Macromers, production

Figure 11. GPC of S11MA MACROMER/BA product 36.2% BA conversion (—) 62.3% BA conversion (--------).

A photoreactive macromer consisting of the reaction product of poly(capro-lactone-co-lactide) and pentaerythritol ethoxylate was prepared by Chudzik et al. (3) and used as tissue implants. 

The authors thank the Automotive Products sector of Du Pont for allowing publication of this work. Dr. N. J. Darmon synthesized the NNA macromers. We thank Dr. N. J. Nahon for his scientific and editorial assistance. Naryann Silva performed all of the mass spectrometric experiments. Audrey Lockton, Christie Connolly, Nary Clavin and Eileen Brennan are acknowledged for their clerical assistance in the preparation of this manuscript. 

The occurence of macrocycles in the product is always interesting from the theoretical point of view. From the practical point of view it is sometimes undesirable, e. g. when macromers should be produced by ring-opening polymerization. In some cases it can be utilized simple methods for preparing crown-ethers in this way have been proposed. 

In a similar way styrene has been reacted with the vinyl group in such macromers leading to products with improved properties such as the contact angle with water and in their surface resistivity (ref. 27). 

Kasuya K-i, Inoue Y, Doi Y (1996) Adsorption kinetics of bacterial PHB depolymerase on the surface of polyhydroxyalkanoate films. Int J Biol Macrom 19 35 0 Kasuya K-i, Ohura T, Masuda K, Doi Y (1999) Substrate and binding specificities of bacterial polyhydroxybutyrate depolymerases. Int J Biol Macromol 24 329-336 Kato M, M. HJB, Kang CK, Fukui T, Doi Y (1996) Production of a novel copolyester of 3-hydroxybutyric acid and medium-chain-length 3-hydroxyalkanoic acids by Pseudomonas sp. 61-3 from sugars Appl Microbiol Biotechnol 45 363-370 Kaushik N, Kumar K, Kumar S, Kaushik N, Roy S (2007) Genetic variability ruid divergence studies in seed traits and oil content of Jatropha (Jatropha curcas L.) accessions. Biomass Bioenerg 31 497-502... 

He, S., Timmer, M. D., Yaszemski, M. J., Yasko, A. W., Engel, P. S. Mikos, A. G. (2001) Synthesis of biodegradable poly(propylene fumarate) networks with poly(propylene fumarate)-diacrylate macromers as crosslinking agents and characterization of their degradation products. Polymer, 42, 1251-1260. 

Titmner MD, Shin H, Horch RA, Ambrose CG, Mikos AG. In vitro cytotoxicity of injectable and biodegradable poly(propylene fumaratej-based networks unreacted macromers, cross-linked networks, and degradation products. Biomacromolecules 2003 4(4) 1026-1033. 

PE mixtures constitute an important part of commercial blends. The information in Appendix, Table 18.12, suggests five major steps in the production of commercial PE, which result in different types of PE, commercially available at present, viz., 1935 - LDPE with LCB 1950 - LLDPE or HOPE catalyzed by, e.g., CraOg, NiO, M02O3, or CoO 1953 - the Ziegler-Natta (Z-N) catalysis for HOPE, UHMWPE, and LLDPE with a broad MWD and heterogeneous comonomer placement 1975 - the metallocene catalysis producing narrow MWD and homogeneously distributed SCB and 1997 - post-metallocene catalysis that leads to PE copolymers with adjustable MW and MWD as well as copolymerization of olefins with polar monomers and macromers. 

Figure 3 shows the effect of reaction temperature on PSep content. It can be seen that 50 C is the best reaction temperature for the formation of epoxy ether terminated macromer. Side reactions occur at temperatures higher than 50 C. When the reaction was carried out at lOO C for 2 hours, a large amount of chlorine ions existed in the water extract of the product, corresponding close to 16 times the amount of the equivalent of PSep. 

Total weight of the product - weight of macromer used... 

Macromer Wt. of EO used g Product g Cyclohexane extract 20% C2HJI extract OH PEO PS... 

Figure 7 indicates that the rate of the individual conversion of the macromer is much slower than that of ethylene oxide, suggesting that in the early stages of copolymerization some amount of ethylene oxide homopolymer is produced and may be found in the product This can be explained by the fact that molecular weight of the macromer is thousands of times larger than that of ethylene oxide and the mobility of the macromer is therefore much smaller than that of ethylene oxide. Also, the steric hindrance is much larger in the macromer than in ethylene oxide. After most of the ethylene oxide is consumed, the phenyl content of the product increases gradually with copolymerization time. Since the macromer does not homopolymerize easily due to... 

Some ideas for more sophisticated chemical modifications may be derived from other procedure described in the literature. For example, PHB can be modified by alcoholysis to prepolymer and then selectively end-capped by maleation [41]. The molecular weight of the macromer can be easily controlled by the alcoholysis time and the molecular weight distribution of the final product with double bonds in the molecule is narrow. The macromer can be used for synthesis of new macromolecules with PHB segments. 

When Cx > 1.0 the rate of polymerisation can sometimes be reduced if the rate of addition of monomer to the radical produced during the transfa- reaction is less than the normal propagation rate. In some cases transfer agents can act as either retarders (when Cx > 1.0) or as inert diluents (when Cx 4 1.0). To be of use in the production of intermediates from which macromers can be synthesised, functionalised transfer agents should possess chain transfer constants within the range 0.1-10, preferably between 0.5-2.0. 

Being biodegradable and biocompatible polymers, FA-based resins are safer for environmental exposures. Another added advantage of using FA in resin synthesis is that macromers of FA are highly unsaturated and therefore can cross-link by themselves or with a cross-linking agent to form polymer networks and provide a novel type of polymer-based products (Shao et al 2013). 

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