Studies on the self‐assembly of neat DBS and DBS/PPG organogels

Abstract

The self-assembly behavior of neat 1,3:2,4-dibenzylidene-D-sorbitol (DBS) and DBS/poly(propylene glycol) (PPG) organogels has been investigated by scanning electron microscopy, polarizing optical microscopy, and rheological measurements. DBS molecules are capable of selforganizing into fibrils and exhibit the birefringent spherulitic textures during cooling from the melt. On the other hand, DBS can self-assemble into a fibrillar network in PPG to produce organogels. DBS/PPG organogels also reveal a spherulite-like morphology. When a small amount of DBS is dispersed into a PPG matrix, we find that the spherulite sizes are much smaller than those of neat DBS. This is because the dilution of DBS causes DBS to self-assemble in PPG at a lower temperature. Therefore, more nucleation sites and smaller spherulite sizes are found in the DBS/PPG organogel system. The rheological measurements demonstrate that the elastic modulus (G 0 ) in DBS/PPG organogels increases as the DBS concentration increases. However, the increase in G 0 is less obvious, as the DBS content exceeds 3 wt %. suggesting that the DBS networks become saturated. Also, it is found that these organogels require a certain period of time to reach thermodynamic equilibrium, depending on DBS concentrations.

Preparation of polyethylene microporous membranes with high water permeability from thermally induced multiple phase transitions

“…Liu et al [29,30] suggested using the dibenzylidene sorbitol (DBS) to control the pore structure in polyethylene/liquid paraffin system. In fact, DBS is widely used as nucleation agent in the polymer system [31][32][33], which can strongly interact and self-assemble to form a physical gel into fibril network in various matrices [34][35][36]. The self-assembly of DBS depends on the solvent polarity, DBS concentration, temperature and time [37].…”

Transparent semi‐crystalline polymeric materials and their nanocomposites: A review

“…The introduction of EVOH with excellent water vapor barrier properties broadens the application of transparent PLA/EVOH especially in the packaging field. [22] F I G U R E 1 Chemical structures of, A, DBS, [18] B, DMDBS (the darker atoms are carbon, light gray atoms are oxygen and the white atoms are hydrogen), [19] C, N,N 0 ,N 00 -tris-isopentyl-1,3,5-benzene-tricarboxamide [20] and, E, PA PACM12. Optical performance of, D, iPP/DMDBS containing different amount of DMDBS, [21] F, PLA, EVOH, their incompatible blends (EP and EPA) as well as compatibilized blends (EPAZn) [22] and, G, uniaxially and biaxially stretched PET/MXD6 blends with 10 wt% MXD6 as a function of isophthalate content for modifying PET matrix [23] [Color figure can be viewed at wileyonlinelibrary.com]…”

Interactions between sorbitol‐type nucleator and additives for polypropylene

“…[5,31] Selfassembled DBS fibrils from the melt have been shown to organize in spherulitic morphologies. [32,33] To our knowledge however the self-assembly process of neat TBPMN upon cooling has not been monitored directly. [32,34] As shown in Figure 5, after melting TBPMN at 240 C under N 2 atmosphere, the self-assembly of the compound was monitored by optical microscopy under inert atmosphere.…”