Temperature transitions and compatibility in gradient interpenetrating polymer networks

Abstract

Traditional and gradient IPNs of various composition have been prepared from cross‐linked polyurethane and poly(butyl methacrylate). For various layers of gradient IPN cut from the surface to the centre the glass transition temperatures and composition have been determined. The sorption of benzene vapour by various layers was measured, and from these data the free energy of mixing IPN components has been calculated. For all the layer compositions free energies of mixing are positive and dependent on the distance from the sample centre. This effect is thought to be connected not only with composition but with various conditions for phase separation in various layers. Each layer consists of two phases with their own glass transition temperatures. From these data, using the Fox equation, the composition of each phase for various layers have been calculated and the volume ratio of phase evolved was estimated.

Heterogeneity of segmental dynamics aroundtg and nanoscale compositional inhomogeneity in polyurethane/methacrylate interpenetrating networks as estimated by creep rate spectroscopy

“…These networks have earlier been characterized by DRS, over the frequency range from 10 Ϫ2 Hz to 10 9 Hz, 34 and by dilatometry. 35 The broad regions of ␣-and ␤-relaxations were observed (e.g., ␣-relaxation peak extending from 250 K to 360 K at 10 7 Hz). In this study, network glass transition was characterized by DSC over the temperature range from 150 K to 380 K using the Perkin-Elmer DSC-2 apparatus.…”

Equilibrium and Nonequilibrium Microphase Structures of Interpenetrating Polymer Networks

“…From these data it was easy to calculate the ratio of phases in various layers. It was established that changing the ratio of network fractions in an IPN leads to differences both in the composition and ratio of evolved phases in each layer (21).…”

“…This determination has been done for gradient IPNs based on cross-linked polyurethane and cross-linked copolymer of butyl methacrylate and dimethacrylate triethylene glycol (21). Various layers of the IPN sample were cut from the surface to the center of the block; each sample was 0.6 mm thick.…”

Gradient Structure Polymer Obtained from a Homogeneous Mixture: Synthesis and Mechanical Properties

“…[2][3][4][5][6][7][8][9][10][11] Recently, a new method to create gradient materials has been developed. [12,13] Compared to what is usually encountered in the literature, [14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29] the originality of this method relies on the fact that it does not make use of a mixture containing at least one polymer, but it involves a photopolymerization reaction of a homogeneous system, that is to say a system of monomers and oligomers. The principle is based on two steps.…”