Synthesis MACROMER

A polyaddition reaction has also been employed in the MACROMER synthesis... 

In this review, the term macromer is used to describe oligomer or polymer precursors that undergo reversible association to form supramolecular polymers or networks. Macromer synthesis, although a crucial aspect of supramolecular science, is also out of the scope of this review. Several comprehensive reviews of the synthesis of H-bonding polymers are available [10, 11,42] and primarily describe the application of controlled radical polymerization techniques, including atom-transfer radical polymerization (ATRP), reversible addition-fragmentation chain transfer (RAFT) polymerization, and nitroxide-mediated polymerization (NMP). For synthesis of telechelic polymers, avoiding monofunctional impurities that can act as chain stoppers is crucially important [43],... 

Macromers are then short polymers, which contain an active end group. This end group can be a site of unsaturation, heterocycle, or other group that can further react. Macromers are usually designed as intermediates in the complete synthesis of a polymeric material. These macromers can be introduced as side chains (grafts) or they may serve as the backbones (comonomer) of polymers. The macromers can also act as separate phases. 

There are some problems associated with the synthesis of MACROMERS when the styryl anion is reacted with certain functional monomers such as ... 

Research Focus Synthesis of dithiocarbonate and thioether macromers and polymers to deliver reactants to a body cavity in a fluid form. 

This envelope is vinyl terminated MMA macromer (VII), the vinyl group is necessary for the synthesis of larger polymers. We also observe a small distribution ( 3Z) following the formula ... 

The synthesis of novel initiators and the ROP of existing or new monomers and macromers substituted with functional groups provide a very interesting and promising strategy for producing structurally advanced macromolecules. 

The cyclic tin alkoxides have the additional advantage of offering a convenient synthetic pathway for the synthesis of macromers, triblock, and multiblock copolymers [81,82]. Macromers from l-LA [83],e-CL [84], and l,5-dioxepan-2-one (DXO) [85] have been synthesized as well as triblock poly(L-LA-b-DXO-b-L-LA) [86] and multiblock copoly(ether-ester) from poly(THF) and e-CL [87]. The polymerization proceeds by ring expansion and the cyclic structure is preserved until the polymerization is quenched by precipitation. 

Materials. All monomers used for synthesis were free of inhibitors and freshly distilled 2-hydroxyethyl methacrylate (HEMA) dimethyl-acrylamide (DMA) N-vinylpyrrolidone (NPV) methylmethacrylate (MMA) 2-ethylhexylacrylate (EHA) isopropylmethacrylate (IPMA) n-butyl-acrylate (BA) ethyleneglycol-dimethacrylate (EGDMA) dimethacrylate macromer obtained by reaction of 1 mol polytetramethylene oxide diol (MW 2000) with 2 mol 2,4,4-trimethyl-l,6-diisocyanatohexane and 2 mol HEMA (PX). ... 

Kennedy 441 reported the synthesis of a MACROMER on the basis of the cationic polymerization of isobutylene. 

Macromers by Controlled Initiation. New and unique graft copolymers can be prepared by copolymerizing macromers (macromolec-ular monomers) with conventional monomers. The synthesis of poly(butyl acrylate- -isobutylene), i.e., the first graft synthesis that involves carbocationic controlled initiation, has recently been accomplished by the following route (9) ... 

Hult and co-workers performed a very tedious study on the synthesis of end-functionalized PCL macromers using Novozym 435 as catalyst [83]. Enzyme-catalyzed ROP of e-CL was performed with addition of potential chain initiators [e.g., 9-decenol, 2-(3-hydroxyphenyl)-ethanol, 2-(4-hydroxyphenyl)ethanol, and cinnamyl alcohol] to the reactions. Alternatively, acids and esters containing... 

Scheme 9.1 General schematic of the synthesis of PMMA-g-PDMS copolymers using the Macromer technique (DeSimone et al., 1990).

The concentration of these kinds of macromers, used in polymer polyol synthesis, is around 2-5% compared to the final polymer polyol. Higher concentrations lead to an undesired, substantial viscosity increase together with a decrease in median diameter of the resulting solid polymer particles. A lower concentration of macromer leads to poor stabilisation of the resulting polymer dispersion. 

The presence of macromers in the synthesis of polymer polyols has another important technological advantage it avoids the formation of crusts of vinylic polymer on the walls of the reactor used for radical copolymerisation. 

A simple and convenient method to obtain macromers useful for polymer polyols synthesis is based on the following succession of reactions (a-c) [52] ... 

Generally, the nonreactive NAD is used in higher concentrations, than the macromers in graft polyether polyols synthesis, of around 10-15% compared to the final polymer polyol. 

One of the most common technologies for the synthesis of polymer polyols by a radical mechanism is based on the stepwise addition of a mixture of vinylic monomers (polyether polyol, initiator, transfer agent (mixture I)) to a second mixture (mixture II) of polyether polyol (identical with the polyether used for mixture I) and NAD (macromer or nonreactive NAD) under a nitrogen protective atmosphere, in the polymerisation reactor at 115-... 

An alternate route to graft copolymers is by synthesis of macromolecules possessing exactly one polymerizable group in the chain and their subsequent polymerization, i.e. grafting through. Such reactive polymers are macromolecular monomers, i.e. Macromers as abbreviated by Milkovitch 159), who was the first to call the attention of the scientific community to the importance of this field although macromonomers have been prepared and copolymerized as early as 1962 160). 

---