Structure of crystalline polymers with unbranched long side chains

Abstract

The structure and thermodynamic properties of atactic and isotactic acrylic and methacrylic polymers containing 16–18 carbon atoms in the n‐aliphatic side chains, and of copolymers of hexadecyl acrylate with isopropyl acrylate were studied by means of x‐ray and differential thermal analysis. The crystallization of branched acrylic and methacrylic polymers and of acrylic copolymers proceeds in the form of a hexagonal crystal, regardless of the configuration of the backbone chain. Methods of ordering branched macromolecules are proposed, and the melting points, heats and entropies of fusion determined. The role of flexibility of the backbone chains in ordering and the crystallization processes was determined. In the case of poly(n‐alkyl acrylates) the backbone chain is involved in the crystalline lattice; this is not the case in methacrylates and copolymers of hexadecyl acrylate with isopropyl acrylate. Some similarity was assumed between the structure of biopolymers and synthetic branched polymers.

Surface properties and liquid crystal alignment behavior of poly(2-hydroxyethyl methacrylate) derivatives with alkyl ester side chains

“…From the wide angle values, we found that the side chains of both polymers are tightly packed which has 4.0 Å (and 4.2 Å for fiber samples). It was reported that sidechain polymers having alkyl side groups had a sharp reflection at 4.17 Å when the side chains were long enough to be crystallized in a hexagonal structure [45][46][47][48]. However, bilayered structures with such ordered side chains were not observed on the surfaces of PHEMA#Cs with # 6 13 with shorter alkyl groups.…”

Chiral Molecular Self‐Assembly

“…Similar effects are found in side-chain polymers, where crystallization is found in poly(n-alkyl methacrylates) having 10 or more methylenes in the side chain. 55 In addition, the amide bands of Glc-NC(n)CN-Glc aggregates showed an odd-even effect for longer chain lengths (n > 11), as shown in Figure 5.12b, indicating bolaamphiphiles with even n had weaker hydrogen bonding between the amide groups than those with odd n. Connecting the amide-linked hydrocarbon bridge to the C2 positions of the glucopyranose rings gave a series of bolaamphiphiles that were far less soluble than their C1-linked counterparts discussed above. 56 However, these bolaamphiphiles (15) showed a similar odd-even effect, with twisted fibers forming for n = 10, 12, 14 and amorphous sheets and ribbons observed for n = 11, 13.…”

Bistable electroactive polymer with sharp rigid-to-rubbery phase transition

“…In studying the packing of the long side chains of poly (n-alkyl acrylates), including poly (noctadecyl acrylate), Plate and Shibaev [8] found that the long alkyl chains are extended at right angle to the main chain, while each polymer chain forms a layer structure consisting of rigid 'pivots' (side chains) attached to the main chain and lined up in a regular manner (See Fig 3. inset for poly (n-alkyl acrylates)). Such polymer chains pack in parallel to give a 3D layered ordered structure.…”