Transformation of macromonomers into ring‐opening polymerization macroinitiators: A detailed initiation efficiency study

Abstract

In the present study, n-butyl acrylate macromonomer (BAMM) (M n ¼ 1900 g mol À1 ; PDI ¼ 1.96) has been synthesized via a high-temperature polymerization process. Subsequently, the olefinic termini of the BAMM have been transformed into a diol via a dihydroxylation process using KMnO 4 as an oxidizing agent. The OH-terminated macroinitiator pBA(OH) 2 has subsequently been employed for the ring-opening polymerization (ROP) of e-caprolactone via various catalytic systems, that is, organo-(1,5,7-triazabicyclo[4.4.0]dec-5-ene), metal (tin(II) 2-ethylhexanoate), and enzymatic catalysis (Novozym V R 435). The obtained pBA-b-pCL block copolymers and the initiation efficiency of the BAMM macroinitiator have been investigated via size exclusion chromatography (SEC), electrospray ionization-mass spectrometry (ESI-MS) hyphenated with SEC and liquid chromatography at the critical conditions of both poly(e-caprolactone) (pCL) and pBA. The in vitro enzyme catalysis (eROP) approach proved to be the most efficient catalysis system due to minor transesterification side reactions during the polymerization process. However, side reactions such as transesterifications occur in each catalytic system and-while they cannot be suppressed-they can be minimized. The species generated during the eROP process include the desired block copolymer pBA-b-pCL as main species as well as pCL homopolymer and residual macroinitiator pBA(OH) 2 .

Chromatographic characterization of amphiphilic di‐ and tri‐block copolymers of poly(ethylene oxide) and poly(ε‐caprolactone)

“…The established critical point of PCL in this study has never been reported. The advantage of the current critical conditions is an extended range of PCL molar mass compared to already reported critical conditions of PCL in aqueous mobile phase due to better solubility of higher molar mass PCL and higher pore size of the stationary phase , in line with the findings of Zorn et al . Such separation zone could be valuable for characterization of PCL‐containing block copolymers, polymer blends, and telechelic polymers, with an extended molar mass range.…”

“…1.0% TEA had to be added in the mobile phase to suppress undesired polar interactions (adsorption) of ether groups with free silanol groups of the stationary phase. The chromatographic critical conditions reported in this study possess several advantages compared to the earlier reports . Retention behavior of PCL at different mobile phase composition is demonstrated in Figure .…”

Kinetic Monte Carlo Generation of Complete Electron Spray Ionization Mass Spectra for Acrylate Macromonomer Synthesis

“…The versatility of the high temperature process was investigated by synthesizing an extensive MM library and by conducting postsynthetic steps toward more complex polymer architectures. In addition, improved microstructural control has been explored via controlled radical polymerization (CRP) − also called reversible deactivation radical polymerization (RDRP) in which mediating agent species are present to control the microstructural growth of individual polymer chains. However, even under well-defined CRP conditions, reactions with MCRs led to the aforementioned formation of chain branches and the unavoidable loss of end-group functionality (EGF), especially under high-temperature conditions …”

Macromonomers from AGET Activation of Poly(n-butyl acrylate) Precursors: Radical Transfer Pathways and Midchain Radical Migration

“…30,31 Furthermore, MMs were applied in synthetic approaches to generate more complex materials out of these building blocks. 10,32 For the current study we aimed at applying the principle of MM synthesis from high-temperature acrylate polymerization to a precursor system in order to make identical acrylate MMs with low polydispersity. Therefore, poly(n-butyl acrylate) P(nBuA) polymers were synthesized via conventional ATRP.…”

“…Junkers and Barner-Kowollik refined the method of Chiefari et al and elucidated the reaction mechanism behind MM formation via detailed electrospray ionization mass spectrometry (ESI-MS) studies and kinetic simulations to explore the boundaries and limitations of MM synthesis and acrylate polymerization in general. ,− Indeed, it was shown that acrylate polymerizations at high temperature and conversion resemble (reversible) addition–fragmentation reaction systems, explaining why MMs of such high purity are accessible in the described way. Later, a diverse MM library was made using this approach, and the copolymerization behavior of n -butyl acrylate MMs was investigated. , Furthermore, MMs were applied in synthetic approaches to generate more complex materials out of these building blocks. , …”