Crystal Structure and Morphology of Poly(11-undecalactone) Solution-Grown Single Crystals

Abstract

Solution-grown lamellar single crystals of poly(11-undecalactone) (PUDL) have been prepared in 1-hexanol. The lozenge and hexagonal-shaped single crystals were grown simultaneously, and these crystals gave well-resolved electron diffraction diagrams from which the orthogonal reciprocal lattice with the parameters a* ) 1.346 nm -1 , b* ) 2.004 nm -1 , and γ* ) 90°could be determined. The growth faces of both crystals were considered as mainly {110}, and the average chain-folding direction was parallel to these growth planes, suggesting that the hexagonal crystal has pseudohexagonal symmetry but actual orthogonal packing of the PUDL molecules. The diffraction analysis combined with X-ray and electron diffraction diagrams indicated that PUDL crystallized in the orthorhombic system which had the lattice parameters of a ) 0.743 ( 0.001 nm, b ) 0.499 ( 0.001 nm, and c(chain axis) ) 1.519 ( 0.003 nm. There are two chains per unit cell, which existed in an antiparallel arrangement. The fiber repeat distance is appropriate for an all-trans backbone conformation for the straight stems. Molecular packing of this structure has been studied in detail, taking into account both diffraction data and energy calculations. The setting angles, with respect to a axis, were 59°for the corner and center chains according to intensity measurements and structure factor calculations. A final model was obtained to yield R ) 0.173 with X-ray diffraction data and R ) 0.152 with electron diffraction data. A brief comparison is also made with related polymer structures.

Crystal Structure and Morphology of Poly(16‐hexadecalactone) Chain‐folded Lamellar Crystals

“…The wide‐angle XRD pattern of a neat PHDL sample, shown in Figure 4, is characterized by two strong reflections at 2 θ equal to 21.40° and 23.79° corresponding to d = 0.415 nm and 0.374 nm indexed by (110) and (200), respectively. This is very similar with the diffraction pattern of PUDL, PDDL, and PPDL, as pointed out by previous papers 29–31. In Table 3 the experimental d ‐spacings and intensities of the main reflections are compared with the refined calculated values.…”

“…The refined a and b lattice parameters of PHDL ( m = 15) ( a = 0.746 nm and b = 0.504 nm) are very close to those of polyethylene (PE) ( a = 0.741 nm and b = 0.494 nm),33 PUDL ( m = 10) ( a = 0.743 nm and b = 0.499 nm),29 PDDL ( m = 11) ( a = 0.746 nm and b = 0.500 nm),30 and PPDL ( m = 14) ( a = 0.752 nm and b = 0.502 nm)31 as listed in Table 5, indicating that the lateral cell expansion due to the CO groups does not depend on the number of methylene units in the chain, as previously pointed out by Gazzano et al31 In other words, the effect of the CO group tends to decrease by the large number of methylene units. On the other hand, the c parameters increased with an increase in the number of methylene units in the chain because of the molecular chain having an almost planar zigzag conformation.…”

“…The rotation angles between the plane of the polymer chain and the a axis are 51.5° for PPL,18 61° for P(4HB),20 58° for PVL,21 40° for the fully extended form of PCL,23 48° for PPDL,31 and 41° for PE 33. Recently, we reported that the crystal structures of PUDL29 and PDDL30 have all‐ trans or close to all‐ trans conformations and the setting angle, with respect to the a axis is 59° for PUDL and 43° for PDDL. The stable position of molecular chains with the all‐ trans conformation around the molecular axis seems to be almost same as 40° to 60°.…”

“…Among the biodegradable polyesters of the type (O(CH 2 ) m CO) n , the structures of single crystals have been resolved for poly( β ‐propiolactone) (PPL, m = 2),18 poly(4‐hydroxybutyrate) (P(4HB), m = 3),19,20 poly( δ ‐valerolactone) (PVL, m = 4),21 poly( ε ‐caprolactone) (PCL, m = 5),22–28 poly(11‐undecalactone) (PUDL, m = 10),29 poly(12‐dodecalactone) (PDDL, m = 11),30 and poly(15‐pentadecalactone) (PPDL, m = 14) 31. However, the crystal structure of poly(16‐hexadecalactone) (PHDL, m = 15) has not been studied yet.…”

Star‐Like Poly(N‐isopropylacrylamide) and Poly(ethylene glycol) Copolymers Self‐Arranged in Newfound Single Crystals and Associated Novel Class of Polymer Brush Regimes with V‐Type Tethers

“…Some authors have reported on single crystals of aliphatic polyesters such as poly(ε‐caprolactone) (PCL) . The single crystalline structures of some other biodegradable polyesters including poly(β‐propiolactone), poly(3‐hydroxylbutyrate) (P(3HB)), P(4HB), poly(11‐undecalactone), poly(dvalerolactone), poly(12‐dodecalactone), and poly(15‐pentadecalactone) were also focused. Different types of extracellular polyhydroxybutyrate depolymerases were employed to investigate the degradation of single crystals.…”