Side-Chain Crystallization in Alkyl-Substituted Semiflexible Polymers

Abstract

A series of comblike semiflexible polymers, in which the alkyl side chains were located nonsymmetrically on the ring, were synthesized by reacting hydroxypropylcellulose (HPC) with hexyl, octyl, dodecyl, and octadecyl isocyanates. Side-chain melting was observed in DSC experiments for polymers with 12 and 18 carbons in the pendant groups (C12HPC and C18HPC). Wide-angle X-ray (WAXS) studies indicated that the alkyl groups in C12HPC crystallized in a form similar to the βT crystal of hydrocarbons but multiple crystalline forms coexisted in C18HPC. However, reorganization of the alkyl side chains was observed as the polymers underwent thermal transitions. A better packing of the alkyl side chains could be induced by shearing the samples in the molten state followed immediately by slow cooling. Quenching and annealing studies suggested that side-chain crystallization and reorganization could influence the packing of the semiflexible backbone. The interplay between the main chain and the side chain in order development is described.

Crystalline Polymorphism of Alkyl Chains in Supramolecular Complexes of Polyethyleneimine with Octadecanoic Acid

“…Data in the literatures give a main characteristic diffraction of hexagonal d (110) spacing of 4.17 , two main characteristic diffraction of orthorhombic packing corresponding to spacing of 4.10 (d 110 ) and 3.7 (d 200 ), and main characteristic diffraction of triclinic packing corresponding to spacing of 4.5 (d 001 ), 3.8 (d 200 ) and 3.6 (d 201 ). [25,26] Figure 3 shows the WAXS profiles of the complexes. The interplanar spacing of the corresponding diffraction peaks of each sample are summarized in Table 3.…”

“…For P4VP(PDP) x , the orthorhombic crystal modification appears until x up to 2, [1] confirming that no "zipper mechanism" of binding mode and free OA separation from the rest of complexes occurs at low content of OA. It is interesting to note that an additional hexagonal diffraction peak corresponding to a spacing of 2.47 appears when x f 2.48, [25,26] and the diffraction intensity corresponding to a spacing of 3.67 increases as x increases, illustrating the combination of the hexagonal and orthorhombic packing when x f 2.48. Such result demonstrates that the fraction of these two kinds of ordered packing changes gradually, accurately speaking, the hexagonal structure keeps relative constant, and the increased part of alkyl chains of OA separates to form the orthorhombic and monoclinic array, which is different from that of the P4VP(PDP) x complexes investigated by G. ten Brinke group.…”

Soluble, photoluminescent, ionic polymers with 2,6-bisphenyl-4-anthracenyl-N-hexadecylpyridinium tetrafluoroborate segments

“…A weak and quite broad endotherm at 123°C, which disappeared completely during the second heating, was assigned to the evaporation of residual water. The DSC thermogram of polyester SA displayed during the first heating scan a weak endotherm at 71°C attributable to the side chains melting 31 and large endotherms at 93°C (melting of polymer) and 130°C (formation of isotropic melt). Polyether TA1 exhibited a more complex thermal behavior with endotherms at 93, 117 (melting of polymer), 210, 240, and 245°C.…”

Preparation and Characterisation of Hydrophobically Modified Hydroxypropylcellulose: Side‐Chain Crystallisation

“…For instance, the reaction of HPC with alkyl isocyanates of different chain length has been reported. [5] Similarly, poly(vinyl alcohol) has been modified by substitution with different reagents. [4,6,7] In general, therefore, these modifications involve the introduction of long or relatively long alkyl-terminated side chains, leading to particular cases of comb-type polymers.…”