Competitive reaction of phthalic anhydride end- and mid-functional PMMAs with amine end-functional PS (PS-NH2) was conducted to measure the coupling rate ratio, kb/kg, for block and graft copolymers formation. The functional PMMAs were fluorescently labeled with 7-nitrobenz-2-oxa-1,3-diazole (NBD) and anthracene for end and mid, respectively. We measured conversions to block and graft copolymers at characteristic excitation and emission wavelengths for NBD and anthracene using a fluorescence detector coupled with GPC. Mid-functional PMMA experiences more steric hindrance due to the chain giving kb/kg of ∼ 3 in solution. For reaction at a static interface, kb/kg increased to ∼ 5 because of the preference of chain ends to locate at the interface at equilibrium. However, kb/kg for blends prepared in a mixer was almost same as that for the solution reaction. The external flow is considered to be the main cause for this result.
|Original language||English (US)|
|Number of pages||5|
|State||Published - 2003|
|Event||61st Annual Technical Conference ANTEC 2003 - Nashville, TN, United States|
Duration: May 4 2003 → May 8 2003
|Other||61st Annual Technical Conference ANTEC 2003|
|Period||5/4/03 → 5/8/03|
Bibliographical noteFunding Information:
The authors thank Jianbin Zhang for help in completing this manuscript. This research has been supported by grants from the MRSEC program of the National Science Foundation under Award Number DMR-0212302, IPRIME (the Industrial Partnership for Research in Interfacial and Materials Engineering at the University of Minnesota) and the Dow Chemical Company.