Entanglement interpenetration

How do highly interpenetrated random coil chains disentangle to cause fracture Disentanglement is considered to occur as shown in Fig. 14, where we depict the response of an entangled chain to a constant (step function) draw ratio X as follows ... 

S. Batten, R. Robson, "Interpenetrating nets ordered, periodic entanglement , Angew. Chem, Int. Ed 1998, 37, 1461-1494. 

Insulation is effectively achieved if one particular set of interactions is very much stronger than the rest. This is the situation that arises in many coordination polymers (S. R. Batten, R. Robson, Interpenetrating nets ordered, periodic entanglement , Angew. Chem Int. Ed. Engl, 1998, 37, 1469-1494 Angew. Chem, 1998, 110, 1558-1595). But coordination polymers are not molecular in all three dimensions, and as such are not within the scope of this essay. 

Most network structures are effective host structures for small guest molecules, often the solvent. Exceptions arise when there is a high degree of interpenetration, i.e. where two or more networks are entangled [7]. This type of host-guest behaviour is not intrinsic to the molecular components themselves, but occurs in cavities or clefts created by the assembly of the network structure. Mol-... 

En vs c [47] is usually associated with the establishment of entanglement couplings [48], Thus, the observed linearity of En vs c dependencies of dendrimer solutions seems to be another manifestation of dendrimer reluctance to interpenetrate, either with other dendrimers or with their parts. 

Interpenetration of the bioadhesive polymer chains and entanglement of polymer and muein ehains, and... 

The diffusion theory states that interpenetration and entanglement of polymer chains are additionally responsible for bioadhesion. The intimate contact of the two substrates is essential for diffusion to occur, that is, the driving force for the interdiffusion is the concentration gradient across the interface. The penetration of polymer chains into the mucus network, and vice versa, is dependent on concentration gradients and diffusion coefficients. It is believed that for an effective adhesion bond the interpenetration of the polymer chain should be in the range of 0.2-0.5 pm. It is possible to estimate the penetration depth (/) by Eq. (5),... 

Figure 2. Loop entanglements that could lead to "locking" under stress (a) locking of free loops b) locking of loops by adsorption on substrates c) locking of loops by Interpenetration into loops on substrate.

This is a theoretical study on the structure and modulus of a composite polymeric network formed by two intermeshing co-continuous networks of different chemistry, which interact on a molecular level. The rigidity of this elastomer is assumed to increase with the number density of chemical crosslinks and trapped entanglements in the system. The latter quantity is estimated from the relative concentration of the individual components and their ability to entangle in the unmixed state. The equilibrium elasticity modulus is then calculated for both the cases of a simultaneous and sequential interpenetrating polymer network. 

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. 

The equivalence between steps, valid in a single component network, does not exist in an interpenetrating polymer network due to the diversity of Interacting species. If ij signifies a step lying on an 1 chain and confined by two entanglements with j polymers, then... 

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