Copolymers, segmented mechanical properties

Most of the rheo-optical measurements have so far been performed by IR spectroscopy ° on film samples <50 pm thickness. With the more efficient exploitation of the NIR region, sample thickness and sample preparation have become less of an issue and polymer films up to 1 mm thickness can now be readily investigated by rheo-optical spectroscopy. The potential of FT-NIR spectroscopy can be readily illustrated by rheo-optical investigations of PDMS/polycarbonate (PC) copolymers. The mechanical properties of these segmented block copolymer networks composed of alternating PDMS and PC soft and hard blocks, respectively, such as elasticity, modulus, and stretchability are attributed to the order of the physical... 

In block copolymers [8, 30], long segments of different homopolymers are covalently bonded to each otlier. A large part of syntliesized compounds are di-block copolymers, which consist only of two blocks, one of monomers A and one of monomers B. Tri- and multi-block assemblies of two types of homopolymer segments can be prepared. Systems witli tliree types of blocks are also of interest, since in ternary systems the mechanical properties and tire material functionality may be tuned separately. 

Puskas J.E., Antony P., ElFray M., and Altstadt V. The effect of hard and soft segment composition and molecular architecture on the morphology and mechanical properties of polystyrene-polyisobutylene thermoplastic elastomeric block copolymers, Eur. Polym. J., 39, 2041, 2003. 

Antony, P., Puskas, J.E., Ott, H., Altstadt, V., Kovar, M., and Norton, P.R. Effect of Hard and Soft Segment Composition on the Morphology and Mechanical Properties of Polystyrene-Polyisobutylene Thermoplastic Elastomeric Block Copolymers. Proceedings of the Polymer Processing Society Meeting, May 21-24, Montreal, Canada, 2001. 

The polyether-PDMS soft segments in segmented polyurea-urethanes have been synthesized to combine the good mechanical properties of PUs and the excellent blood-contacting properties of PDMS. The most widely recognized material in this category is Avcothane [Arkles BC, Med Device Diagn Ind 3 30(1981)], which is characterized as a block copolymer of aromatic polyether urethane and PDMS. 

In the polymerization of MM A with 26, the molecular weight of the resulting copolymer increased with the polymerization time (conversion). The St polymerization provided a multiblock copolymer by recombination. It was revealed that the length of the poly(St) segment as well as the mechanical properties of the block copolymer depended on the chain length of the poly(DMS) segments because of phase separation [127]. 

One way of improving the physical and mechanical properties of the polymeric materials produced was to copolymerize the original monomers with stiffer comonomers, whose corresponding homopolymers are endowed with high thermal and mechanical properties. Therefore, 1,4-cyclohexanedimetha-nol was copolymerized with 1,3-propanediol and succinic acid. Segmented copolymers between oligofpropylene succinate)s and PEG were also produced in order to modify their hydrophilic/hydrophobic properties. 

---