عنوان

Amphiphilic polysiloxane phosphonate monolayers, blends and copolymers

TLpq304456035

انگلیسی

Amphiphilic polysiloxane phosphonate monolayers, blends and copolymers

[Thesis]

E. A. Stesikova

I. Cabasso

State University of New York College of Environmental Science and Forestry

1998

329

Ph.D.

State University of New York College of Environmental Science and Forestry

1998

Phosphonylated polysiloxanes: poly(diethylphosphonobenzyl-usd\alpha\betausd-ethylmethylsiloxane) (PPEMS), copolymers with dimethylsiloxane (poly(PEMS-co-DMS)) and monomer MPECS were studied. Thermal analysis revealed an increase of the Tusd\rm\sb{g}usd with phosphonylation; usd\Delta\rm C\sb{p}T\sb{g}usd characteristic of the copolymers exhibited very low values. However, when Tusd\rm\sb{g}usd is correlated with the number of flexible bonds per monomer unit, the copolymers approached the properties of many conventional macromolecules with the increase of phosphonylation. Monolayer studies revealed that phosphonylated polysiloxanes and their monomers form stable Langmuir-Blodgett (LB) films at the air/water interface. Phase transition is found in usd\piusd-A diagrams; it is composition dependent in the copolymer and temperature-induced in the PPEMS LB films. PPEMS/PDMS blend LB films at the air/water interface exhibited phase separation characteristics corresponding to either two-dimensional monolayer or a bilayer structure. Neither the blends nor the monomer exhibit phase transition. Kinetics and mechanism of silylation reaction of PPEMS and benzyl phosphonate with trimethylsilyl bromide were investigated. A second order relationship with respect to the reactants was found for each individual silylation of diethyl phosphonate, and the substitution of the second ester is accelerated by the first. The silylated product of PPEMS was successfully hydrolyzed to phosphonic acid in mild conditions keeping the siloxane chain intact. Polymer blends of PPEMS and either cellulose acetate (CA) or cellulose acetate butyrate (CAB) were extensively studied. DSC analysis indicated blend miscibility in the full range of compositions. As-cast blend films revealed miscibility. This films show microphase segregation due to recrystallization of cellulose esters upon annealing, as detected by DSC, WAXS and Tusd\rm\sp{H}\sb{1\rho}usd measurements. FTIR revealed interactions involving hydrogen bonding between the phosphoryl groups of PPEMS and hydroxyls of CA. Complexation is found to occur between PPEMS and poly(vinyl phenol), when mixed in dilute dioxane or THF solutions. The complex compositions are close to simple molar ratio, (P = O) /(OH) = 1:1. FTIR and C CP/MAS NMR analysis indicated the existence of strong hydrogen bonds between PPEMS and PVPh. PPEMS/PVPh complex exhibits significantly elevated Tusd\rm\sb{g}usd and Tusd\rm\sp{H}\sb{1\rho}usd. The complex dissociated at a temperature below its Tusd\rm\sb{g}usd and miscible PPEMS/PVPh blend was produced with the Tusd\rm\sb{g}usd and Tusd\rm\sp{H}\sb{1\rho}usd values that are the averages of the parent polymers.

Amphiphilic

Blends

Copolymers

Monolayers

Phosphonate

Pure sciences

E. A. Stesikova

I. Cabasso

p

[Thesis]

276903

a

Y