Calculation of Lamellar Thickness in a Diblock Copolymer, One of Whose Components Is Crystalline

Abstract

We treat a diblock copolymer of lamellar morphology where one of the blocks is amorphous and one is crystalline (amphiphilic copolymer). The proposed models allow for the stretching of polymer chains, the change in packing entropy arising from changes in orientation of bonds, and the space-filling properties of the chains. Formulas are given for the thickness of the amorphous and crystalline lamellae, Za and Zc, as functions of the lengths of the blocks, ra and rc, the surface and fold free energies, a, and at, the temperature T, the amount of solvent in the amorphous phase v0 = 1vz, and the densities pa and pc (pa = vzp0). We have Za = ra2/3(<78 + vtpjV'HSkTpjW and Zc = r^c, + *,Pc)1/3/Pcra1/3(3m1/3.

Significant increase in the melting temperature of poly(ɛ-caprolactone) blocks confined in the crystallized lamellar morphology of poly(ɛ-caprolactone)-block-polyethylene copolymers

“…That is, the conformational entropy is depressed for such amorphous blocks as compared with equivalent blocks without any spatial confinement. This chain stretching of amorphous blocks in the crystallized lamellar morphology of crystalline-amorphous diblock copolymers is theoretically predicted 6,7 and also experimentally verified. [8][9][10] The crystalline-crystalline diblock copolymers with separate melting temperatures T m,1 and T m,2 (T m,1 cT m,2 ) behave as crystalline-amorphous diblocks at temperatures higher than T m,2 .…”

“…From the equilibrium melting temperature T m 1 (¼342 K) 37 and the heat of fusion for perfect PCL crystals DH m 1 (¼135 J g À1 ), 25 we find l from DT m throughequations (6) and (7). Figure 6 shows dS for 1 g PCL blocks and l for one PCL block plotted against f PCL , where dS increases steadily with increasing f PCL , suggesting that the conformational entropy of PCL blocks confined in the PE lamellar morphology is considerably reduced when it is compared with that in PCL-b-PB.…”

The polymer in a cone - A model for the surface free energy of polymer crystal with emergent cilia

“…The major approximation in the above is the assumption that the interference of one cilia with the rest of its neighbors may be estimated by containing it in the fraction of vol· ume available to it in the sphere (a cone of angle e). The justification for this assumption will be amplified in a later paper [12]. For now let us say this approach is simi· lar to van der Waals theory of the liquid state where the reduction in number of configurations available to a molecule is accounted for by the condition that the volume available to that molecule of the liquid is very closely its molecular specific volume.…”

“…This assumption is made due to our inability to solve the nc chain problem. A partial justification for such a procedure is given in a subsequent paper [12].…”

Morphology of Highly Textured E/EP Diblock Copolymers

“…Several theories [24,25] have been proposed to describe the equilibrium morphology of lamellar semicrystalline diblock copolymers systems. Whitmore and Noolandi …”