Synthesis of Optically Active Helical Poly(2-methoxystyrene). Enhancement of HeLa and Osteoblast Cell Growth on Optically Active Helical Poly(2-methoxystyrene) Surfaces

Abstract

Poly(2-methoxystyrene)s (P2MS) were synthesized using n-BuLi in THF and toluene at various temperatures. At -20 degrees C and higher temperatures, toluene was an effective polymerization solvent for synthesizing poly(2-methoxystyrene). Under these conditions, polymers with good yields and reasonable molecular weight distributions were obtained. Polymers synthesized under all conditions were isotactic; the most highly isotactic polymer was obtained in toluene at -20 degrees C. The m (isotactic dyad) content of the polymers synthesized in toluene at 0 degrees C and -20 degrees C was 0.65 and 0.74, respectively. Optically active helical (+) and (-) P2MS were synthesized by asymmetric polymerization utilizing (+) or (-) [2,3-dimethoxy1,4(dimethylamino)butane] (DDB)/tolyl lithium initiating complex in toluene. Asymmetric polymerizations were also carried out at 0 degrees C to synthesize optically active polymers. The optical rotations of the polymers were found to be dynamic and reversible, strongly suggesting contribution of the chiral higher ordered structure to the overall optical rotation. Geometry optimization carried out using various force fields such as MM+, AMBER and CHARMM suggests that isotactic P2MS form low energy stable helical conformations. HeLa cells showed better growth on surfaces prepared using chiral polymers compared to the surfaces prepared with achiral polymers. Similarly, chiral P2MS surfaces were also more effective as supports for mouse and human osteoblast cells. The cell attachment and growth data demonstrate that chiral P2MS surfaces were better supports compared to achiral P2MS surfaces. Atomic force microscopy (AFM) studies on surfaces prepared using chiral poly(2-methoxystyrene) showed more discrete topography features compared to surfaces prepared with achiral polymers. Thus, the surface topography may play a role in determining polymer-cell interactions.

Phase behaviors of side chain liquid crystalline block copolymers

“…On the other hand, the interfacial/surface energy becomes unfavorable. 53,54 Additionally, at a constant N C , as the N A increases, the phase transition experiences the progress of S A / C A / G A / L / G C . Originally, the volume fraction of A blocks was too low, so that C blocks were inclined to form the matrix and the S A , C A and G A phases are formed.…”

Synthesis and Stereospecific Polymerization of a Novel Bulky Styrene Derivative

“…This is usually achieved by utilizing steric congestion substituents, which restrict the free rotations around the σ-bonds linking main chain carbon atoms. ,, The attachment of large pendant groups to polymer main chain increases the internal rotation barrier and has led to numerous helical bulky poly­(meth)­acrylates and poly­(meth)­acrylamides. − Despite these remarkable successes, most of the efforts to obtain optically active helical polystyrene derivatives end with undesired results. Isotactic-rich poly­(3-methyl-4-vinyl­pyridine), poly­(2-methoxy­styrene), and some polystyrenes bearing ortho -amino groups are capable of taking dominant helical conformations with an excess screw sense at low temperature but lose their optical activities quickly even at ambient temperature. − The helical conformations of vinyl­terphenyl polymers are stable because of high population of rod-like, laterally attached p -terphenyl pendants. − However, they can only be prepared by radical polymerization and are therefore endowed with disordered configurations. In addition, the p -terphenyl-based vinyl monomers demand multistep tedious synthetic procedures.…”

Fabrication of Bioactive Surfaces by Functionalization of Electroactive and Surface-Active Block Copolymers

“…Biofunctional polymers have been prepared with wide variety of applications ranging from diagnostics to therapeutics and tissue engineering [9][10][11][12][13]. An approach to synthesizing polymers with bioactive properties is directly attaching a bioactive moiety to the synthetic polymer.…”