lactic acid) induced by chitin nanocrystals

“…Further examination revealed the different types of spherulites shown in Figure 8(c-e). Ni'mah et al 32 reported a similar type of lamellar pattern for the spherulites of PLA. Specifically, the circular fibrous texture of the lamellae leads to the formation of a circular ring within the periphery of the spherulites.…”

“…A completely different type of lamellar pattern of the spherulite, a scattered lamellar pattern, is observed in Figure 8(e). Ni'mah et al 32 reported a similar type of lamellar pattern for the spherulites of PLA. Both the POM and the SEM observations revealed that these different types of spherulites have different lamellar arrangements.…”

Unusual Radiating-Stripe Morphology in Nonequimolar Mixtures of Poly(l-lactic acid) with Poly(d-lactic acid)

“…1 The fact that the morphology of a highly diluted scPLA [such as poly(p-vinyl phenol) or other interacting amorphous polymers] has a highly dendritic structure of dual patterns composed of a ring-banded dendritic pattern in the core center and a nonbanded dendritic pattern in the outer rim region enclosing the banded core has been proven earlier. 41 The highly asymmetric nonracemic PLLA/PDLA = 98/2, 94/6, and 90/10 can in reality be regarded as a "highly diluted" scPLA dispersing in a large quantity of excess PLLA chains. Thus, naturally, the excess PLLA, upon holding at T c = 140 °C for long enough time, grows from these fibrous crystal tips and starts to aggregate along the straight dendrites, finally packing into a sword-blade shape with a diamond-lozenge tip, as shown in Figure 9B.…”

Preparation and Characterization of Poly(L-lactic acid) Films Plasticized with Glycerol and Maleic Anhydride

“…Some studies have reported blends of PLLA and other materials, such as blends of PLLA with other crystalline polymers, i.e. PLLA with poly(ethylene oxide (PEO) (Lee et al, 2012); PLLA with poly(D-lactic acid) (PDLA) (Ni'mah et al, 2014); PLLA with other amorphous polymers, i.e. PLLA with atactic poly(methyl methacrylate) (aPMMA) (Woo et al, 2014); PLLA with poly(vinyl phenol) (PVPh) (Ni'mah et al, 2014); PLLA with elastomeric polymers such as natural rubber (Desa et al, 2016;Nofar et al, 2019); PLLA with nanoparticles (Raquez et al, 2013); PLLA with biodegradable and biomaterial such as chitosan (Duarte et al, 2010) or cellulose (Ni'mah et al, 2017); and PLLA and plasticizers (Sitompul et al, 2016).…”