Amphiphilic networks. XI. Mechanical properties and morphology

Abstract

ABSTRACT:The bulk properties of two types of amphiphilic networks, poly(2-hydroxyethyl methacrylate)-l-polyisobutylene (PHEMA-l-PIB, H-network) and poly( N,N-dimethylacrylamide)-l-polyisobutylene (PDMAAm-l-PIB, A-network), have been investigated. Tensile strengths decreased considerably by swelling, and the decrease was more severe by swelling in water than in n-heptane. Elongations increased by swelling in water; however, the change was not consistent upon swelling in n-heptane. The hardness of dry networks decreased with increasing PIB content, while for wet networks it was similar to dry networks containing 85 wt % PIB. Small-angle X-ray scattering showed that average interdomain spacings decreased with increasing PIB content. According to dynamic mechanical thermal analysis (DMTA) the glass transition temperatures (T g ) of the respective hydrophobic and hydrophilic components shift toward each other with increasing PIB content. A ''liquid-liquid transition'' ( T ll ) above the T g of the hydrophilic component was apparent by DMTA, but could not be found by differential scanning calorimetry (DSC).

Organic hybrid of chlorinated polyethylene and hindered phenol. I. Dynamic mechanical properties

“…In many biphasic systems, 13,24 it has been identified that the magnitudes and the location of a glass transition caused by a single phase are dominated by its content. On the other hand, the compatibility of AO-80 and CPE is considerably enhanced with increasing thermal forming temperature.…”

Microphase separation under constraints: a molecular thermodynamic theory for polyelectrolytic amphiphilic model networks in water

“…(5) in Section 3 as the product of the surface tension between water and the hydrophobic units, g, times the hydrophobic interfacial area S cylinder interfacial : Again, g is provided by Eq. (6).…”

“…This structure leads to swelling in both aqueous and organic media [2], and adsorption of both hydrophilic and hydrophobic solutes [3,4]. Moreover, there is a growing body of evidence for the microphase separation of CSACPNs both in water and in organic solvents, but particularly in water [5,6]. The main application of these materials is drug delivery, with the use of CSACPNs both as drug release matrices [3,4] and as semi-permeable membranes [7].…”

From thermoplastic elastomers to designed biomaterials

“…20,21 Transmission electron microscopy of a typical amphiphilic network has shown 20-50-Å -diameter bicontinuous domains with a salt-and-pepper morphology.…”