Novel network morphology of poly(p‐oxybenzoyl)

Abstract

Polymerization of 4‐acetoxybenzoic acid (ABA) with 3,5‐diacetoxybenzoic acid (DABA) was examined to control the morphology of poly(p‐oxybenzoyl) (POB). Polymerizations were carried out at a concentration of 1.0% in an aromatic solvent Therm S‐1000® (mixture of dibenzyltoluene) at 320 °C. Polymerization of ABA yielded the POB fibrillar crystals, but the polymerization with DABA at a concentration in the feed (χf) of 0.10–0.15 afforded novel network structures comprised of spheres connected by fibrillar crystals. The diameter of the spheres prepared at χf of 0.15, which were 0.7 and 5.0 μm, showed bimodality. The network distance, fibril length, and fibril width were 6.1, 2.6, and 0.1 μm, respectively. They possessed high crystallinity. The network structure was formed as follows. Co‐oligomers were first precipitated in the beginning of the polymerization by liquid–liquid phase separation to form the microdroplets. The fibrillar crystals were formed in the coalesced spheres by the crystallization of oligomers induced by the increase of molecular weight. The fibrillar crystals connecting the spheres gradually appeared owing to the shrinkage of the spheres. The fibrillar crystals grew from the surface of the spheres with the crystallization of homo‐oligomers of 4‐oxybenzoyl units, and finally the network structure was completed. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1624–1634, 2005

Morphology Control of Aromatic Polymers in Concert with Polymerization

“…The stirring effect on the morphology of POC was investigated and the morphology was drastically changed from spheres to rod-like crystals having a twisted structure. 80 This result provides a new morphology control procedure by hydrodynamically induced crystallization.…”

“…82,83 The polymerization of ABA and 3,5-diacetoxybenzoic acid (DABA) at a molar ratio of DABA in the feed of 0.05-0.20 yielded the microspheres having needlelike crystals on the surface as shown in Figure 9b. The diameter of the microspheres was in the range of 3.4-1.6 mm and the length of the needle-like crystals was 3.2-0.3 mm.…”

Morphological diversity and nanofiber networks of poly(p‐oxybenzoyl) generated by phase separation during copolymerization

“…When the N COOH value is two, the phase separation mode is changed from the liquid−liquid phase separation to the crystallization during polymerization. One possibility for the formation mechanism of the network had been already proposed 26. Oligomers containing 3,5‐dioxybenzoyl moiety corresponding to DABA residue are precipitated via liquid–liquid phase separation to form the microdroplets in the initial stage of the polymerization.…”

“…Next the crystallization of oligomers started on the surface of the already formed microspheres after the middle stage of the polymerization, resulting in the formation of the needle‐like crystals on the surface of the microspheres. Networks of spheres had been prepared by the polymerization of ABA with DABA, in which the large spheres connected each other by the fibrillar crystals 26…”

Microscopy study of powder‐to‐powder polycondensation of DL‐1,3‐bis(hydroxyphenylmethyl)benzene

“…The fibrous growth of nylon‐6 was observed on 6‐aminocapric acid crystals with scanning electron microscopy (SEM), and it was proposed that the monomer could be transported through the vapor phase to the propagating polymer 13. A variety of shapes of aromatic polyester whiskers were found to be formed by the reaction‐induced crystallization of the oligomers and the subsequent solid‐state postpolymerization 14. A higher polymerizability of L ‐leucine NCA in comparison with L ‐alanine NCA was demonstrated by an SEM view, which showed a lamellar structure, suggesting oriented growth of poly( L ‐leucine) in the monomer crystal 9.…”