Novel polyisobutylene/poly(dimethylsiloxane) bicomponent networks. II. Network structure and property characterization

✍ Scribed by Melissa A. Sherman; Joseph P. Kennedy

• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 251 KB
• Volume: 36
• Category: Article
• ISSN: 0887-624X
• DOI: 10.1002/(sici)1099-0518(199808)36:11<1901::aid-pola25>3.0.co;2-h

✦ Synopsis

The first part of this series concerned the synthesis of novel polyisobutylene (PIB)/poly(dimethylsiloxane) (PDMS) bicomponent networks; the present paper concerns the structure and property characterization of a series of bicomponent networks of varying compositions (PIB wt %/PDMS wt % Å 92/8, 70/30, 50/50, 35/65) having average molecular weights between crosslinks ( M V c ) of Ç 20,000 g/mol. According to network structure analysis by uniaxial equilibrium stress-strain measurements, the experimental M V c 's are in excellent agreement with theoretical values. Hydrosilation end-linking efficiency was quantitated by the amount of sol and functional group analysis by 1 H-NMR spectroscopy. NMR evidence indicates double-bond isomerization during hydrosilation. Network compositions by elemental analysis together with the low sol fractions indicate efficient crosslinking. These data suggest highly efficient network formation and well-defined bicomponent network structures. While PIB and PDMS showed T g 's at 072 and 0124ЊC, respectively, the bicomponent network did not exhibit clearly discernible phase transitions. The heat stability of bicomponent networks increased slightly with increasing PDMS content showing initial (10%) degradation temperatures at Ç 380ЊC in nitrogen and Ç 320ЊC in air. Tensile strengths and elongations were dependent on composition and varied in the 0.6-3.8 MPa and 600-1100% ranges, respectively. The swelling behavior was not much affected by composition.