Novel functional polymers: Poly(dimethyl siloxane)–polyamide multiblock copolymers. XI. The effects of sequence regularity on the thermal and mechanical properties

Abstract

Poly(aramid silicone) (PAS) multiblock copolymers were synthesized by the low‐temperature solution polycondensation of isophthaloyl dichloride (IPC) and two diamines, diamino poly(dimethyl siloxane) (PDMS; number‐average molecular weight = 1680) and 3,4′‐diaminodiphenylether (3,4′‐DAPE), in tetrahydrofuran/dimethylacetamide (2/1 v/v). Two synthetic methods for the control of the PAS sequence were used: a one‐step synthesis that presumably gave PAS with a random sequence and the polymerization of 3,4′‐DAPE with a presynthesized dimer, IPC–PDMS–IPC (two‐step synthesis), that presumably gave PAS with an alternating sequence of 3,4′‐DAPE and PDMS segments. In a 1H NMR study of the amide protons of the 3,4′‐DAPE component in PAS, the relative length of the 3,4′‐DAPE segment of randomly sequenced PAS to that of ideally sequenced PAS could be estimated. The glass‐transition temperatures of the 3,4′‐DAPE and PDMS segments of random PAS were 152–234 and −104 to −117 °C, respectively, whereas the alternating PAS sequences showed no glass transition for the 3,4′‐DAPE segments. A tensile test indicated that randomly sequenced PAS behaved like a rubber‐toughened material at lower PDMS contents and like a thermoplastic elastomer at higher PDMS contents, whereas the alternately sequenced PAS behaved like a very soft rubber, showing a high value of elongation at the breaking point. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 841–852, 2003

Amide-containing segmented copolymers

“…The phase-separated bulk morphology resided deeper in the films, which resulted in the observed mechanical properties [131]. Randomly sequenced aramid HS of PDMS-PAr copolymers exhibited high T g values ranging from 150 to semi-crystalline nature of the uniform aramid HS [132]. The dynamic mechanical behavior of PDMS-PAr revealed a relatively temperature-insensitive rubbery plateau with storage moduli that decreased with an increase in the PDMS wt% content(Figure 19).…”

“…Copolymers composed of random HS sequences demonstrated an increase in stress at break with the decrease in copolymer PDMS content with values ranging from 54 to 6MPa for PDMS-PAr copolymers containing 20 to 73 wt% PDMS (1680 g/mol), respectively.Copolymer moduli increased and strain at break decreased with the decrease in copolymer PDMS content. Copolymers that possessed a uniform aramid HS exhibited lower moduli and stress at break than the randomly sequenced HS counterparts, but show a large increase in the strain at break [132]. An aramid homopolymer, composed of 3,4'-diaminodiphenyl ether and isophthaloyl chloride, demonstrated a very high stress at break of ~100 MPa and an elongation similar to a PDMS-PAr containing 55 wt% SS [119].…”

Structural characterization and thermal behaviour of block copolymers of polydimethylsiloxane and polyamide having trichlorogermyl pendant groups

“…Hence as part of our efforts to extend the scope of main group metal chemistry5–8 and the use of aminopropyl‐terminated PDMS, we previously reported the synthesis of aramid–PDMS block copolymers 5, 9. Moreover, quite a few types of organometallic block copolymers such as polyferrocenylsilane‐ b ‐dimethylsiloxane10 and PDMS–polyamide multiblock polymers11 have been synthesized and their properties described. Condensation polymers containing germanium atoms in the main chain each bonded to four carbon atoms have also been reported 12–14.…”

Synthesis, characterization, and water sorption properties of new aromatic polyamides containing benzimidazole and ethylene oxide moieties

“…It is well known that processability may be improved by the addition of flexible chains to the polyamide backbone, which enhance the molecular mobility, providing better solubility and reducing T g 8–11. For this particular purpose, ethylene oxide units have been extensively incorporated into polymers 12–15.…”