Phase Behavior of Polystyrene-block-Poly(n-butyl-ran-n-hexyl) Methacrylate Copolymers

The phase behavior of symmetric polystyrene-block-poly(n-butyl-ran-n-hexyl) methacrylate copolymers (PS-b-Pn(B-r-H)MA) with various molecular weights was investigated by small-angle X-ray scattering (SAXS), rheometry, polarized optical microscopy (POM), and static birefringence. PS-b-PnBMA exhibited...

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Bibliographic Details
Published in:Macromolecules 2008-09, Vol.41 (18), p.6793-6799
Main Authors: Moon, Hong Chul, Han, Sung Hyun, Kim, Jin Kon, Li, Guang Hua, Cho, Junhan
Format: Article
Language:English
Subjects:
Applied sciences
Exact sciences and technology
Organic polymers
Physicochemistry of polymers
Properties and characterization
Thermal and thermodynamic properties
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Summary:The phase behavior of symmetric polystyrene-block-poly(n-butyl-ran-n-hexyl) methacrylate copolymers (PS-b-Pn(B-r-H)MA) with various molecular weights was investigated by small-angle X-ray scattering (SAXS), rheometry, polarized optical microscopy (POM), and static birefringence. PS-b-PnBMA exhibited a lower disorder-to-order transition (LDOT), whereas PS-b-PnHMA exhibited an order-to-disorder transition (UODT). However, when a random copolymer of Pn(B-r-H)MA was used as one of the blocks, PS-b-Pn(B-r-H)MA showed closed-loop phase behavior having both LDOT and UODT, which was seen in PS-b-poly(n-pentyl methacrylate) copolymer, when the total molecular weight was judiciously controlled. The phase behavior change by including a random copolymer was explained by an argument based on a compressible random phase approximation. We also found that the pressure coefficient of both transition temperatures of PS-b-Pn(B-r-H)MA was much larger than that of neat PS-b-PnBMA and PS-b-PnHMA.
ISSN:0024-9297
1520-5835
DOI:10.1021/ma800645u