Copolymerization monitoring

In the past 20 years, IR monitoring has become increasingly common for polymerization reaction monitoring [53,54-57], therefore, a variety of near and mid-IR in situ probes are now commercially available. While IR is well suited to homopolymerization, copolymerization monitoring, while often quite feasible [58-61], can present... 

Since the ketene will copolymerize with cyclopropanone, excess ketene was removed by addition of 3A molecular sieves followed by evacuation at 1 mm Hg for 2-3 hours at -70°C. The amount of ketene was monitored by FTIR analysis. Ketene has a distinct strong absorption between 2130 and 2150 cm-1 (5,6). The solution FTIR spectrum of cyclopropanone in Figure 1 was taken before ketene removal. 

O. Elizalde, J.M. Asua and J.R. Leiza, Monitoring of high solids content starved-semi-batch emulsion copolymerization reactions by Fourier transform Raman spectroscopy, Appl. Spectrosc., 59, 1270-1279 (2005). 

Beyers et aV° in the Polymer Research Division of BASF-AG used in-line transflectance NIR to monitor methyl methacrylate (MMA) and iV,7V-dimethylacrylamide (DMAAm) monomers in a copolymerization reaction. The work in this paper is of interest as it illustrates an example of calibration development done off-line with a very limited number of prepared calibration samples. The value of the measurement is to control the end properties of the products resulting from the copolymerization reaction. The end properties are related to many parameters including the intramolecular chemical composition distribution (CCD). The... 

C.P. Beyers, H.E.M. Boelens, L. Klumperman and J.A. Westerhuis, In-line reaction monitoring of a methyl methacrylate and A,iV-dimethylacrylamide copolymerization reaction using near-infrared spectroscopy, Appl. Spectrosc., 58(7), 863-869 (2004). 

Analysis of the Copolymerizabilities of Monomers The composition of the copolymers formed was determined by measuring the relative amounts of each monomer, NIPAAM and AAM, that remained in solution after a copolymerization. Copolymerizations were terminated by addition of 1 ml of reaction mix to 9 ml of 0.1% phosphoric acid at 50 C, followed by centrifugation of a 0.4 ml aliquot at 6,500 x g for 5 minutes in an Eppendorf microfuge. After 100 fold dilution of an aliquot of the supernate, 200 pi of this was injected onto an IBM reversed phase Cig HPLC column pre-equilibrated with 2% acetonitrile in 0.1% aqueous phosphoric acid and the eluent monitored at 214 nm. The monomers were eluted using a 0.1% aqueous phosphoric acid (solvent A) acetonitrile (solvent B) gradient as follows for 5 minutes the solvent was 98% solvent A and 2% solvent B, followed by a linear gradient to 80% A and 20% B over 10 minutes. After 5 more minutes at 80% A and 20% B, the solvent was returned to 98% A and 2% B. 

In this paper we would like to describe a new design, based on gas chromatographic analysis of the monomer mixture, for production of constant composition copolymers and its application to emulsion copolymerization. This design was already shortly described and applied to solution copolymerization (3) of methylmethacrylate and vinylidene chloride. Since then, the apparatus was made more simple, more reliable and more accurate. It is actually monitored by an analogic computering system which keeps the ratio of the monomers constant by controlling the addition of one of them. The process based on it can be called corrected batch process because the initial value of this ratio is kept up to the end. 

The increased stability of the graft copolymerized biomaterial has been monitored on the basis of an increase in the number of regeneration cycles. Structurally modified biomaterial (polymerized) could be used up to six times as compared to only four times of unmodified biomaterial, thereby exhibiting the increased environmental stability of the polymerized biosorbent (Table 3.3). 

Compositional control for other than azeotropic compositions can be achieved with both batch and semibatch emulsion processes. Continuous addition of the faster reacting monomer, styrene, can be practiced for batch systems, with the feed rate adjusted by computer through gas chromatographic monitoring during the course of the reaction (54). A calorimetric method to control the monomer feed rate has also been described (8). For semibatch processes, adding the monomers at a rate that is slower than copolymerization can achieve equilibrium. It has been found that constant composition in the emulsion can be achieved after ca 20% of the monomers have been charged (55). 

The consumption of cyclosiloxane during polymerization and copolymerization was monitored by GC. The conversion of D3 was nearly 100 % (Fig. 1). In contrast, the ring-opening polymerization of d/ yielded a conversion of about 60 % only (Fig. 2). During the copolymerization with D3 the cyclic vinylsiloxanes showed a similar behavior as observed during homopolymerization. 

Inagaki and Yasuda [3] investigated transient-stage polymer deposition by using mixed monomers, of which one component is N2. N2 is a non-polymer-forming reactive gas that does not form polymer by itself but copolymerizes with another monomer. In one type of experiment (method A), a steady-state flow of mixed monomer is established and maintained for 5 min without discharge, in which period the adsorption of organic monomer onto the substrate surface (quartz thickness monitor) and other surfaces occurs. 

The experimental techniques followed are descrihed elsewhere (10). Sodium block was added to refluxing toluene under nitrogen and stirred to form small particles of the required size by controlling the stirrer speed. The monomer was added by syringe as rapidly as possible, with cooling if necessary to control the reaction. This step takes less than a minute, except for phenylmethyldichlorosilane, which was too reactive. In the sequential copolymerizations, enough time was left between the addition of the two monomers for >90% of the first monomer to react. The disappearance of the monomers was monitored by gas chromatography. 

SEC-ESIMS provides a tool to monitor the copolymerizations of monomers in the presence of chain-transfer catalysts. Hence, we can... 

The primary disadvantages of metals relate to their cost and quality control. Metals are inherently more expensive to purchase and to fabricate into a useful container. Metals also are prone to the development of pinhole defects during manufacturing that can drastically compromise their barrier properties— especially in particularly thin sections. Not only can these defects be deleterious to the container, but they can also compromise the quality of the pharmaceutical itself. Drug product should be monitored to assure that no metallic packaging defects have been transferred to the preparation—especially in ophthalmic drug products. Much like copolymerization of plastics, metals can be alloyed to enhance their characteristics as The USP has no test requirements for... 

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