Phase behavior of binary blends of high molecular weight diblock copolymers with a low molecular weight triblock
Φόρτωση...
Ημερομηνία
Συγγραφείς
Mickiewicz, R. A.
Ntoukas, E.
Avgeropoulos, A.
Thomas, E. L.
Τίτλος Εφημερίδας
Περιοδικό ISSN
Τίτλος τόμου
Εκδότης
American Chemical Society
Περίληψη
Τύπος
Είδος δημοσίευσης σε συνέδριο
Είδος περιοδικού
peer reviewed
Είδος εκπαιδευτικού υλικού
Όνομα συνεδρίου
Όνομα περιοδικού
Macromolecules
Όνομα βιβλίου
Σειρά βιβλίου
Έκδοση βιβλίου
Συμπληρωματικός/δευτερεύων τίτλος
Περιγραφή
Binary blends of four different high molecular weight poly (styrene-b-isoprene) (SI) diblock copolymers with a lower molecular weight poly(styrene-b-isoprene-b-styrene) (SIS) triblock copolymer were prepared, and their morphology was characterized by transmission electron microscopy and ultra-small-angle X-ray scattering. All the neat block copolymers have nearly symmetric composition and exhibit the lamellar morphology. The SI diblock copolymers had number-average molecular weights, (M) over bar (n), in the range 4.4 x 10(5)-1.3 x 10(6) g/mol and volume fractions of poly(styrene), Phi(PS), in the range 0.43-0.49, and the SIS triblock had a molecular weight of (M) over bar (n) similar to 6.2 x 10(4) g/mol with Phi(PS) = 0.41. The high molecular weight diblock copolymers are very strongly segregating, with interaction parameter values, chi N, in the range 470-1410. A morphological phase diagram in the parameter space of molecular weight ratio (R = M(n)(diblock)/1/2M(n)(triblock)) and blend composition was constructed, with R values in the range between 14 and 43, which are higher than previously reported. The phase diagram revealed a large miscibility gap for the blends, with macrophase separation into two distinct types of microphase-separated domains for weight fractions of SI, w(SI) < 0.9, implying virtually no solubility of the much higher molecular weight diblocks in the lower molecular weight triblock. For certain blend compositions, above R similar to 30, morphological transitions from the lamellar to cylindrical and bicontinuous structures were also observed.
Περιγραφή
Λέξεις-κλειδιά
order-disorder transition, styrene isoprene 2-block, block-copolymers, 3-block copolymers, forming copolymers, strong segregation, parameter space, mixtures, temperature, dependence
Θεματική κατηγορία
Παραπομπή
Σύνδεσμος
<Go to ISI>://000258226200038
http://pubs.acs.org/doi/pdfplus/10.1021/ma801022k
http://pubs.acs.org/doi/pdfplus/10.1021/ma801022k
Γλώσσα
en
Εκδίδον τμήμα/τομέας
Όνομα επιβλέποντος
Εξεταστική επιτροπή
Γενική Περιγραφή / Σχόλια
Ίδρυμα και Σχολή/Τμήμα του υποβάλλοντος
Πανεπιστήμιο Ιωαννίνων. Σχολή Θετικών Επιστημών. Τμήμα Μηχανικών Επιστήμης Υλικών