Surface enrichment and evaporation in a polymer mixture of long and short chains

Conference · Thu Nov 30 23:00:00 EST 1989

OSTI ID:6963514

Composto, R J; Stein, R S ^[1]; Felcher, G P; Mansour, A; Karim, A ^[2]

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1. Massachusetts Univ., Amherst, MA (USA). Polymer Research Inst.
2. Argonne National Lab., IL (USA)

Neutron reflectivity has been used to determine the concentration profile at the vacuum-polymer interface for a two polymer blend. To quantify surface enrichment and evaporation due to differences in chain length, we have measured the reflectivity of a mixture of short deuterated and long protonated polystyrene chains (DPS PS), with a weight fraction of 0.5. When a mixture of DPS and PS chains of molecular weight 720 and 910k respectively were annealed, a small but measurable increase in asymptotic reflectivity occurred, coupled with a decrease of film thickness and scattering length density. This is indicative of surface enrichment and evaporation of the light chains (DPS). Ellipsometry studies confirmed that the short chains evaporated and its rate was established as a function of the temperature. Upon increasing the DPS molecular weight to 9600, the enrichment becomes considerably greater whilst the evaporation becomes negligible. 3 figs.

• Research Organization: Argonne National Lab., IL (USA)
• Sponsoring Organization: DOE/ER
• DOE Contract Number: W-31109-ENG-38
• OSTI ID: 6963514
• Report Number(s): CONF-891119-124; ON: DE90010073
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360602* -- Other Materials-- Structure & Phase Studies
360603 -- Materials-- Properties
BARYONS
DIMENSIONS
ELEMENTARY PARTICLES
ENRICHMENT
EVAPORATION
FERMIONS
HADRONS
MATERIALS
MOLECULAR WEIGHT
NEUTRONS
NUCLEONS
OPTICAL PROPERTIES
ORGANIC COMPOUNDS
ORGANIC POLYMERS
PETROCHEMICALS
PETROLEUM PRODUCTS
PHASE TRANSFORMATIONS
PHYSICAL PROPERTIES
PLASTICS
POLYMERS
POLYOLEFINS
POLYSTYRENE
POLYVINYLS
REFLECTIVITY
SURFACE PROPERTIES
SYNTHETIC MATERIALS
THICKNESS