Polystyrene monofunctional

Table I shows the molecular weight and the degree of end group substitution of the monofunctional polystyrene samples obtained. In Table II the corresponding data for the bifunctional samples are given. The samples were characterized by GPC in THF. and were calculated. Comparison with the corresponding nonfunctionalized control samples show good agreement. The results of the light scattering and osmotic pressure experiments with the acid form of the sulfonated polystyrenes were in agreement. No association was observed for THF solutions.

A similar marked tendency to form gels was observed for solutions of telechelic sulfonated polystyrenes in toluene. Again, it was not possible to dissolve the gel by dilution. In principle this could be achieved using a solvent in which the equilibrium of the association of the ionic groups is shifted towards the side of the unimers. Alternatively, the efficiency of the crosslinks can be diminished by addition of monofunctional material. The chains sulfonated only at one end would be incorporated into the micellar... 

Recently this grafting methods has been used to synthesize amphiphilic graft copolymers in which hydrophilic grafts are linked to a hydrophobic backbone. Partly chloromethylated polystyrene is used to deactivate either monofunctional "living" polyethylene oxide or monofunctional "living" polyvinylpyridine. In the latter case subsequent quaternization yields polyelectrolyte grafts. ... 

These results indicate that if polydienes and similar polymers can be prepared quantitatively with tertiary amine terminal groups, then they can be combined with other halogen functional polymers using established techniques to create interesting new block copolymer systems. For example, consider the reaction between telechelic pyridine terminated polybutadiene and monofunctional bromine terminated polystyrene (equation 4) -the latter has been prepared in 95% yield. >it The product would be an ABA... 

In a preliminary study (13) of the reaction betwen monofunctional living polystyrene and AIBN, we have shown that a coupling reaction occurs leading to the incorporation of azo groups either in the middle of the chain or at the end. 

To complete this previous work, it was interesting to study in detail the reaction between AIBN and a living anionic polystyrene, for monofunctional polystyrene I Me as well as for difunctional polystyrene M t Me . 

TABLE 1 Coupling efficiency p as a function of the counter-ion Me and the end group carbanion of the living anionic polystyrene. System monofunctional P > + AIBN... 

Doi et al. 84) have synthesized a new type of diblock copolymer of propylene and styrene by the coupling reaction between the iodine-terminated polypropylene (4) and monofunctional living polystyrene anion (11) in toluene at 50 °C, as represented by Eq. (47). 

Polymeric supports can also be used with advantage to form monofunctional moieties from difunctional (Hies. Leznoff has used this principal in the synthesis of sex attractants on polymer supports (67). Starting from a sheap symmetrical diol he blocked one hydroxyl group by the polymer. Functionalization of cross-linked polymers is mostly performed by chloromethylation (65). A very promising method to introduce functional groups into crosslinked styrene-divinylbenzene copolymers is the direct lithiation with butyllithium in presence of N,N,N, N -tetramethyl-ethylenediamine (TMEDA) (69, 70). Metalation of linear polystyrene with butyl-lithium/TMEDA showed no exchange of benzylic hydrogen and a ratio of attack at m/p-position of 2 1 (71). In the model reaction of cumene with amylsodium, a kinetic control of the reaction path is established. After 3h of treatment with amyl-sodiuni, cumene is metalated 42% in a-, 39% m-, and 19% p-position. After 20h the mixture equilibrates to affort 100% of the thermodynamically more stable a-prod-uct (72). 

PVC can be blended with numerous other polymers to give it better processability and impact resistance. For the manufacture of food contact materials the following polymerizates and/or polymer mixtures from polymers manufactured from the above mentioned starting materials can be used Chlorinated polyolefins blends of styrene and graft copolymers and mixtures of polystyrene with polymerisate blends butadiene-acrylonitrile-copolymer blends (hard rubber) blends of ethylene and propylene, butylene, vinyl ester, and unsaturated aliphatic acids as well as salts and esters plasticizerfrec blends of methacrylic acid esters and acrylic acid esters with monofunctional saturated alcohols (Ci-C18) as well as blends of the esters of methacrylic acid butadiene and styrene as well as polymer blends of acrylic acid butyl ester and vinylpyrrolidone polyurethane manufactured from 1,6-hexamethylene diisocyanate, 1.4-butandiol and aliphatic polyesters from adipic acid and glycols. 

According to the reactants, either diblock or triblock copolymers can be obtained. For instance, PEO-fc-PDMS-b-PEO triblock copolymer and PEO-PDMS diblock copolymers were prepared in high yields by hydrosilylation of a telechelic PDMS which exhibits SiH functions (Mn = 1000) with monofunctional allyl-terminated PEO with Mn = 350 and 500 and telechelic diallyl PEO (Mn = 600), respectively [123]. Their dilute solution properties were investigated. Similarly, interesting PS-b-PDMS thermoplastics have been synthesized from a polystyrene fitted at chain end with a vinyl silane function which reacts with a PDMS bearing SiH end-groups [124]. In addition, hydrosilylation has been used to prepare original copolymers from a,co-disilyl-PDMS 25 and either a,oj-diallyl-polysulfone [125] or a,oj-diallyl poly (L-lactide) (PLLA) as follows [126] ... 

The success of obtaining polystyrene products by free radical processes is affected to a significant extent by the quality and performance of initiators. Monofunctional initiators such as benzoyl peroxide or azobisisobutyronitrile have been utilized in bulk and solution polymerizations for theoretical studies... 

The inverse relationship between rate and MW traditionally presents a problem for the economic production of high MW polystyrene products owing to their slow production rates. The production rate of high MW products is generally increased by the use of peroxides. The addition of a simple monofunctional peroxide such as tert-butyl perbenzoate results in about a 15 % production rate increase over the use of auto-initiation. The use of difunctional peresters [2] and perketals [3] results in >30% rate increases over auto-initiation. However, these... 

In the method proposed by Valeur monofunctional living monodisperse chains are prepared and deactivated by 9-10-bis(bromomethyl)anthracene. The resultant chains contain dimethyl anthracene in their middle, as shown in Fig. 3 (This figure represents labelled polystyrene, but other polymers can be labelled too). Anthracene is a particularly convenient label since it is rigid and rather small, it has a good quantum yield and it is easy to excite. When it is bounded in 1,9 positions, its... 

In the above discussed papers monofunctional polystyrenes with Mn = 2,000 to 4,000 were used. The block copolymers had Mn = 12,000 to 100,000. The molecular weight distribution was quite narrow for directly brominated polystyrenes (Mw/Mn = 1.04) and was slightly broader for xylylene dibromide modified polystyrenes (Mw/Mn = 1.15) (at—10 °C with PF counterion). The molecular weight distribution depended on both temperature and counterion 139). 

Block Copolymer Synthesis by Three-Step Sequential Monomer Addition The preparation of block copolymers by sequential addition of monomers using living anionic polymerization and a monofunctional initiator is the most direct method for preparing well-defined block copolymers. Detailed laboratory procedures for anionic synthesis of block copolymers are available [37, 230], Several important aspects of these syntheses can be illustrated by considering the preparation of an important class of block copolymers (Scheme 7.22), the polystyrene-fe-polydiene-( -polystyrene triblock copolymers. 

Figure 1.9 Plot of concentration of polystyrene chains, Q, vs fraction p of monofunctional chains in networks swollen with benzene p = r mf...

Tan et al. explored the synthesis of monomers that are monofunctional. They have synthesized two hypercrosslinked polymer networks of bishy-dro>ymethyl monomers, e.g., 1,4-benzenedimethanol (BDM), and mono-hydro>ymethyl compounds, e.g., benzyl alcohol (BA) by self-condensation. Precursors of polymers like polystyrene and poly(chloromethylstyrene) ° that are swollen, as well as polyfunctional benzyl chlorides, are synthesized by Friedel-Crafts allq lation in the presence of a Lewis acid. Hydroxymethyl and chloromethyl form a bond with the benzene ring in the presence of an acid catalyst,leading to the design of a new series of hypercrosslinked polymers prepared by directly using the building blocks of hydro)g7methyl aromatics (Figure 3.2). 

K. W. Pepper, Sulphonated cross-linked polystyrene A monofunctional cation-exchange resin,/. Appl, Chem., 1.124, 1951. 

ABC triblock copolymer is formed typically through sequential monomer addition in three ATRP steps. Step One polymerization of styrene (St) by mixing the components together in the following order - CuBr, St, PMDETA, and 1-phenyl ethyl bromide, typically at 100°C. The product is a monofunctional macroinitiator, namely, bromo-terminated polystyrene, P(St)-Br, which is isolated from the reaction products mixture and used in Step Two for the ATRP of tert-butyl acrylate (IBA) at 80°C, the order of addition of the components to the reaction mixture being P(St)-Br, CuBr, tBA, and PMDETA. The product of step 2 is a monofunctional, bromo-terminated macroinitiator, P(St)-l>-P(tBA)-Br, which is isolated from the reaction products mixture and used in Step Three for the synthesis of ABC triblock copolymer by ATRP of methyl acrylate (MA) at 70°C, the order of addition of the components to the reaction mixture being CuBr, P(St)-l>-P(tBA)-Br, MA, and PMDETA. The product of step 3 is the triblock copolymer P(St)-l>-P(tBA)-l>-P(MA)-Br. 

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