Interpenetrating polymer network Flexibility

To prepare an interpenetrating polymer network (IPN) structure, PU networks having ACPA units were immersed with MMA and polymerized. PU-PMMA semi-lPN thus formed was given improved interfacial strength between PU and PMMA phases and showed flexibility with enforced tear strength [65,66]. 

Formation of industrially usable interpenetrating polymer networks derived from caster oil is described in Chapter 27. Products can vary from soft and flexible to hard and tough. 

This is a theoretical study on the entanglement architecture and mechanical properties of an ideal two-component interpenetrating polymer network (IPN) composed of flexible chains (Fig. la). In this system molecular interaction between different polymer species is accomplished by the simultaneous or sequential polymerization of the polymeric precursors [1 ]. Chains which are thermodynamically incompatible are permanently interlocked in a composite network due to the presence of chemical crosslinks. The network structure is thus reinforced by chain entanglements trapped between permanent junctions [2,3]. It is evident that, entanglements between identical chains lie further apart in an IPN than in a one-component network (Fig. lb) and entanglements associating heterogeneous polymers are formed in between homopolymer junctions. In the present study the density of the various interchain associations in the composite network is evaluated as a function of the properties of the pure network components. This information is used to estimate the equilibrium rubber elasticity modulus of the IPN. 

A number of liquid crystalline polyphosphazenes with mesogenic side groups have been prepared (48—50). Polymers with nonlinear optical activity have also been reported (51). Polyphosphazene membranes have been examined for gas, liquid, and metal ion separation, and for filtration (52—54). There is interest in phosphazene—organic copolymers, blends, and interpenetrating polymer networks (IPNs) (55—61) to take advantage of some of the special characteristics of phosphazenes such as flame retardance and low temperature flexibility. A large number of organic polymers with cydophosphazene substituents have been made (62). 

L. Zhao, Z.-L. Zhou, Z. Guo, G. Gibson, J. A. Brug, S. Lam, J. Pei, S. S. Mao, Development of Semi-interpenetrating Polymer Networks and Quantum Dots-Polymer Ncuiocomposites for Low-Cost, Flexible OLED Display Application. J. Mater. Res. 2012,27,639-652. 

The field of interpenetrating polymer networks now takes its place parallel to the fields of polymer blends, grafts, and blocks. Indeed, most of these materials are useful because they imdergo some kind of phase separation. Many IPNs seem to work best when the degree of phase separation is only partial or the size of the domains is in the tens of nanometer range. Those IPNs composed of an elastomer and a plastic to make flexible materials seem to be the most imique among these materials. 

The polymer networks (Figure 9.1(c)) represent promising molecular structmes compared to a coil conformation based on the possible additional immobilization effects which are clearly illustrated if we consider a network given by a copolymeric structure of rigid and flexible segments. Recently, molecular composites by semi-interpenetrating polymer networks have been reported [62]. 

Chuah H H, Kyu T and Helminiak T E (1989) Scaling analysis in the phase separation of poly(j> phenylene benzobisthiazole)/Nylon-66 rigid-rod molecular composites, Polymer 30 1591-1595. Chang K Y, Chang H M and Lee Y D (1994) Molecular composites. 2. Novel block copolymer and semi-interpenetrating polymer network of rigid polyamide and flexible polyamide polyimide, J Polym Sci Part A Polym Chem 32 2629-2639. 

Goujon LJ et al (2011) Flexible sohd polymer electrolytes based on nitrile butadiene rubber/poly (ethylene oxide) interpenetrating polymer networks containing either LiTFSI or EMITFSI. Macromolecules 44(24) 9683-9691, Available at http //pubs.acs.org/doi/abs/10.1021/ ma201662h. Accessed 22 Feb 2013... 

Li H, Wang H, Wang H, Li B. A novel (2,3,5)-connected double interpenetrating three-dimensional network cadmium coordination polymer with flexible tri(triazole) and dicyanamide ligands. Inorg Chem Commun 2011 14(1) 49-51. 

Biopolymer-based interpenetrating networks (IPNs) - Crosslinking of single polymer networks can lead to brittle materials. Biopolymer-based IPNs can result in materials with good strength, less brittleness and increased flexibility, low shrinking, lower sensitivity to solvents and heat, less wearing, and improved... 

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