Influence of the chain‐end mobility on the melt crystallization of the ethylene oxide (B) sequences in systems containing diblock AB and triblock ABA copolymers with methyl methacrylate (A)

Abstract

Acta Polymerica 38 (1987) Nr. 5 260 DONTH, KRETZSCHMAR e t al. : Influence of the chain-end mobility on the melt crystallization GOWSKI, T. M., KRYSZEWSKI, M., and PVCHERZ, J . : Acta Cryst. C 42 (1986) 172. ,Carl Schorlemmer" Leuna-Merseburg, Sektion Physik, DDR-4200 MerseburgHindering and final blocking of the normal melt crystallization in central ethylene oxide (EO) blocks by methyl methacrylate (MMA) end blocks of increasing lengths in ABA type triblock copolymers synthesized anionicallg in a new way are investigated by differential scanning calorimetry and X-ray scattering. Experimental studies of glass transitions, low temperature nucleation, and the morphologic ten-nanometer structure are included. Low percentage amounts of long homo-PEO chains can crystallize in a n ABA matrix which otherwise is not normally crystallizable. It is concluded from the experiments that in our systems with PEO molecular masses up to 50000 g/mol t h e motion of the chain ends is necessary for melt crystallization under normal conditions. DONTH, KRETZSCHMAR et al.: Influence of thr chain-end mobility on the melt crystallization Actr Polymerica 38 (1987) Nr. 5 261 EinfluP der Kettenendenbeweglichkeit auf die Schmelzkristallisation von Ethylenoxid-(B)-Sequenzen in Systemen, die Diblock AB-und Triblockcopolymere ABA mit Methylmethacrylat (A) enthaltenDie Behinderung und letztliche Blockierung der normalen Schmelzkristallisation von zentralen Ethylenoxid( E 0 ) -Blocken durch Methylmethacrylat-(MMA)-Endblocke ansteigender Lange in Triblockcopolymeren vom Typ ABA, anionisch auf einem neuen Weg synthetisiert, wurden mit Hilfe der differentiellen Scanning-Calorimetrie und der Rontgenstreuung untersucht. Experimentelle Untersuchungen des Glasiihergangs, der Keimbildung bei tiefen Temperaturen und der morphologischen Zehn-Nanometer-Struktur werden eingeschlossen. Geringe Mengen (Prozentbereich) langer Homo-PEO-Ketten konnen in einer ABA-Matrix kristallisieren, welche sonst normal nicht kristallisierbar ist. Aus den Experimenten wird geschlossen, daB in den untersuchten Systemen mit PEO-Molekiilmassen bis zu 50 000 g/mol eine Bewegung der Kettenenden notwendig ist fur die Schmelzkristallisation unter normalen Bedingungen. Bnufinue not3ewnocmu ?conqoe yened na Kpucmumaaqim qened amuneno~cuda ( B ) e cuemeMax ~~~~J Z O U H I A X (AB) u mpu6nounb~x cono.nu&epoe A B A c Memuwfiemalcpmamo~ ( A )npOBeAeH0 H3YYeHMe 3aMeAJleHHR R OKOHYaTeJIbHOrO IIpeKpaWeHHH HOpMaJIbHOfi KpHCTaJIJIH3aqMM TpEI6jIOYHbIX COIIoJIRMepOB 3THJIeHOKCHAa (30) M MeTHJIMeTaKpRJIaTa (MMA) IIpH yBeJIR9HBaIOqHXCH AJIHHaX KOHeYHbIX ~JIOHOB C IIOMOqbIO MeTOAa EI PaCCeHHHFI PeHTreHOBCKHX JIyYefi. 06pa31(ar CHHTe3HpOBaJIHCb IHHOHHbIM c11oco6oM. npOBeneH0 3KCIIepHMeHTaJIbHOe H3y9eHHe IIpOUeCCa CTeKJIOBaHHH, HH3KOTeMIIepaTypHofi HyKJleaVRH Ei MOp@OJIOI'H-YeCKOfi CTPYKTYPbI B 06nac.r~ 10 HM. &IHHHbIe UenEI r o~o -n a o IIpR HH3KOM PIX COAepWaHHH MOryT HpHCTaJIJIEI30-BaTbCH B MaTpHqe ABA, KOTOPaFI 0 6~9~0 He KpHCTaJIJIH3yeTCH. CAeJIaH BbIBOA, 9 T O B HalIIHX o6pasqax, COAepWaWkiX n30...

Synthesis and characterization of poly(ethylene oxide) and poly(perfluorohexylethyl methacrylate) containing triblock copolymers

“…The end block length strongly affects the crystallization behavior of the PEO chains in the block copolymer. As reported by Donth et al [40] no crystallization of PEO chains was observed in triblock copolymers with long poly(methyl methacrylate) (PMMA) end blocks. They investigated end block influence upon the crystallization of central PEO block.…”

Effect of polyhedral oligomeric silsesquioxane nanocage on the crystallization behavior of PEG 5k ‐ b ‐P(MA‐POSS) diblock copolymers achieved via atom transfer radical polymerization

“…This clearly shows a strong influence of the POSS segments on the crystallizability of the PEG chains in the block copolymers. These observations agree with those reported in literature for PEO‐based block copolymers . As an example, Siegwart et al found that in PMMA‐ b ‐PEO‐ b ‐PMMA triblock copolymers, the crystallinity of PEO increases with PEO content.…”

“…These observations agree with those reported in literature for PEO-based block copolymers. [61] As an example, Siegwart et al [62] found that in PMMA-b-PEO-b-PMMA triblock copolymers, the crystallinity of PEO increases with PEO content. Also, a decrease in crystallinity of the PEO has been observed in triblock copolymers, where the central PEO is attached to poly(perfluorohexylethyl methacrylate).…”

Homogeneous crystal nucleation in the poly(ethylene oxide)/poly(methyl methacrylate) system at low temperatures

“…The sharp onset was explained as follows [2, 31. The lower the temperature, the smaller is the size of the critical PEO nucleus (in the order of a few nanometers). Assuming a phase separation at low temperature [2,41 and assuming that the phase decomposition starts also in the few-nanometer-range, then the lower the temperature, the larger and the better purified (after a given annealing time interval) are the regions that are rich with the PEO phase. A size coincidence of the two contrary tendencies is assumed to be the reason for the rather sharp onset temperature TN for nucleation, provided that the crystal nucleation rate is high enough a t such low temperatures.…”

“…A size coincidence of the two contrary tendencies is assumed to be the reason for the rather sharp onset temperature TN for nucleation, provided that the crystal nucleation rate is high enough a t such low temperatures. I n the present paper experimental values of the (relative) number density of crystal nuclei are reported for a triblock copolymer A 4 [2] and a blend A3B in the annealing temperature (T5) interval 235 to 260 K for annealing times (t5) between 1 min and 1 11.…”