Related Experiment Video
Updated: Sep 27, 2026

Synthesis of Terpolymers at Mild Temperatures Using Dynamic Sulfur Bonds in Poly(S-Divinylbenzene)
Published on: May 20, 2019
Influence of Molecular Weight on Conversion and exo-Selectivity in Thermal PIBSA Synthesis from Highly Reactive
Syafiqa Mohd Saleh1, Ahmad Shalabi Md Sauri1, Mohd Fazli Mohammat2
1PETRONAS Research Sdn. Bhd, Lot 3288,3289, Off Jalan Ayer Itam, Kawasan Institusi Bangi, Kajang 43000, Selangor, Malaysia.
Abstract:
Polyisobutylene succinic anhydride (PIBSA) is an important intermediate for ashless dispersant additives used in lubricant formulations, where conversion and exo-selectivity strongly influence product performance. In this work, the thermal synthesis of PIBSA derived from highly reactive polyisobutylene (HR-PIB) 1300 and 2300 was systematically investigated using a full factorial experimental design to evaluate the effects of feed molar ratio, reaction temperature, and stirring rate on conversion and exo-PIBSA yield. Structural confirmation was performed using 1H NMR spectroscopy, gel permeation chromatography (GPC), and saponification value analysis. HR-PIB 1300 achieved conversions of 60-94%, while HR-PIB 2300 achieved conversions of 75-88% under the investigated conditions. A clear molecular-weight-dependent trade-off between conversion and exo-selectivity was observed. For PIBSA 1300, higher temperatures increased conversion but reduced selectivity, resulting in exo-PIBSA yields of 24-56%. In contrast, PIBSA 2300 achieved yields of up to 71%, highlighting the importance of mixing and mass-transfer effects in higher-viscosity systems. These findings demonstrate that optimal thermal maleation conditions are strongly dependent on polymer molecular weight and provide mechanistic insight for future optimization of industrial PIBSA production.
More Related Videos
Related Concept Videos
Molecular Weight of Step-Growth Polymers
As the step-growth polymerization involves step-wise condensation of monomers, the molecular weight also builds up eventually. Consequently, high molecular weight polymers are obtained at the late stages of the polymerization, where 99% of monomers have been consumed.
The extent of the...
Thermal Electrocyclic Reactions: Stereochemistry
Selection Rules: Thermal Activation
Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.
Polymer Classification: Stereospecificity
Free-Radical Chain Reaction and Polymerization of Alkenes
Electrophilic Addition of HX to 1,3-Butadiene: Thermodynamic vs Kinetic Control
π Molecular Orbitals of 1,3-Butadiene
The simplest conjugated diene is 1,3-butadiene: a four-carbon system where each carbon is sp2-hybridized and has an unhybridized p orbital that contains an unpaired electron. According to molecular orbital theory, atomic orbitals combine to form molecular orbitals such that the number...

