Segregation of chain ends to polymer melt surfaces and interfaces

Journal Article · Mon Feb 01 04:00:00 UTC 1993 · Macromolecules; (United States)

DOI:https://doi.org/10.1021/ma00055a026· OSTI ID:6486365

Zhao, W; Zhao, X; Rafailovich, M H; Sokolov, J ^[1]; Composto, R J ^[2]; Smith, S D; Satkowski, M ^[3]; Russell, T P ^[4]; Dozier, W D ^[5]; Mansfield, T ^[6]

---

1. Queens Coll., Flushing, NY (United States)
2. Univ. of Pennsylvania, Philadelphia (United States)
3. Procter and Gamble Co., Cincinnati, OH (United States)
4. IBM Research Div., San Jose, CA (United States)
5. Argonne National Lab., IL (United States)
6. Univ. of Massachusetts, Amherst (United States)

The conformation of polymer chains in the melt near an impenetrable boundary has recently been studied by molecular dynamics and off-lattice Monte Carlo simulations. Both types of calculations show an enhancement of the chain end density within a distance of approximately two polymer segment lengths of the interface relative to the bulk. In the absence of preferential interactions between monomers and the interface, the segregation arises from minimizing the loss of conformational entropy near an impenetrable boundary; i.e., by positioning an end near the surface, only one unit rather than two is reflected. In order to obtain an experimental measure of this effect, monodisperse polystyrene (PS) chains of molecular weight 63 000 with short blocks of deuterated polystyrene (dPS) at each end were prepared. The block length was kept as short as possible, while yet producing sufficient neutron scattering contrast in order to minimize any preferential surface segregation due to isotopic effects. The synthesis was carried out via living anionic polymerization of a purified styrene monomer in cyclohexane at 60 C, utilizing sec-butyllithium as the initiator. The process was terminated using degassed methanol.

• DOE Contract Number: W-31109-ENG-38
• OSTI ID: 6486365
• Journal Information: Macromolecules; (United States), Journal Name: Macromolecules; (United States) Vol. 26:3; ISSN MAMOBX; ISSN 0024-9297
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360602* -- Other Materials-- Structure & Phase Studies
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400202 -- Isotope Effects
Isotope Exchange
& Isotope Separation
BARYONS
ELEMENTARY PARTICLES
ENTROPY
FERMIONS
HADRONS
INTERFACES
ISOTOPE EFFECTS
MOLECULAR STRUCTURE
MOLECULAR WEIGHT
NEUTRONS
NUCLEONS
PHYSICAL PROPERTIES
POLYMERS
SCATTERING
SEGREGATION
THERMODYNAMIC PROPERTIES