Thermal polymerization repeat unit

The impetus for the preparation of polymeric metal phthalocyanines is repeatedly traced to an early report on the thermal stability of copper phthalocyanine 24). Dent and Linstead 24) described it to be exceptionally resistant to heat and at about 580°C it may be sublimed at low pressure in an atmosphere of nitrogen or carbon dioxide. This description served to suggest to several groups that incorporation of a metal phthalocyanine structure into a polymeric repeat unit would yield polymers of exceptional thermal stability. 

The reaction of ACPC with linear aliphatic amines has been investigated in a number of Ueda s papers [17,35,36]. Thus, ACPC was used for a interfacia] polycondensation with hexamethylene diamine at room temperature [17] yielding poly(amide)s. The polymeric material formed carried one azo group per repeating unit and exhibited a high thermal reactivity. By addition of styrene and methyl methacrylate to the MAI and heating, the respective block copolymers were formed. 

The polymeric peroxides, ( OOCH-CXH ) , where X = H, GTL, (T1 (T l> etc., are viscous liquids or amorphous solids having as many as 10 repeating units. These compounds usually explode when heated. The products obtained from the thermal or photodecomposition show that cleavage of both oxygen-oxygen and carbon-carbon bonds occurs. 

There is no direct evidence that in TS-6 individual chains formed in the autocatalytic reaction regime are only a few hundred repeat units long, contrary to what is to be expected from the 200-fold increase of the reaction rate. However, there is a recent estimate based on polarization currents measured during thermal polymerization. Following earlier work on the pyroelectric response of TS Bertault et al. attributed the electric signal to an alignment of non-compensated dipolar defects associated with the chain ends. From the average value of the polarization they concluded that one chain can at most comprise a couple of hundred monomer units. 

It was found that soUd-state polymerization of these monomers always proceeds by 1,4-addition. Furthermore, polydiacetylene 96 could be thermally reacted and the structure of the final polymer was proposed to be that of the ladder polymer 97 where the repeating unit is l,6-didehydro[10]annulene (98), i.e. two conjugated polydiacetylenes. However, the annulene 98 is expected to be unstable. In fact, its cycloaromatization reaction to the... 

There has been a significant effort to copolymerize TMC with lactones and other carbonate monomers. Matsumura et al. performed copolymerizations of lactide with TMC using porcine pancreatic lipase at 100°C for 168h [113]. They obtained random copolymers with Mw values up to 21000. However, since trimethylene carbonate is known to thermally polymerize at 100 °C (see above), the extent of polymerization that occurs due to activation of monomers at the lipase catalytic triad versus by thermal or other chemical processes is not known [95], Lipase AK-catalyzed copolymerizations of l,3-dioxan-2-one (TMC) with 5-methyl-5-benzyloxycarbonyl-l,3-dioxan-2-one (MBC) were carried out in bulk at 80 °C for 72 h (Scheme 4.27). Although TMC reacted more rapidly than MBC, the product isolated at 72 h appeared to have a random repeat unit distribution [102], Similarly, using Novozym 435 in toluene at 70°C, TMC/PDL copolymerizations were performed and gave random copolymers. 

The molecular structure of these copolyesters is complex and is affected significantly by the synthesis conditions, thermal history, and processing conditions. The sequence distribution of the different repeating units is often found to be more or less in blocks, as indicated by cross polarization solid state C-NMR and X-ray diffraction [9]. The as-polymerized polyester is highly crystalline, indicating block-like ordered sequences, but becomes less crystalline after processing from the molten state, which is due to further transesterification reactions and the formation of a more random sequence distribution. 

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