Synthesis and basic characteristics of polypropene-block-poly(ethene-co-propene) by modified stopped-flow polymerization with an MgCl2-supported Ziegler catalyst

Abstract

SUMMARY: A well-defined diblock copolymer, polypropene-block-poly(ethene-co-propene), was synthesized by modified stopped-flow polymerization with an MgCl 2 -supported Ziegler catalyst. The copolymer shows a unimodal gel permeation chromatography (GPC) elution curve without any material in the low molecular weight region. The molecular weight can be controlled by the polymerization time (ca. 0.1 to 0.2 s). Furthermore, the elution pattern by cross fractionation chromatography showed that the block copolymer eluted at each temperature region between 0 8C to 120 8C is composed of a uniform material. After extraction with heptane, the 13 C NMR spectra showed that the signals from poly(ethene-co-propene) remain unchanged in the block copolymer but are absent in a corresponding polypropene/poly(ethene-co-propene) blend. The results of differential scanning calorimetry (DSC) and optical microscopic observation indicate not only the formation of a block copolymer with a chemical linkage between the polypropene block and the poly(etheneco-propene) block, but also the regulation of the crystalline morphology in the block copolymer by changing the composition.

Evaluation of the Initial Stages of Gas‐Phase Ethylene Polymerizations with a SiO2‐Supported Ziegler–Natta Catalyst

“…More recently, studies have begun to focus on the development of the morphology of the polymer particles obtained with heterogeneous Ziegler-Natta catalyst systems at very short times of polymerization [16][17][18] and under industrial conditions. [19][20][21] In particular, the studies of Di Martino et al [22][23][24] provided a detailed investigation of the kinetics, morphology and polymer properties; these were conducted in slurry polymerizations of ethylene on a MgCl 2 -supported Ziegler-Natta catalyst at very short times (t !…”

Novel Olefin Block Copolymer, Polypropene-block-poly(methylene-1,3-cyclopentane-co-propene), Synthesized from Propene and 1,5-Hexadiene by a Modified Stopped-Flow Method

“…In particular, tailor-made olefin block copolymers having crystalline and amorphous components are eagerly required, because the characteristic properties of the block copolymers can be applied to a broad spectrum of areas including compatibilizers and composite materials. In a previous study, [3] we first demonstrated the synthesis of a brand new block copolymer, polypropeneblock-poly(ethene-co-propene) (PP-b-(PE-co-PP)), using a modified stopped-flow polymerization method in the presence of a MgCl 2 -supported Ziegler catalyst.…”

Uma revisão sobre polimerização de olefinas usando catalisadores Ziegler-Natta heterogêneos

“…O método Stopped-Flow ¶ (SFM) [92] , comumente usado em estudos de cinética homogênea e para análises de polimerizações em solução e em suspensão [93][94][95] , também é extensamente empregado para estudo do desenvolvimento morfológico de partículas poliméricas em polimerizações conduzidas com catalisadores heterogêneos em experimentos realizados com tempos de polimerização extremamente curtos em condições industriais de operação [96][97][98][99][100][101][102][103][104] . Seguindo o conceito similar ao SFM, Machado et al [105] desenvolveram um novo aparato experimental (denominado de Short Stop Reactor ** -SSR) especialmente para o estudo da polimerização nascente e a fragmentação de catalisadores heterogêneos em polimerizações de olefinas conduzidas em fase gasosa.…”