Solid-phase Polymerisation

PET suitable for bottle manufacture is produced by a modified process. Here the high-viscosity polymer melt is subjected to a rapid quenching in water to produce clear amoiphous pellets. These are further polymerised in the solid phase at temperatures just below the T . This is useful to reduce aldehyde content, since aldehyde-forming degradation reactions occur less in the lower temperature solid phase polymerisations. Aldehydes can impart a taste to beverages and it is important to keep the aldehyde content to below 2.5 p.p.m. 

Solid phase polymerisation is used for chain polymerisation processes which are carried out at low temperatures. In such processes the thermal activation is difficult and so for activation of such processes radiation-activation technique is used. These processes are very slow. An example of such a solid phase polymerisation is the preparation of Polyformaldehyde by the radiation polymerisation of solid trioxane. 

Moulded articles can be thermally treated to improve the physical properties, particularly the notched Izod impact strength, but removal of the volatile by-products of the solid-phase polymerisation is a greater problem than for fibres and films 112). Use of internal dielectric heating has been suggested as a means of avoiding limitation of further polymerisation to the surface. 

A method for the depolymerisation of PETP fibres using quarternary ammonium salt phase transfer catalysts in saponification processes at atmospheric pressure and temperatures as low as room temperature is reported. Terephthalic acid was produced in yields as high as 93%. Also reported are similar processes for the depolymerisation of nylon 66 and nylon 46 fibres. Nylon 46 oligomers produced were repolymerised using solid-state polymerisation to produce high molecular weight nylon 46. Nylon 66 was depolymerised to produce oligomers and adipic acid in reasonable yields. 11 refs. USA... 

The polymerisation reaction may be carried out in the solid phase, liquid phase and gas phase. Most of the commercial polymers are prepared in the liquid phase. More recently the solid... 

In coordination polymerisation, the catalyst-monomer complex forms a heterogeneous system in which the metal ion is in the solid phase and the carbanion of the alkyl group is in the solvent phase. The monomer is inserted in between the metal ion and the carbanion and the Polymer chain formed is pushed out from the solid catalyst surface. Because of this coordination polymerisation is also known as insertion polymerisation. 

PolyHIPE has found a successful application in the field of solid phase peptide synthesis (SPPS), where the highly porous microstructure acts as a support material for a polyamide gel [134]. The polystyrene matrix is functionalised to give vinyl groups on its internal surfaces, and is then impregnated with a DMF solution of N, JV -dimethylacrylamide, acryloylsarcosine methyl ester, crosslinker and initiator. Polymerisation grafts the soft gel onto the rigid support, giving a novel composite material (Fig. 16). 

The fabrication of imprinted monolithic solid-phase microextraction fibres has been developed for the selective extraction and preconcentration of diacetylmorphine and its structural analogues, triazines, bisphenol A, anaesthetics, and antibiotics followed by GC or HPLC analysis [156,163,179,196,197]. In addition, the on-line coupling of the imprinted monolith as a preconcentration column with a conventional analytical column has been proposed for the enrichment and cleanup of environmental and food samples [163]. However, at present, the capacity of the imprinted fibres and thus the degree of recovery of analytes are very variable and obviously need some improvement. For example, the recoveries of triazines after SPME with an imprinted monolith prepared by in situ polymerisation of MAA as... 

If we compare the value (—61.7°) for a polymer prepared from 1 (calculated for the molar content of 1), still containing the template, with the value —448.9° for the template monomer 1, it becomes apparent that the molar optical rotation value is considerably decreased as a result of polymerisation. This can have several causes, one being the influence of the polymer matrix. Its effect can be determined by removing the optically active template la. If the boronic acids are then converted with ethylene glycol to the corresponding achiral ester, the polymer shows a positive molar rotation [M] °546 = -1- 110.0°. Apparently, in P-E the imprints generated in the polymer make a positive contribution to the optical rotation value. Measuring the optical rotation in the solid phase allows the... 

The in situ molecular imprinting protocol employing dispersion polymerisation has some advantageous features. The dispersion polymer can be removed from a column and re-packed when a column is damaged after repeated use. Back-pressure of agglomerated polymer particles is less problematic therefore, this in situ method can be applied to a wider range of analytical techniques. Here, two applications of in situ dispersion polymer, solid phase extraction (SPE) and CE are described. 

SAXSAVAXS/RAMAN is especially useful when dealing with chemically induced phase transitions. The example shown in Figure 2(e) is the polymerisation of solvent styrene into polystyrene in which polyethylene is in solution. Polyethylene is soluble in styrene but insoluble in polystyrene. RAMAN allows the determination of the reaction kinetics of polystyrene formation and monitors the crystallisation of the polyethylene. The SAXS monitors the liquid-liquid phase separation followed by the liquid-solid phase transition, whilst the WAXS also observes the liquid solid phase by monitoring the appearance of peaks due to the crystallisation of polyethylene. These are very valuable parameters when trying to define any new manufacturing process. ... 

Polymer nanoparticles with diameters of 50-500 nm are now widely used. As with microspheres and microcapsules, one can differentiate between solid polymeric spheres (nanoparticles) and those spheres with thin polymeric walls (nanocapsules). The locus of polymerisation is not an emulsion droplet as in microencapsulation, hut a micelle. The process involves the soluhilisation of a water-soluhle monomer such as acrylamide along with the dmg or other agent such as antigen to he encapsulated. An organic liquid such as n-hexane serves as the outer phase. Polymerisation is induced hy irradiation (y-rays. X-rays, UV light), exposure to visible light or heating with an initiator. 

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