Characterization of strictly alternating hydrogenated poly[butadiene‐alt‐(1‐olefin)] copolymers

Abstract

The crystallization behaviour of the series of hydrogenated poly@utadiene-ult-ethene) to poly[butadiene-ult-( 1 -hexadecene)] copolymers was investigated with the aid of differential scanning calorimetry (DSC) and X-ray measurements. Hydrogenated poly(butadiene-ultethene) corresponds to polyethylene and crystallizes in the same way. Hydrogenated copolymers poly@utadiene-ult-propene) through poly [butadiene-ult-( I-decene)] are completely amorphous. In these cases the large branching degree prevents crystallization of the main chains, whereas the side chains are too short to be able to crystallize above the glass transition temperature. The critical length is obviously reached in case of hydrogenated polyputadiene-ult-(1-dodecene)]. The part of the series with large side chains (hydrogenated poly [butadiene-&-( 1 -dodecene)] through poly [butadiene-&-( 1 -hexadecene)]shows the most interesting effects, especially hydrogenated polyputadiene-ult-( 1 -dodecene)], which shows crystallization depending on thermal history. In these substances the side chains are long enough to cause side-chain crystallization, which becomes more pronounced with increasing length of the side chains. The crystal structure is not exactly to be determined, but some data indicate a model, in which the side chains are packed in a manner as in unbranched alkanes, but are also possible orthorhombic. However, the quality of the crystals formed is not very good, so these regions are better described as ordered domains rather than as crystallites.

Facile synthesis of ethylene–propylene fully alternating copolymer and comparison with random copolymer of similar composition

“…It showed a glass transition at −60 °C, which is different from those of iPP and PE (Supporting Information Figure S8). In fact, polymers containing 50–75 mol % ethylene units regularly distributed along the backbone would display amorphous state …”

“…ADMET polymerization of symmetric α,ω‐diolefin monomers followed by exhaustive hydrogenation offers a new viable method to synthesize PE backbone with precisely distributed methyl branches, for instance, PEs containing methyl on every 5, 7, 9, 15, 21, and 39 carbons along the backbone respectively were successfully prepared. Wilke and coworker have successfully synthesized ethylene–propylene copolymer with five methylene between the two methyl branches . They used VO(ONeo) 2 Cl/Al[CH 2 CH(CH 3 ) 2 ] 3 catalyst system to polymerize butadiene and propylene to give poly(butadiene‐ alt ‐propylene), which was then exhaustively hydrogenated to yield (EEP) n copolymer.…”

Melting behavior of polyethylene/α‐olefin copolymers: Narrow composition distribution copolymers and fractions from Ziegler–Natta and single‐site catalyst products

“…With an eye to this practical goal, we close by noting that is possible to create ethylene‐like polymers with short‐chain branches placed regularly along the chain. These products are achieved by strictly alternating copolymerization ( r 1 r 2 = 0)33 or by (nonstatistical) metathesis polycondensation 34…”

Criss‐cross amphiphilic polymers and analogous model systems

“…It is well known that, polymers, such as linear polyethylene, fold in a zig–zag conformation to generate a lamellar morphology with alternating crystalline and amorphous domains; here the domain spacing varies from 5 to 50 nm, depending on the conditions of crystallization. Interestingly, in case of low‐density polyethylene, the presence of randomly distributed branch points act as defects and therefore are excluded from the polyethylene crystals and are forced to occupy the amorphous domains; this in turn disrupts the folding of polymer chains . This idea of defects has been creatively utilized by several research groups to engineer polymer folding in bulk; for instance, Jonas et al .…”