pH-controlled polymer surface segregation.
A new approach to promoting and controlling polymer surface functionalization with acidic or basic polar functional groups is demonstrated and evaluated. Blended polymer films were annealed under pH-buffered conditions, and polar end-functional groups were found to promote surface segregation of the functional polymers. Surface segregation of carboxylic acid (COOH)-functionalized polystyrene increases dramatically with increasing pH from 1.9 to 9.4, whereas the opposite behavior is seen for amine (NH2)-functionalized polystyrene. Neutron reflectometry and nuclear reaction analysis were used to obtain surface excess values for the functional polymers. Subsequent SCFT analysis of the composition versus depth profiles indicates that the affinity of each functional group for the polymer surface changes by about 3k(B)T over this pH range.
Department of Chemistry, Durham University, Science Site, Durham DH1 3LE, UK. R.L.Thompson@dur.ac.uk
Richard L
RL
Thompson
Sarah J
SJ
Hardman
Lian R
LR
Hutchings
Amilcar Pillay
AP
Narrainen
Robert M
RM
Dalgliesh
D000588:Amines / Q000737:chemistry; D002264:Carboxylic Acids / Q000737:chemistry*; D002621:Chemistry / Q000379:methods*; D003998:Dicarboxylic Acids / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007477:Ions; D008567:Membranes, Artificial; D015233:Models, Statistical; D009502:Neutrons; D011108:Polymers / Q000737:chemistry*; D011137:Polystyrenes / Q000737:chemistry; D011312:Pressure; D013499:Surface Properties; D013500:Surface Tension; D013696:Temperature
D000588:Amines; D002264:Carboxylic Acids; D003998:Dicarboxylic Acids; D007477:Ions; D008567:Membranes, Artificial; D011108:Polymers; D011137:Polystyrenes