Block Copolymers with Photocleavable Junctions E. Bryan Coughlin University of Massachusetts Amherst S MgBr CS 2
O
click O n Fw= 2 K or 5 K
n N3
N N N
bis(4,4'-cyanovaleric acid) Ethyl acetate, 60 °C 18 hrs
S
OH
Br
NO2
DMF/K2CO3 60 oC, 24 h 60 %
HNBA
S
S
CN OH
S
CCTA
O
O
O
OH NO2
S
SH Water:diethyl ether
toluene
HO
S KI/I2
10 (1 eq)
CCTA (1.1 eq) DCC (1 eq), DMAP (0.1 eq) rt, overnight 83%
O
S
O NO2
CN
S
11
O O
O NO2
S CN
S
PEO-hv-CTA
OR first get PS-ONB, then "click" make PEO-ONB-PS .
A spectrum of PS-hv-PEO materials were prepared with a 5 kDa PEO block and various PS blocks as noted in the table. Good molecular weight control and low Đ were observed in these systems.
A) Height-contrast and B) phase contrast AFM images (1μm x 1 μm) of 5 kDa PEO – hv – 24 kDa PS BCP films after annealing 2.5 hours in THF:water atmosphere. 2D Fourier transform inset shows long-range ordering produced by solvent annealing.
