Expandable monomers polymerization

Luck, R.M. and Sadhir, R.K., Shrinkage in conventional monomers during polymerization. In Sadhir, R.K. and Luck, R.M. (Eds.), Expanding Monomers, Synthesis. Characterization and Applications. CRC Press, Boca Raton, FL, 1992, p. 5. 

An interesting modification involves expandable monomers. These materials, synthesized by Dr. William J. Bailey and coworkers at University of Maryland, are spiro monomers, double rings which open and expand on polymerization. They can be useful in adhesives which are based on polymer/monomer solution, such as structural acrylics, radiation-cured acrylates, etc. These monomers can counteract shrinkage on curing, which is detrimental to adhesion. 

In a program to develop monomers that expand on polymerization, we had prepared a series of spiro orthoesters, spiro orthocarbonates, trioxabicyclooctanes, and ketal lactones that could be polymerized with ring-opening by ionic catalysts to give either no change in volume or slight expansion... 

Certain classes of monomers do not shrink and may even expand on polymerization [4], One of the first examples reported was a spiro orthoester that was polymerized to a polymer with an estimated molecular weight of 25,000 using a boron trifluoride etherate initiator [5], In this case, there was no measurable shrinkage on polymerization. The monomer is made by reacting ethylene oxide with a-butyrolactone ... 

The free styrene monomer is restrained within the gel and further reaction with fumarate groups is determined by the spacial arrangement the styrene polymerizes in homopolymer blocks as it intercepts fumarate reaction sites. As individual micelles expand and deplete available fumarate sites in the short polymer chains, the remaining styrene forms homopolymer blocks that terminate at the boundaries between overlapping micelles (Fig. 4). 

Styrene [100-42-5] (phenylethene, viaylben2ene, phenylethylene, styrol, cinnamene), CgH5CH=CH2, is the simplest and by far the most important member of a series of aromatic monomers. Also known commercially as styrene monomer (SM), styrene is produced in large quantities for polymerization. It is a versatile monomer extensively used for the manufacture of plastics, including crystalline polystyrene, mbber-modifted impact polystyrene, expandable polystyrene, acrylonitrile—butadiene—styrene copolymer (ABS), styrene—acrylonitrile resins (SAN), styrene—butadiene latex, styrene—butadiene mbber (qv) (SBR), and unsaturated polyester resins (see Acrylonithile polya rs Styrene plastics). 

One component formulation consists of prepolymers that are intermediate between monomers and the final polymer product. When released from a pressurized container the foaming gas expands and the prepolymer (containing unreacted cyanate groups) reacts with the moisture (water) in air to complete the polymerization reaction and cure. Because curing depends on the presence of moisture, when foam forming reactants are applied to occluded areas, such as cavities,... 

A valid mechanistic model can be very useful, not only in that it can appreciably add to our process understanding, but also in that it can be successfully employed in many aspects of emulsion polymerization reactor technology, ranging from latex reactor simulation to on-line state estimation and control. A general model framework has been presented and then it was shown how it can be applied in a few of these areas. The model, being very flexible and readily expandable, was further extended to cover several monomer and comonomer systems, in an effort to illustrate some of its capabilities. 

If an inert good solvent is used in solution polymerization, the gel thus obtained will have a supercoiled (expanded) structure (Gel B). Gel B swells in good solvents much more than Gel A which is synthesized in bulk. If the amount of the crosslinking divinyl monomer in the reaction mixture is increased while the amount of solvent remains constant, highly crosslinked networks are formed that cannot absorb all solvent molecules present in the reaction mixture and a heterogeneous structure results (Gel C). A part of the solvent separates from the gel phase during polymerization and the formed Gel C consists of two continuous phases, a gel and a solvent phase. If the amount of solvent is further increased, a... 

On the contrary, butadiene and methacryloyl monomers (1,3,4, 10,11) can also be polymerized in the liquid expanded phase. The butadiene lipids have previously been shown to form 1,4-trans-poly(butadiene)s (40j in the monolayer (Eqn. II.). 

The sensor covalently joined a bithiophene unit with a crown ether macrocycle as the monomeric unit for polymerization (Scheme 1). The spatial distribution of oxygen coordination sites around a metal ion causes planarization of the backbone in the bithiophene, eliciting a red-shift upon metal coordination. They expanded upon this bithiophene structure by replacing the crown ether macrocycle with a calixarene-based ion receptor, and worked with both a monomeric model and a polymeric version to compare ion-binding specificity and behavior [13]. The monomer exhibited less specificity for Na+ than the polymer. However, with the gradual addition of Na+, the monomer underwent a steady blue shift in fluorescence emission whereas the polymer appeared to reach a critical concentration where the spectra rapidly transitioned to a shorter wavelength. Scheme 2 illustrates the proposed explanation for blue shift with increasing ion concentration. 

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