Structural arrangement of crystalline/amorphous phases of polyethylene‐block‐polystyrene copolymer as induced by orientation techniques

Abstract

ABSTRACT.Polyethylene-block-polystyrene (PE-block-PS) copolymer film having bicontinuous crystalline/amorphous phases were tensile-drawn under various conditions for structural arrangement of these phases. When a draw was made below melting temperature of PE crystalline phase (95 o C), the bicontinuous structure was gradually destroyed with increasing strain, due to the lower ductility of PS having glass-transition temperature around 100 o C. Correspondingly, the necking phenomenon was clearly recognizable during draw. In contrast, a draw near melting temperature of PE crystalline phase gave the less orientation of PE phases, resulting in homogeneous deformation with the lower draw stress.These results indicated that the modification of the lower ductility of PS was required for the effective orientation of these phases. Here, a solvent swelling technique was applied to improve PS deformability even below its glass-transition temperature. Tensile drawing after such treatment could successfully induce the orientation of both crystalline/amorphous phases. A transition from necking to homogenous deformation was also observed in stress/strain behavior.

Nanowrinkled and Nanoporous Polyethylene Membranes Via Entanglement Arrangement Control

“…Solid‐state relaxation after drawing of UHMW‐PE also enables a control of molecular rearrangement, resulting in a periodic arrangement composed of lamellar crystals and amorphous layers 14. Such ordered‐phase morphology is quite similar to microphase separation of block copolymers 15–21. Here, the former lamellar thickness of 30 nm coincides with the segmental length corresponding to the critical MW between entanglements (3600 Da) for PE,22 which play a role similar to that of molecular linking points of the block copolymer chain, in terms of the boundary determining the phase separation ( Figure ).…”

“…Here, it should be noted that characteristic morphologies of block copolymer are available for the preparation of functional materials. We have obtained bicontinuous networks of microphase separation for diblock copolymers containing both crystalline and amorphous segments by varying the crystallization conditions 17, 18, 21. Further selective sulfonation or etching of amorphous components gave a electrolyte or nanoporous membrane supported by the surviving counter crystalline PE network.…”

Nanoporous morphology control of polyethylene membranes by block copolymer blends

“…The base copolymer is the same material used in our previous studies. 26,27,29,31 The chemical agents used for preparing the nanoporous membranes were p-xylene (98% purity) and fuming nitric acid (FNA) (97% purity) supplied from Wako Chemical in Japan. The D-glucose and bovine serum albumin (BSA) solutions for permeation tests were purchased from Aldrich in the USA.…”

“…Indeed, diblock copolymer composed of polyethylene (PE) and polystyrene (PS), PE-b-PS, exhibits the desirable bicontinuous crystalline/amorphous phase separation when it is crystallized under optimum conditions. 26,27 Selectively removing the amorphous phase of both PE and PS components through acid etching treatment yielded a characteristic network morphology of nanopores passing through the membrane thickness. The residual crystalline PE networks are the supporting component for this nanoporous membrane, thus it is robust and exible.…”

Isothermal Crystallization Behavior of Polyethylene/Polystyrene Block Copolymer Estimated by Deconvolution Analysis of Differential Scanning Calorimetry Profiles

“…These results indicated that the deconvolution analysis of DSC profiles is useful for evaluating the constitution of crystalline domains in the bicontinuous crystalline/amorphous structure of isothermally crystallized PE-b-PS. KEY WORDS Polyethylene /Polystyrene Block Copolymer / Isothermal Crystallization / Melting / DSC Measurement / Deconvolution Analysis / (Received September 6, 2018: Accepted November 5, 2018: Advance Publication December 18,2018) [ Kobunshi Ronbunshu, 76, 150-156 (2019)] ©2019, The Society of Polymer Science, Japan…”