Solubility and Processability

Correlations of solyent solubility parameters with molar attraction constants and with properties like surface tension, dipole moment, and index of refraction haye been explored.  

It is possible to calculate the solubility parameters for polymers. A relation between the dispersion contribution to the surface energy of polymers (a measurable quantity) and the dispersion solubility parameter of polymers has been found, which is similar to a relation established for low-molecular weight substances (Table 6.4). 

Solvent Dispersion Soiubility Dipole Moment Polar Solubility Refractive Index 

Solvent Dispersion Soiubiiity Dipoie Moment Poiar Soiubiiity Refractive Index 

In the paint and coating industry, organic solvents may be classified by their solubility parameter. The solubility parameter is defined as the square root of the cohesive energy density and is expressed in units of MPa such units are often referred to as a Hildebrand (Ferdinand, R., 1989. Principles of Polymer Systems, 3rd ed., 28-37]. The solubility parameters can be broken into three components representing nonpolar, polar, and hydrogen-bonding contributions (Table 6.5]. 

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Metallic polymers which are stable, soluble and processible, and therefore suitable for industrial applications ... 

Schliiter et al. [161 were the first to describe coupling of aromatic compounds containing aryl-magnesium halide and aryl halide functions, catalyzed by Ni(0) compounds. Here, the authors adapted the principle of attaching solublizing side chains (in the 2- and 5- positions) and arrived at soluble and processable... 

Manna, L., Scher, E.C., and Alivisatos, A.P. (2000) Synthesis of soluble and processable rod-, arrow-, teardrop-, and tetrapod-shaped CdSe nanocrystals. Journal of the American Chemical Society, 122 (51), 12700-12706. 

Chitosan has found many biomedical applications, including tissue engineering approaches. Enzymes such as chitosanase and lysozyme can degrade chitosan. However, chitosan is easily soluble in the presence of acid, and generally insoluble in neutral conditions as well as in most organic solvents due to the existence of amino groups and the high crystallinity. Therefore, many derivatives have been reported to enhance the solubility and processability of this polymer. 

Campo et al. (1999) synthesized the ortho-isomers of PCPP and PCPH, poly[l,3-bis(o-carboxyphenoxy)propane] (Po-CPP) and poly[l,6-bis( o-carboxyphenoxy)hexane] (Po-CPH), in an attempt to improve the solubility and processability of these two polymers. Solubility was improved... 

In this book, we have examined the chemistry behind the possible new approaches to solving the separation problem and have discussed process designs that could be used to implement the Chemistry. In this chapter, we have addressed what we believe to be the biggest problems remaining to be solved for the different approaches described in the rest of the book and have attempted to provide pointers towards possible solutions. These should provide impetus for further research in this important area aimed at improving the chemistry, phase behaviour, differential solubility and process design and eventually lead to the commercialisation of many more homogeneous catalytic processes so as to make chemicals production much more environmentally acceptable. 

Bao, Z. Dodabalapur, A. Lovinger, A. 1996. Soluble and processable regioregular poly (3-hexylthiophene) for thin film field-effect transistor applications with high mobility. Appl. Phys. Lett. 69 4108 1110. 

Chemical modification, through addition of functional groups that disrupt the sp2 pattern or isolation of individual tubes by noncovalent wrapping of various compounds, comes to our aid as one of the simplest and most effective ways to debundle the aggregates, thus improving solubility and processability. 

As previously stated, the rigid polyimides meet many of the requirements for microelectronics applications however, the presence of an ordered morphology, coupled with the lack of a softening transition results in extremely poor self-adhesion. Alternatively, thermally stable thermoplastics exhibit excellent self-adhesion, but often lack sufficiently high temperature dimensional stability and/or solubility and processability from common organic solvents. For instance, po-ly(phenylquinoxaline) (PPQ) has a T in the 370 °C range, thereby overcoming... 

Polysilanes. Following the first reports of soluble and processable polysilanes in the late 1970s, these macromolecules have attracted substantial interest from both fundamental and applied perspectives." The backbone of silicon atoms gives rise to unique electronic and optical properties as a result of the delocalisation of a-electrons. Several polysilanes have also been found to function as useful thermal precursors to silicon carbide fibres and these materials have also attracted attention with respect to microlithographic applications and as polymerisation initiators." ... 

The organic modification of the fullerene, carried out according to many and diverse synthetic strategies, also accomplished the important task of increasing fullerene solubility and processability, since its derivatives are much more soluble than the pristine species in polar solvents or in aqueous media. 

The remaining organic matter is fully saturated with water and therefore of neutral density or becomes water-soluble and processed by biochemical means. What is not degraded is often entrapped within the biomass and removed during the final... 

One of the most common uses for peri-substituted pentacene is as a red emitter in organic light-emitting diodes (OLEDs). Diphenylpentacene, for example, has a fluorescence quantum yield of 30% as a 0.55% dopant in Alq3, yielding OLED devices with efficiencies near the theoretical maximum [34]. Variation of the aryl substituents improves solubility and processing and can increase fluorescence quantum yield (for example, pentacene 25 has a composite fluorescence quantum yield of 32%) [35]. There is one report of the use of diaryl pentacenes in FET devices, but the performance was generally poor (hole mobility for vapor-deposited 23 was of the order of 10-8 cm2 V-1 s-1) [30]. 

PPV derivatives synthesized by the precursor route show very high molecular weight, but have problems of insolubility. Therefore, a nonconjugated polymer with good solubility and processing properties is used as an intermediate or pre-... 

Poly(vinyl alcohol) used to manufacture the poly(vinyl acetal)s is made from poly(vinyl acetate) homopolymer (see Vinyl polymers, vinyl alcohol polymers Vinyl POLYMERS, VINYL ACETATE POLYMERS). Hydrolysis of poly(vinyl acetate) homopolymer produces a polyol with predominantly 1,3-glycol units. The polyol also contains up to 2 wt % 1,2-glycol units that come from head-to-head bonding during the polymerization of vinyl acetate monomer. Poly(vinyl acetate) hydrolysis is seldom complete, and for some applications, not desired. For example, commercial PVF resins may contain up to 13 wt % unhydrolyzed poly(vinyl acetate). Residual vinyl acetate units on the polymer help improve resin solubility and processibility (15). On the other hand, the poly (vinyl alcohol) preferred for commercial PVB resins has less than 3 wt % residual poly (vinyl acetate) units on the polymer chain. 

We tried to optimize the polycoupling conditions by varying such parameters as polymerization time, monomer concentration and monomer addition mode, in an effort to control the polymer formation and to render the polymers soluble and processable. The optimization worked well and our A2 + B3 approach offered ready access to a soluble hb-PAE containing luminescent anthracene and fluorene chromophores (Scheme 5) [27]. Similarly, soluble azo-functionalized polymers hb-P13 and hb-P15 were obtained from the palladium-catalyzed polycoupling of triiodoarenes (12 and 14) with a di-ethynylazobenzene (11) [28]. 

Moldulate/tuning of properties via chemistry Solubility and processibility Large polarizability of constituent molecules Low environmental contamination Potential biocompatibility Photomagnetic effects... 

Generally, two ways have been pursued to overcome these drawbacks. The first is to suppress the strong interchain interactions which cause the poor solubility and processibility [16]. These interchain interactions are drastically reduced when the distance between the polymeric backbones is increased, for instance via the introduction of bulky side-groups. The second possibility is to separate the formation of the first and second chain of the double-stranded polymer, and to process the materials at the stage of the soluble single-stranded intermediates. These precursors can be converted into the (insoluble) ladder polymers during the final step that is a favored thermal process carried out in the solid state. 

Poly(dibenzosilole)s are a relatively new class of compounds for the area of organic electronic materials. Poly(dibenzosilole)s are not easily oxidised and have advantages of solubility and processibility over other polyfluorene analogues, such as carbazoles, dibenzophosphole oxides and dibenzothiophene dioxides. Several groups have already incorporated poly(dibenzosilole)s in the latest organic electronic devices such as OLEDs, OFETs and OSCs and have found improved performance over similar polyfluorene-based devices. With continual advancement in their synthesis, dibenzosilole-based polymers are set to match the popularity of polyfluorenes in organic electronic materials. 

Improvements to the solubility and processability of the polyimides since then have resulted in a plethora of new discoveries and applications . The growth in research and new developments has mirrored the needs of the electronics and aerospace industries for high-performance materials . 

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