Microphase separated structures in the solid and molten states of double-crystal graft copolymers of polyethylene and poly(ethylene oxide)

Journal Article · Tue Aug 26 04:00:00 EDT 2008 · Polymer

DOI:https://doi.org/10.1016/j.polymer.2008.05.012· OSTI ID:1006694

Mark, P R; Murthy, N S; Weigand, S; Breitenkamp, K; Kade, M; Emrick, T ^[1]

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1. Vermont

Transitions from one microphase separated structure in the solid state to a different one in the molten state in polyethylene-graft-poly(ethylene oxide) copolymers, PE-g-PEO, were investigated by variable temperature X-ray scattering measurements and thermal analyses. Small-angle X-ray scattering patterns from polymers with PEO grafts with 25, 50 and 100 ethylene oxide (EO) units show that the polymer passes through three distinct structures at {approx}10 nm length scales with increase in temperature (T): lamellar structures of PE and PEO at T < T{sub m}{sup PEO}, PE lamellae surrounded by molten PEO at T{sub m}{sup PEO} < T < T{sub m}{sup PE}, and microphase separated structures at T > T{sub m}{sup PE} when both PE and PEO are molten (T{sub m} refers to the melting temperature). These phase transformations also occur during cooling but with hysteresis. Crystalline phases of PEO side chains and PE main chains could be identified in the wide-angle X-ray diffraction profiles indicating that the PE backbone and PEO grafts crystallize into separate domains, especially with longer grafted chains (50 and 100 units). At EO segment lengths >50, PEO shows the expected increase in melting and crystallization temperatures with the increase in the grafted chain length. PE does not affect T{sub m}{sup PEO} but does decrease the onset of crystallization upon cooling. PEO grafts result in fractionation of PE, decrease the melting point of PE and increase the undercooling for the onset of crystallization of PE.

• Research Organization: Advanced Photon Source (APS), Argonne National Laboratory (ANL), Argonne, IL (US)
• Sponsoring Organization: USDOE
• OSTI ID: 1006694
• Journal Information: Polymer, Journal Name: Polymer Journal Issue: (13-14) ; 06, 2008 Vol. 49; ISSN 0032-3861; ISSN POLMAG
• Country of Publication: United States
• Language: ENGLISH

Related Subjects

36 MATERIALS SCIENCE
COOLING
COPOLYMERS
CRYSTALLIZATION
ETHYLENE
FRACTIONATION
GRAFT POLYMERS
HYSTERESIS
LAMELLAE
LENGTH
MELTING
MELTING POINTS
OXIDES
PHASE TRANSFORMATIONS
PLASMA SWITCHES
POLYETHYLENES
POLYMERS
SCATTERING
SOLIDS
UNITS
X-RAY DIFFRACTION