Noncovalent polymerization and assembly in water promoted by thermodynamic incompatibility.
This work studies the phase separations between polymers and a small molecule in a common aqueous solution that do not have well-defined hydrophobic-hydrophilic separation. In addition to poly(acrylamide) (PAAm) and poly(vinyl alcohol) (PVA), poly(vinyl pyrrolidone) (PVP) also promotes liquid crystal (LC) droplet formation by disodium cromoglycate (5'DSCG) solvated in water. In the presence of these polymers, the concentration of 5'DSCG needed for forming LC droplets is substantially lower than that needed for forming an LC phase by 5'DSCG alone. To define the concentration ranges that 5'DSCG molecules form liquid crystals (either as droplets or as an isotropic-LC mixture), we constructed ternary phase diagrams for 5'DSCG, water, and a polymer - PVA, PVP, or PAAm. We discovered that PAAm with high molecular weight promotes LC droplet formation by 5'DSCG more effectively than PAAm with low molecular weight. At the same weight percentage, long-chain PAAm can cause 5'DSCG to form LC droplets in water, whereas short-chain PAAm does not. Poly(vinyl pyrrolidone) (PVP), which has functional groups that are more dissimilar to 5'DSCG than PVA and PAAm, promotes LC droplet formation by 5'DSCG more effectively than either of the other two polymers. Additionally, small angle neutron scattering data revealed that the assembly structure of 5'DSCG promoted by the presence of PVA is similar to the thread structure formed by 5'DSCG alone. Together, these results reveal how noncovalent polymerization can be promoted by mixing thermodynamically incompatible molecules and elucidate the basic knowledge of nonamphiphilic colloidal science.
Simon
Karen A
KA
Department of Chemistry, Syracuse Biomaterials Institute, Syracuse University, Syracuse, New York 13244, USA.
Sejwal
Preeti
P
Falcone
Eric R
ER
Burton
Erik A
EA
Yang
Sijie
S
Prashar
Deepali
D
Bandyopadhyay
Debjyoti
D
Narasimhan
Sri Kamesh
SK
Varghese
Nisha
N
Gobalasingham
Nemal S
NS
Reese
Jason B
JB
Luk
Yan-Yeung
YY
D004205:Cromolyn Sodium / Q000737:chemistry; D003460:Crystallization; D057927:Hydrophobic and Hydrophilic Interactions; D050866:Liquid Crystals / Q000737:chemistry; D015394:Molecular Structure; D011108:Polymers / Q000737:chemistry*; D053838:Scattering, Small Angle; D012996:Solutions; D013816:Thermodynamics; D014867:Water / Q000737:chemistry*
D011108:Polymers; D012996:Solutions; D014867:Water; D004205:Cromolyn Sodium