Subject bulk polymerization

Four macrolides, 11-undecanolide (12-membered,UDL) [85,86], 12-dodeca-nolide (13-membered,DDL) [86,87], 15-pentadecanolide (16-membered, PDL) [85,86,88,89], and 16-hexadecanolide (17-membered, HDL) [90], were subjected to the lipase-catalyzed polymerization. For the polymerization of DDL, lipases CC, PC, PF, and PPL showed the high catalytic activity and the activity order in the bulk polymerization was as follows lipase PC > lipase PF > lipase CC> PPL. These enzymes were also active for the polymerization of other macrolides. NMR analysis showed that the terminal structure of the polymer was of carboxylic acid at one end and of alcohol at the other terminal. 

When the product of the in situ polymerization of monomeric butadiene to cts-1,4-polybutadiene in the presence of PVC, referred to as Type M PVC, as well as the product of the reaction of cis-1,4-polybutadiene with PVC, referred to as Type P PVC, were subjected to the hydrogen chloride evolution test at 180°C, irrespective of whether the base PVC was prepared by suspension or bulk polymerization, the curve was essentially linear and the time for 0.1 mole % decomposition was generally more than 45 minutes and often as much as 100 minutes (Figures 1 and 2). 

Note ill the bulk polymerization example in Fig. 6-3 that / p increases rapidly at low conversions and then effectively ceases before all the monomer in the system has been consumed. This occurs when the polymerization mixture becomes glassy and even the propagation step becomes subject to diffusion control. Most monomers will solvate and soften their own polymers so that the system does not become rigid until a high proportion of the monomer has been converted. 

The reaction mixture is homogeneous throughout the entire polymerization—i.e., the catalyst, monomer, polymer, and solvent (if used) form a single phase. This is the subject discussed here. Bulk polymerization and solution polymerization are examples of reactions that are usually homogeneous. 

An early published example of reactive processing was a description of bulk polymerization of caprolactam in an extruder to give nylon-6.Intense activity in recent years, mostly in industrial laboratories and at extruder companies, has produced more than 600 patents and 60 published papers on the subject of... 

For the manufacture of a resin that is to be used for soft, water-containing contact lenses with high oxygen permeability, good mechanical strength, and heat resistance, a copolymer of 2-hydroxypropyl isopropyl fiimarate and allyl methacrylate has been the subject of a Japanese patent disclosure [80]. Presumably these polymers were formed by a bulk polymerization process. 

Some information on (he expected course of events in a miniemulsion polymerization of VC may be obtained from results of suspension and bulk polymerization of VC, which has been subject to extensive studies by a number of authors. Ugelstad [93] proposed a simple model for explaining the steady increase in rate with conversion, assuming a thermodynamic equilibrium distribution of radicals below the cntical chain length for precipitation. A very good correlation... 

Acrylonitrile and its comonomers can be polymerized by any of the well-known free radical methods. Bulk polymerization is the most fundamental of these, but its commercial use is limited by its autocatalytic nature. Aqueous dispersion polymerization is the most common commercial method, while solution polymerization is used in cases where the spinning dope can be prepared directly from the polymerization reaction product. Emulsion polymerization is used primarily for modacrylic compositions where a high level of a water-insoluble monomer is used or where the monomer mixture is relatively slow-reacting. The subject of acrylonitrile polymerization was reviewed by Goldfein and Zyubin [31]. Details of these polymerization methods are described below. 

Similarly, cyclobis(hexamethylene carbonate), a dimer of nine-membered cyclic carbonate, was subjected to polymerization in bulk at 140 °C using BuSnCls or Sn(Oct)2 as a catalyst. The best results were obtained with BuSnCls affording polymer yields up to 89% and weight-average molecular weight of Af w = 200 000. In all cases the Af /Af n ratio was of the order of 2. DSC measurements showed that the PC rapidly crystallizes even at a cooling rate of 40 ° C min". ... 

Imbalance in the stoichiometry of polycondensation reactions of AA-BB-type monomers can be overcome by changing to heterofunctional AB-type monomers. Indeed, IIMU has been subjected to bulk polycondensation using lipases as catalyst in the presence of 4 A molecular sieves. At 70 °C, CALB showed 84% monomer conversion and a low molecular weight polymer (Mn 1.1 kDa, PDI 1.9). No significant polymerization was observed with other lipases (except R cepacia lipase, 47% conversion, oligomers only) and in reference reactions with thermally deactivated CALB or in the absence of enzyme. Further optimization of the reaction conditions (60wt% CALB, II0°C, 3 days, 4 A molecular sieves) gave a polymer with Mn of 14.8 kDa (PDI 2.3) in 86% yield after precipitation [42]. 

Methods for making an MIP with appropriate selectivity are the subject of other chapters. Here only the format of the MIP is mentioned. Crushed and sieved bulk MIPs have been widely used for MISPE but uniformly sized and spherical formats (obtained e.g., by precipitation polymerization) are more convenient. The cost of making the MIP is not negligible if the development work is included. However, this is still less than the cost of making a new affinity phase and the MIPs are stable, easily reproduced, and may even be reused, if so wished. 

Tt is well known that the presence of precipitated polymer can influence the course of polymerization. In bulk acrylonitrile polymerization the effects are most dramatic and have been the subject of many studies. The literature on this subject has been reviewed by Bamford et al. (4) by Thomas (29), and by Peebles (23). Under conditions where the system becomes heterogeneous owing to precipitation of small particles of polymer, a protracted acceleration period is observed at the start of polymerization, and the final rate is found to depend on the 0.8 power of the concentration of free radical initiator. Unusual post-polymerization effects are observed in photoinitiated polymerization of acrylonitrile, owing to the presence of trapped radicals which can be detected by electron spin resonance. None of the detailed mechanisms proposed to... 

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