Addition polymers, table

When monomer units add directly to one another, the result is an addition polymer. Table 23.1 lists some of the more familiar synthetic addition polymers. You will notice that each of these is derived from a monomer containing a carbon-carbon double bond. Upon polymerization, the double bond is converted to a single bond ... 

Table 1.1 Reactions by Which Several Important Addition Polymers are Produced ...

Poly(vinyl chloride). PVC is one of the most important and versatile commodity polymers (Table 4). It is inherently flame retardant and chemically resistant and has found numerous and varied appHcations, principally because of its low price and capacity for being modified. Without modification, processibiUty, heat stabiUty, impact strength, and appearance all are poor. Thermal stabilizers, lubricants, plasticizers, impact modifiers, and other additives transform PVC into a very versatile polymer (257,258). 

There are many commercial surface and internal antistatic additives (136). Table 8 Hsts several of the internal antistats along with the polymers for... 

A recent addition to Table 3, Reactive Blue 246 differs from the other dyes and is not added to a finished lens. The dye molecule has methacrylate groups attached to an anthraquinone and is incorporated directiy into the polymer matrix during polymer cure (175). This in-monomer concept has the potential to reduce dramatically the cost of visibiUty tinting of a contact lens. 

The first commercial polymer Table 21.3, II) was offered in 1965 by Union Carbide as Bakelite Polysulfone, now renamed Udel. In 1967 Minnesota Mining and Manufacturing introduced Astrel 360 Table 21.3, V), which they referred to as a polyarylsulfone. In 1972 ICI brought a third material onto the market which they called a polyethersulphone (III) and which they then marketed as Victrex. They also introduced a material intermediate between III and V known as Polyethersulphone 720P (IV) but which has now been withdrawn. In the late 1970s Union Carbide introduced Radel (VI), which has a higher level of toughness. Around 1986 Union Carbide sold their interest in polysulphones to Amoco. In addition the Astrel materials were produced by Carborundum under licence from ICI. 

Thermal Effects in Addition Polymerizations. Table 13.2 shows the heats of reaction (per mole of monomer reacted) and nominal values of the adiabatic temperature rise for complete polymerization. The point made by Table 13.2 is clear even though the calculated values for T dia should not be taken literally for the vinyl addition polymers. All of these pol5Tners have ceiling temperatures where polymerization stops. Some, like polyvinyl chloride, will dramatically decompose, but most will approach equilibrium between monomer and low-molecular-weight polymer. A controlled polymerization yielding high-molecular-weight pol)mier requires substantial removal of heat or operation at low conversions. Both approaches are used industrially. 

The other entries in Table 13.2 show that heat removal is not a problem for most ring-opening and condensation polymerizations. Polycaprolactam (also called Nylon 6) is an addition polymer, but with rather similar bond energies for the monomer and the polymer. The reaction exotherm is small enough that large parts are made by essentially adiabatic reaction in a mold. An equilibrium between monomer and polymer does exist for polycaprolactam, but it occurs at commercially acceptable molecular weights. 

Table II.—Representative Addition Polymers Formed from Unsaturated Monomers... 

Table 3.4 summarises the main characteristics of a variety of sample preparation modes for in-polymer additive analysis. Table 3.5 is a short literature evaluation of various extraction techniques. Majors [91] has recently reviewed the changing role of extraction in preparation of solid samples. Vandenburg and Clifford [4] and others [6,91-95] have reviewed several sample preparation techniques, including polymer dissolution, LSE and SEE, microwave dissolution, ultra-sonication and accelerated solvent extraction. 

Applications The broad industrial analytical applicability of microwave heating was mentioned before (see Section 3.4.4.2). The chemical industry requires extractions of additives (antioxidants, colorants, and slip agents) from plastic resins or vulcanised products. So far there have been relatively few publications on microwave-assisted solvent extraction from polymers (Table 3.5). As may be seen from Tables 3.27 and 3.28, most MAE work has concerned polyolefins. 

Mass spectrometry has a number of features and advantages that can make it a very valuable tool for the identification of organic additives in polymers (Table 6.2). The range of products that can be studied is limited by the ionisation method used and the performance of the mass spectrometer. Mass spectrometry... 

Applications Mass spectrometry has often been used more as an auxiliary, rather than a primary, identification method for additives in polymers. Table 6.5 shows the suitability of various ionisation modes for oligomer (and polymer) analysis. 

Applications Ideally, multiply hyphenated systems should be assembled rapidly in response to real need. Access to these means is restricted to a few laboratories only. Multiple LC hyphenations have been used to analyse test mixtures of polymer additives see Table 7.74. The relative ease with which SEC-UV using CDCI3 as a solvent can be coupled to on-line 1II NMR and an in series off-line FUR (Scheme 7.12b), has been shown for a mixture of polymer additives (BHT, Irganox 1076, DIOP) [666]. Figure 7.35 shows representative spectra for on-flow NMR and MS and off-line FTIR of 2,6-di-f-butyl-4-methoxyphenol. 

The choice of one polymerization method over another is defined by the type of monomer and the desired properties of the polymer. Table 2.1 lists advantages and disadvantages of the different chain growth mechanisms. Table 2.2 summarizes some well known addition polymers and the methods by which they can be polymerized. 

Bulk polymerization of //r/ .v-2-melhyI-1,3-pcntadiene lead only to 1,4-trans addition polymer, however it allows randomization of the trans structure, leading to an atactic polymer. The polymerization of the clathrate of rraw.v-2-mclhyl-1,3-pcntadiene yielded an isotactic 1,4-trans addition polymer. The polymer formed from the bulk had a molecular weight of 20,000 (240 monomer units), and that formed from the clathrate had a molecular weight of 1000 (12 monomer units). Similar results were obtained for other dienes, and the results are summarized in Table 4. It can be concluded that polymerization of dienes in the clathrate lead exclusively to a 1 A-lrans addition polymer, except in the case of 1,3-cyclohexadiene. For this monomer, although the polymer is formed entirely by 1,4-addition, the polymer formed is essentially atactic. In bulk polymerization, the polymerization proceeds in most cases through 1,4-addition (both trans and cis), but in the case of butadiene and 1,3-cyclohexadiene 1,2-additions were also observed. Actually, in the case of the bulk /-induced polymerization of 1,3-cyclohexadiene the 1,2-addition process was favoured over the 1,4-addition process by a ratio of 4 3. 

Most addition polymers are formed from polymerizations exhibiting chain-growth kinetics. This includes the typical polymerizations, via free radical or some ionic mode, of the vast majority of vinyl monomers such as vinyl chloride, ethylene, styrene, propylene, methyl methacrylate, and vinyl acetate. By comparison, most condensation polymers are formed from systems exhibiting stepwise kinetics. Industrially this includes the formation of polyesters and polyamides (nylons). Thus, there exists a large overlap between the terms stepwise kinetics and condensation polymers, and chainwise kinetics and addition (or vinyl) polymers. A comparison of the two types of systems is given in Table 4.1. 

Since many synthetic plastics and elastomers and some fibers are prepared by free radical polymerization, this method is important. Table 6.1 contains a listing of commercially important addition polymers including those that will be emphasized in this chapter because they are prepared using the free radical process. 

There are numerous examples of solid state polymerizations. Here we will briefly describe examples based on addition polymers. Generally, the crystalline monomer is irradiated with electrons or some form of high-energy radiation, such as gamma or x-rays. Since many monomers are solids only below room temperature, it is customary to begin irradiation at lower temperatures with the temperature raised only after initial polymerization occurs. (Some reactions are carried to completion at the lower temperature.) After polymerization, the monomer is removed. Table 6.10 contains a list of some of the common monomers that undergo solid-state irradiation polymerization. 

Anhydrous theophylline (100 mesh) was incorporated into a homogenous 5% w/w solution of the corresponding Eudragit in its solvent (Table 1) containing 2-7% w/w of polyisobutadiene. The phase separation and subsequent deposition of the polymer was effected by desolvating the polymer (Table 1) under stirred conditions. Hardening of the microcapsules was effected by dropwise addition of the chilled non-solvent. After the formation of embryonic microcapsules, they were separated, washed with chilled non-solvent and air dried at ambient temperature. 

The protected amine and primary amine ended polymers show the good molecular weight control and narrow MWD s one expects of anionic polymers. In addition, the hydrolysis of the protecting group does not disrupt polydiene backbones. Such procedures are also gel free. The polymers formed exhibit functionalities approaching the theoretical values, especially for low molecular weight (high amine content) polymers (Table VI), (14, 2). 

An alternative hydrophobic microparticulate dosage form can be produced using poly(alkyl cyanoacrylates) also referred to as simply poly(cyanoacrylates) (PCAs) (Table 11.3). Poly(cyanoacrylates) are a class of addition polymers that undergo polymerization under mild conditions, and even upon the addition of water or ethanol. Poly(cyanoacrylates) have been widely investigated for delivery of biomacromolecules. Due to their properties, cyanoacrylates can easily be formed into two types of particles spheres (Couvreur et al. 1982) or capsules (Al-Khouri Fallouh et al. 1986), both of which can be used to deliver biomacromolecules. The most used of the poly(cyanoacrylates) is poly (isobutyl cyanoacrylate) (PBCA). The reason... 

Table 5. Miscellaneous addition polymers of optically active monomers... 

Table 23. Comparison between the optical activity of some aliphatic addition polymers...

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