Application of the “Strathclyde Route” to Branched Vinyl Polymers in Suspension Polymerization: Architectural, Thermal, and Rheological Characterization of the Derived Branched Products

Abstract

Copolymerizations of methyl methacrylate (MMA) and ethyl acrylate (EA), both monofunctional monomers, with ethylene glycol diacrylate (EGDA) as the brancher (a difunctional monomer) have been carried out via free-radical solvent-free suspension polymerization using 2,2′-azobis(isobutyronitrile) (AIBN) as the source of radicals, in the presence of a chain transfer agent (CTA) to avoid cross-linking and produce only branched polymers. Investigation of various CTAs led to the choice of 1-dodecanethiol (DDT) mainly due to its low volatility and hydrophobicity. Typically, EGDA/DDT mole ratios of ≤0.7 ensure that cross-linking is avoided. The molar mass and the branching architecture of the polymers have been characterized by MALS/SEC and the thermal and rheological behavior by DSC and melt rheology, respectively. The results confirm earlier indications from solution and emulsion polymerizations of the versatility of the “Strathclyde methodology” in producing branched polymers, in this instance in the form of free-flowing spherical particulates and have allowed demonstration of the differences in the thermal and rheological behavior of the branched products relative to their linear analogues.

Synthesis of Branched Methacrylic Copolymers: Comparison between RAFT and ATRP and Effect of Varying the Monomer Concentration

“…Using this hypothesis, the Strathclyde group developed a facile, robust onepot synthetic route for the synthesis of various soluble branched copolymers using conventional free radical polymerization (FRP) chemistry in solution, [4][5][6][7][8][9][10][11][12][13][14][15] emulsion, 16 or suspension. 17,18 In their original paper, a thiol chain transfer agent is used to reduce the mean primary chain length and hence suppress gelation in the branching copolymerization of methyl methacrylate with but-2-ene-1,4-diacrylate. 4 This FRP approach was later extended by both Sherrington's group [5][6][7][8][9][10] and other research groups to *To whom correspondence should be addressed.…”

A simple route to vinyl-functionalized hyperbranched polymers: Self-condensing anionic copolymerization of allyl methacrylate and hydroxyethyl methacrylate

“…This result confirmed the hyperbranched structures of h-PAMA 1 . Moreover, the slope value of 0.48 for h-PAMA 1 was significantly lower than that of l-PAMA 2 (0.61), which also supports the successful synthesis of hyperbranched PAMA [29]. compared to that observed for l-PAMA 2 undoubtedly indicates a densely packed, three-dimensional structure resulting from the hyperbranched topology.…”

Facile one-spot synthesis of highly branched polycaprolactone

“…12,[50][51] In part, this has been attributed to the introduction of branches limiting the ability of the polymer chain to undergo crystallisation. If this is the case then, in this study, the introduction of a branching comonomer into linear PCL should lead to change in the T m , where the observed value would be expected to decrease as DB increases (i.e.…”

“…Hence, in spite of the fact that the synthetic strategies applied deliver poorer control over the molecular structure of these hyperbranched polymers when compared to "true" dendrimers, the economic and practical advantages from adopting these strategies are generally gained without significant negative impact upon the desired beneficial/differentiated material properties. 1,[3][4][5][6][7][8][9][10][11][12] In addition, these more affordable and accessible approaches have led to significant industrial interest targeted towards using these materials in larger scale applications such as imaging agents, reactive resins and industrial coatings. 1,[13][14][15] Compared to linear polymers, highly/hyper branched polymers often exhibit improved solubility, lower (melt) viscosity, higher density of functional-groups and have a more compact/globular structure.…”

“…[3][4][9][10][11][12][31][32][33][34][35][36][37][38][39][40] The 'Strathclyde Method' was a pivotal early example of such a branching synthetic strategy and centred on the standard free radical (SFR) copolymerisation of monofunctional and difunctional vinyl monomers. [9][10][11][12] One of the main conclusions drawn from this work was that gelation, i.e. the formation of an extended crosslinked network, occurred when an average of two or more branch points per chain was achieved.…”