Structure and mechanical effects of random copolymer layers at polymer interfaces
- IBM Almaden Research Center, San Jose, CA (United States); and others
Chemically different polymers are frequently immiscible in each other because the large size of the individual molecules causes the mixing entropy to be low. The interfaces between polymers are normally relatively sharp ({approximately}20-30{Angstrom}) on the scale of a polymer chain. However polymer materials gain their mechanical strength from the entanglement between chains. Significant entanglement at an interface can only occur if the interface width is greater that the distance between entanglements which is typically 40-80{Angstrom}. It is therefore not surprising that polymer interfaces are frequently weak. The most common way to increase the strength or toughness of a polymer interface is to use some specific polymer chains that can connect across the interface. These connecting chains can be formed using one of a number of techniques. Sometimes they are formed in-situ by an interfacial chemical reaction that connects a chain of one of the materials to a chain of the other. Alternatively the connecting chains can be preformed copolymers which are placed at the interface or allowed to diffuse to the interface during processing. The aim of the work presented here is to examine the effects of composition of a P(S{sub f}-MMA{sub 1{minus}f}) copolymer, where f refers to the fraction of PS, on its effectiveness as a coupling agent between PS and PMMA homopolymers. The mechanical results are compared with neutron reflection measurements of the width of the interfaces between the copolymers and the two homopolymers.
- OSTI ID:
- 441475
- Report Number(s):
- CONF-960214--
- Country of Publication:
- United States
- Language:
- English
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