Epitaxy-Induced Crystallization of Olefin Block Copolymers

Abstract

The epitaxy forced crystallization behavior of thin film olefin block copolymer (OBC) samples was investigated in the presence of benzoic acid (BA). The investigated OBC samples show apparent phase separation in the melt. However, their dissimilar comonomer difference between hard and soft segments (ΔC8) and block lengths results in different segregation strength, which controls their crystallization behavior. Independent of the crystallization conditions, for both OBCs the BA substrate induces highly oriented and epitaxially grown lamellar crystals. In case of the weakly melt segregated OBC, crystallization always breakout the melt separated phase domains, and crystals are homogeneously distributed in the entire sample. For strongly melt segregated OBC, on the other hand, phase separation is maintained when quenching the samples, and only isolated crystalline domains are formed. However, subsequent annealing of quenched samples, slow cooling from the melt, or isothermal crystallization at low supercoolings on the BA substrate forces crystals breakout the initial confinement. Such crystallization experiments help us better understanding the interplay between molecular architecture, segregation strength, and controlled crystallization conditions on the organization of OBCs.

Liquid–solid transition in mesophase separated olefin multiblock copolymers during crystallization

“…But the initial pathway of crystallization can be quite different depending on connement state in the early stages. [25][26][27] Conned crystallization had also been found during the initial stage of crystallization for OBCs, with the block structures similar to M03 and L02 in this work. 27 Here, the spherulite morphology for OBCs at the critical point of LST is discussed.…”

“…For semicrystalline OBCs, both conned crystallization and breakout crystallization had been found, depending on the competition between the mesophase separation in the melt and crystallization. [20][21][22][23][24][25][26][27] For weakly melt segregated OBCs, crystallization breaks out from the mesophase separated structures. 19,21 For strongly melt segregated OBC, mesophase separation can be maintained and stacks of lamellae are conned within the isolated domains.…”

Investigation of the thin film crystallization of a DNA copolymer hybrid composed of chitosan

“…For instance, nanoporous thin films of about 15–100 nm thickness can be used to control the epitaxial crystallization of Si and NiSi . The morphology of olefin block copolymer structures driven by epitaxy induced crystallization was investigated by Wang and coworkers . In that study, the templates were of periodicities on the scale of tens of nanometres, obtained in a bottom‐up self‐assembly approach, a process directed by block copolymer self‐assembly using inorganic precursors.…”

A Shish-kebab superstructure in low-crystallinity elastomer nanocomposites: Morphology regulation and load-transfer

“…1,2 With densely research in mesophase separation, block architecture and elastomeric properties, OBC affirmably exhibits different microdomain structure, network effectiveness and mechanical properties from ORCs. [3][4][5][6][7][8][9] Presenting large industrial potential, OBCs still have shortcomings such as unsatisfying tensile strength and Young's modulus due to their low crystallinity. Yet, no work on the morphology and properties of filled OBC systems has been reported.…”