Synthesis and Characterization of Maleic Anhydride Grafted Polypropylene with a Well-Defined Molecular Structure

Abstract

Despite the commercial importance of maleic anhydride grafted polypropylene (PP-g-MAH), it has long been a scientific challenge to prepare this polymer with a wellcontrolled molecular structure. This paper discusses a new chemical route that can form PP-g-MAH with desirable MAH content, a single MAH incorporated unit, white color, high molecular weight, and narrow molecular weight and composition distributions. The chemistry involves a unique PP-co-p-BT copolymer as the "reactive intermediate" that can be effectively prepared by metallocene-mediated copolymerization of propylene and p-(3-butenyl)toluene (p-BT), with narrow molecular weight and composition distributions, high molecular weight, and a broad range of p-BT contents. The incorporated p-BT comonomer units provide the reactive sites for the subsequent free radical MAH graft reaction under a suspension condition at a low reaction temperature. The resulting PP-g-MAH polymers were carefully examined by a combination of NMR and GPC measurements, which shows almost no change in polymer molecular weight and distribution and a single MAH incorporation (no oligomerization). The incorporated MAH units increase with the increase of initiator concentration, p-BT content, and reaction time. Evidently, the combination of high reactivity of φ-CH 3 moiety, a favorable mixing condition between the reactive sites and chemical reagents in the swollen amorphous phases, and low reaction temperature results in MAH grafting reaction selectively taking place at the φ-CH 3 moieties without side reactions (i.e., chain degradation and MAH oligomerization). In addition, this suspension reaction process presents an economic method to prepare PP-g-MAH with high polymer content and easy product purification.

Regioselective C−H Xanthylation as a Platform for Polyolefin Functionalization

“…[29] Thiol-ene functionalization worked well in these systems to furnish materials such as glucose-functionalized PEE, whose saccharide group could act to improve the mixing of cellulose/polyolefin blends (6). [30] Finally,sequential addition of butylamine and phenyl glycidyl ether generated hydroxy-containing PEE in aone-pot process (7).…”

Functionalization of Polypropylene by the Combination of Metallocene Catalysts and Reactive Comonomers

“…Based on the same three considerations (i.e., stability, solubility, and versatility) of the “reactive” comonomer, we also investigated p ‐(3‐butenyl)toluene ( p ‐BT) that contains a α‐olefin and three “reactive” benzylic protons (ϕ‐CH 3 ) . The major advantages of p ‐BT comonomer are its easy incorporation and versatility in the functionalization chemistry under various reaction mechanisms, including free radical, cationic, and anionic processes.…”

Simultaneous polypropylene functionalization and nanoclay dispersion in PP/Clay nanocomposites using ultrasound

“…The selection of the monomer to be grafted into the polyolefin, which will generate the compatibilizing agent, should be done considering that it must have unsaturations, polar groups and be stable at the functionalization reaction temperatures. The most used monomers for the PP modification are acrylic acid, MA, Zigler‐Natta catalysts, borane derivatives, esters, and carboxylic acids, although the most reported moiety is the MA. The grafting of MA to polyolefins is usually performed in the extruder, using peroxide as an initiator .…”