Microphase structure of interpenetrating polymeric networks based on polyurethane and polyurethane ionomer

Abstract

Interpenetrating polymer networks based on polyurethane and polyurethane ionomer were studied using wide‐angle and small‐angle X‐ray diffraction. The polyurethane network is a multiblock polymer based on the trimethylolpropane adduct with 2,4‐toluene‐diisocyanate and poly(propylene oxide tetrahydrofuran) copolymer. Polyurethane ionomer represents a network formed from poly(propylene glycol) containing three OH side groups, 2,4‐toluene‐diisocyanate, 2,2′‐dimethylethanol‐amine, and 1,5‐dibromopentene. The network polymers are characterized by structure heterogeneity developed during microphase separation as a result of hard and soft block segregation. The interpenetrating networks investigated are amorphous systems over the whole range of compositions. They form a very complicated structure where the phase separation of polyurethane and ionomer takes place. It is important to note that phase separation leads to the appearance of microphase structure periodicity due to regular arrangements of microregions enriched by one of the components. The latter fact is considered to be a sign of spinodal phase separation at the initial stages.

Phase-Separated Interpenetrating Polymer Networks

“…Smallangle diffractograms of the initial cross-linked polymers and those of the IPNs of various compositions are presented in Fig. 25 [136,146]. The analysis of these curves indicates the considerable difference between the curves for individual networks and those for IPNs.…”

“…In general, the intensity curves become more diffuse, and their features shift to smaller angles. The diffraction curve of IPN shows two weak maxima (Table 6) [136]. Addition of 10% of PU ionomer to PU is accompanied by a general increase of scattering level over the entire small-angle region, but it does not result in a qualitative change of the scattering curve.…”

“…The angular positions of the interference peaks of both curves are very different. The interplanar distances corresponding to the small-angle peak of the individual networks [136] are correspondingly 7.1 nm for PU and 27.9 nm for PU ionomer. The intensity curves for all individual networks have a common feature-the existence of interference maxima.…”

“…128). At the same time, IPNs based on PU and ionomeric PU (the latter was synthesized from 2,4-TDI, 2,2-dimethylethanolamine, and 1,5-dibromopentane) [146] are characterized by comparatively low segregation degree due to some miscibility. Numerous data discussed in [195] show that the distinctions in viscoelastic behavior of ionomeric IPNs are connected with the formation of complexes between polar and ionogenic groups.…”

Applications of Modulated Temperature Differential Scanning Calorimetry to Polymer Blends and Related Systems

“…Most of the papers describe the synthesis and morphological behaviour [98,[101][102][103][104][105][106][107][108][109], status and developments [110,111], properties [112] and industrial applications [113][114][115][116] and self-organisation [117] of IPNs. In recent years, a significantly increasing number of commercial IPN products ranging from false teeth to ion-exchange resins, high impact plastics, thermoplastics, adhesives, vibration damping materials and high temperature alloys have been developed.…”