Interaction monomer-solvent

The second interaction can be considered as follows, for two monomer units separated by a large number of monomers, the probability of an overlap between the two is non-zero. If the balance of the interactions, monomer-solvent and monomer-monomer leads to a repulsive interaction, as happens in a good solvent, these two distant monomer units repel each other. This excluded volume interaction increases the volume occupied by the macromolecule compared to that of an ideal chain the chain is swollen in a good solvent. A new statistical description of tlie chain conformation is needed, but the key point is that the scaling law still applies and we have R=N, but with v = 0.588 instead of 0.5. The normalised scattering intensity in the asymptotic range becomes ... 

Let us consider a simple self-avoiding walk (SAW) on a lattice. The net interaction of solvent-solvent, chain-solvent and chain-chain is summarized in the excluded volume between the monomers. The empty lattice sites then represent the solvent. In order to fulfill the excluded volume requirement each lattice site can be occupied only once. Since this is the only requirement, each available conformation of an A-step walk has the same probability. If we fix the first step, then each new step is taken with probability q— 1), where q is the coordination number of the lattice ( = 4 for a square lattice, = 6 for a simple cubic lattice, etc.). 

At low concentrations, adsorption is a single-chain phenomenon. The adsorption takes place when the enthalpy gain by the monomer-surface contact with respect to the monomer-solvent contact surpasses the loss of the conformational entropy. In a good solvent the adsorption is not likely unless there is a specific interaction between monomers and the surface. At high concentrations, however, interactions between monomers dominate the free energy of the solution. The adsorption takes place when the enthalpy gain by the mono-... 

The simple initiation process depicted in many standard texts is the exception rather than the rule. The yield of primary radicals produced on thermolysis or photolysis of the initiator is usually not 100%. The conversion of primary radicals to initiating radicals is dependent on many factors and typically is not quantitative. The primary radicals may undergo rearrangement or fragmentation to afford new radical species (secondary radicals) or they may interact with solvent or other species rather than monomer. 

Giupponi and Buzza (2005) explored how the magnitude of the monomer-solvent interactions impacted the dendrimer stmcture using a lattice-based... 

Interactions of monomer units that are far apart in a polymer chain of a gel can be represented as a sum of two- and three-body interactions. Such interactions involve monomer-solvent and solvent-solvent interactions but not hydrophobic interactions. 

The interaction of solvent with monomer is different from that with polymer, i.e. ns,m= ... 

A major difference of branched molecules from chain molecules is that more units are bound together and compressed into a very narrow space around the center of gravity. Hence, an immediate supposition is that in order for the monomer-monomer interaction to balance with the monomer-solvent interaction and the entropy force, and for the excluded volume effects to vanish, more attractive force between monomers are needed than is the case of chain molecules. Now we will focus our attention on concentrated systems such as non-solvent systems. An interesting idea is the influence of solvenf size on the osmotic pressure (screening effect) [19]. 

In an athermal solvent, the monomer-solvent energetic interaction is identical to the monomer-monomer interaction. This makes the net interaction between monomers zero, leaving only the hard core repulsion between monomers. The excluded volume is independent of temperature (v Ks b ), and the chain is a self-avoiding walk of monomers ... 

If the monomer-solvent interaction potential is identical to the monomer-monomer interaction potential, the solvent is called ... 

Three distinct phases may be identified in a radiation-induced polymerization. In the first phase, the interaction of radiation with monomer, solvent molecules or other compounds occurs within a brief interval of 10 to 10 s, resulting in the formation of electronically excited molecules, ions, and electrons. In the second phase, which takes place some to... 

When interactions involving solvent are neglected or cancel each other (bulk polymerization), Eq. (2-12) reduces to its simpler form, involving only monomer-polymer interactions 14) ... 

It has been observed in the cationic polymerization of THF 15 I6) and, to a lesser extent in the polymerization of 1,3-dioxolane 17), that the equilibrium monomer concentration [M]e increases linearly with the initial monomer concentration [M. Moreover, the stronger the monomer-solvent interaction (judged from the heat of mixing) — the more pronounced the dependence of [M]e on [M will be. It can also be assumed, that the reverse dependence would be observed if the solvent-polymer interaction is stronger than that of monomer-solvent. This provides a way of increasing the polymer yield given by ([M]o — [M]e)/[M]o, by the proper, choice of solvent. 

It is rather remarkable that the data obtained by the majority of authors for bulk and solution polymerization are very similar and oscillate within the range from 15 to 23 kJ mol-1 for AHh (and AHM) and from 50 to 90 J mol-1 deg-1 for ASto (and ASss). Within this range some additional dependences can be observed, i.e., for CC14, CH2C12, and CH3N02 solvents both AHM and ASM increase slightly in this order.. Clearly, monomer-solvent and polymer-solvent interactions are responsible for this trend, as indicated in Sect. 2.4. 

For bulk polymerization [M]e can have only one unique value at a given temperature. When solvent is added and the corresponding parameters include the interaction with solvent, [M]e depends on the nature and volume fraction of solvent, thus on [M]o as discussed on p. 6. This effect has been neglected in earlier work which led to serious mistakes in the kinetic treatment of THF polymerization (cf. Part I, and Ref.80)). Leonard has attempted to account for the interactions between monomer, polymer and solvent (Eq. 2-21) in evaluating AHlc and ASlc. These values (No. 14) have already been discussed in Sect. 2.4. 

The data from these two studies of monomer reactivity with DHA, as well as data from a previous study in which M2 was methyl methacrylate (MMA) and DMF the solvent, are summarized in Table V. When possible variations in the Q2 and e.2 values estimated and used for NVP and 4VP are taken into account, and also that some deviation might be caused by the temperature difference, the agreement between the two Qx and ex values for DHA found in this study was satisfactory. However, there was no reasonable correlation between the Qx and ex values for DHA obtained with comonomer MMA. It is possible that some monomer-monomer or monomer-solvent interactions may account for this discrepancy, but we detected no proof of such interactions. 

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