Effect of block composition on thermal properties and melt viscosity of poly[2-(dimethylamino)ethyl methacrylate], poly(ethylene oxide) and poly(propylene oxide) block co-polymers

Abstract

Block co-polymers can have several properties that are not present in comparable statistical co-polymers, and interest in studying their properties has increased considerably during recent decade [1]. Block co-polymers can have, for example, the ability to form self-organized structures [2]. Especially co-polymers consisting of PDM (poly[2-(dimethylamino)ethyl methacrylate]), PEO (poly(ethylene oxide)), and/or PPO (poly(propylene oxide) blocks have found applications in the field of hydrophobizing paper [3] or other hydrophilic surfaces [4], strengthening agents for wood fibre networks [5,6] and even some biomedical applications [2]. In addition, some special solution properties have been found for copolymers containing cationizable PDM block. E.g. at high pH PEO-b-PDM will aggregate at the temperature where the PDM sequence is totally deprotonated and sufficiently hydrophobic [7]. PDM can also easily be modified into a permanently cationic form by methylation of the tertiary amine group to form a quaternary amine [8,9]. Abstract. To modify the rheological properties of certain commercial polymers, a set of block copolymers were synthesized through oxyanionic polymerization of 2-(dimethylamino)ethyl methacrylate to the chain ends of commercial prepolymers, namely poly(ethylene oxide) (PEO), poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide) (PEO-PPO-PEO), and poly(propylene oxide) (PPO). The formed block copolymers were analysed with size exclusion chromatography and nuclear magnetic resonance spectroscopy in order to confirm block formation. Thermal characterization of the resulting polymers was done with differential scanning calorimetry. Thermal transition points were also confirmed with rotational rheometry, which was primarily used to measure melt strength properties of the resulting block co-polymers. It was observed that the synthesised poly[2-(dimethylamino)ethyl methacrylate]-block (PDM) affected slightly the thermal transition points of crystalline PEO-block but the influence was stronger on amorphous PPO-blocks. Frequency sweeps measured above the melting temperatures for the materials confirmed that the pre-polymers (PEO and PEO-PPO-PEO) behave as Newtonian fluids whereas polymers with a PDM block structure exhibit clear shear thinning behaviour. In addition, the PDM block increased the melt viscosity when compared with that one of the pre-polymer. As a final result, it became obvious that pre-polymers modified with PDM were in entangled form, in the melted state as well in the solidified form.

Effects of architecture on the stability of thermosensitive unimolecular micelles

“…Again, these favorable van der Waals interactions could be one reason for the miscibility of both polymers in the bulk, where hydrogen bonding and electrostatic interactions are negligible (as PPO and PDMAEMA lack charged sites and possible hydrogen bonding sites). 41 Obviously, a higher density of neighboring PPO and PDMAEMA units is required, since the diblock PPO 69 -b-PDMAEMA 100 does not show this behavior at low temperature. Interestingly, the diblock PPO 69 -b-PDMAEMA 100 shows an unexpected behavior at elevated temperatures with a broad, shouldered peak.…”

“…Therefore, close contact of the PDMAEMA units with the PPO units is an immanent feature of the starshaped system leading locally to a situation similar to the situation in bulk mixtures. 41 The close contact triggers the weak, but favorable interactions between PPO and PDMAEMA, leading to a hydrophobic domain at the center of the star. Then, this domain can act as a nucleus for further complexation between PPO and PDMAEMA, as suggested by the IR-data.…”

Melt Rheological Behavior and Morphology of Poly(ethylene oxide)/Natural Rubber-graft-Poly(methyl methacrylate) Blends

“…There are not many rheological studies on blending of PEO with a copolymer containing hard and soft segments [32,33]. Blends of PEO with natural rubber-graft-poly(methyl methacrylate) polymer (NR-g-PMMA) (mole ratio of NR and PMMA-graft polymer: 60%:40%), where the NR backbone is the soft segment and the PMMA-graft polymer is the hard segment, may serve as interesting polymer hosts for SPEs.…”

Tailor-made copolymers for the adsorption to cellulosic surfaces

“…The synthesis of the cationic pentablock copolymer was performed by oxyanionic polymerization from the commercial PEG-b-PPO-b-PEG hydroxyl end capped polymer. [44] QCM-D experiments revealed that the cationic pentablock copolymer exhibited more irreversible binding to the cellulose surface than the triblock copolymer. It was suggested that the most important segment of the polymer for binding to the cellulose surface was the qPDMAEMA blocks.…”