Block copolymers epoxides

Fig. 20. UV initiated cationic cure of epoxidized block copolymer in the presence of alcohol (Kraton Polymer s EKP-207 and L1203 inono-ol).

An alternate way to make block copolymers involving PDMS blocks 124,125) is to have these chains fitted with epoxide functions at chain end, and to react them with a vinylic or dienic polymer carrying terminal COOH functions. Sequential addition of monomers has also been used, the ring opening polymerization of the cyclic trimer (D3) being initiated by the anionic site of a living polymer126). 

Puskas, J.E., Pattern, W.E., Wetmore, P.M., and Krukonis, A. Multiarm-star polyisobutylene-polystyrene thermoplastic elastomers from a novel multifunctional initiator, Polym. Mater. Set Eng., 82,42 3, 1999. Brister, L.B., Puskas, J.E., and Tzaras, E. Star-branched PIB/poly(p-t-bu-Styrene) block copolymers from a novel epoxide initiator, Polym. Prepr., 40, 141-142, 1999. 

For example, the block copolymers can be modified with a vinyl monomer [281 ]. In addition, diglycidyl ethers [282], that is, precondensates for epoxides, can be used as modifiers. Another possibility is modification with polyamines. 

Block copolymers of /3-PL and /3-BL have been synthesized using (251), although reaction times of several weeks are required.782 Since (TPP)Al-based carboxylates are also known to polymerize epoxides (see Section 9.1.7.2), the sequential addition of /3-BL and propylene oxide (PO) results in formation of a p(/3-BL-/3-PO) diblock.782 However, reversing the order of addition fails to produce the block copolymer since the propagating alkoxide (TPP)Al(OCHMeCH2)nCl does not initiate the ROP of /3-BL. 

The (TPP)A1X family of initiators has been used to initiate the polymerization of a range of other monomer classes including epoxides, episulfides, and methacrylates.776 In the latter case the propagating species is an aluminum enolate and this too may initiate the ROP of lactones, such as 6-VL, albeit slowly. In this way a block copolymer P(6-VL)-b-PM M A of narrow molecular weight distribution (Mw/Mn= 1.11) has been prepared.787... 

Analogous alkoxides, phenoxides, and carboxylates will also initiate the ROP of epoxides, all forming propagating alkoxide species.779 Block copolymers of epoxides with /3-butyrolactone have been prepared via the addition of EO or PO to living poly(ester) chains.782 The oxygen-bound enolate of living PMMA will also react with epoxides to yield diblocks such as PEO-b-PMMA and PPO-b-PMMA (Mn= 12,800, Mw/Mn = 1.16) 787... 

The sequential addition method also allows the synthesis of many different block copolymers in which the two monomers have different functional groups, such as epoxide with lactone, lactide or cyclic anhydride, cyclic ether with 2-methyl-2-oxazoline, imine or episul-Hde, lactone with lactide or cyclic carbonate, cycloalkene with acetylene, and ferrocenophane with cyclosiloxane [Aida et al., 1985 Barakat et al., 2001 Dreyfuss and Dreyfuss, 1989 Farren et al., 1989 Inoue and Aida, 1989 Keul et al., 1988 Kobayashi et al., 1990a,b,c Massey et al., 1998 Yasuda et al., 1984]. 

HMX HMX HMX HMX HMX HMX HMX HMX HMX HMX HMX HMX HNS NTO NTO/HMX NTO/HMX NTO/HMX PETN PETN PETN PETN PETN PETN PETN PETN PETN PETN RDX RDX RDX RDX RDX RDX RDX RDX RDX RDX RDX RDX RDX TATB/HMX Cariflex (thermoplastic elastomer) Hydroxy-terminated polybutadiene (polyurethane) Hydroxy-terminated polyester Kraton (block copolymer of styrene and ethylene-butylene) Nylon (polyamide) Polyester resin-styrene Polyethylene Polyurethane Poly(vinyl) alcohol Poly(vinyl) butyral resin Teflon (polytetrafluoroethylene) Viton (fluoroelastomer) Teflon (polytetrafluoroethylene) Cariflex (block copolymer of butadiene-styrene) Cariflex (block copolymer of butadiene-styrene) Estane (polyester polyurethane copolymer) Hytemp (thermoplastic elastomer) Butyl rubber with acetyl tributylcitrate Epoxy resin-diethylenetriamine Kraton (block copolymer of styrene and ethylene-butylene) Latex with bis-(2-ethylhexyl adipate) Nylon (polyamide) Polyester and styrene copolymer Poly(ethyl acrylate) with dibutyl phthalate Silicone rubber Viton (fluoroelastomer) Teflon (polytetrafluoroethylene) Epoxy ether Exon (polychlorotrifluoroethylene/vinylidine chloride) Hydroxy-terminated polybutadiene (polyurethane) Kel-F (polychlorotrifluoroethylene) Nylon (polyamide) Nylon and aluminium Nitro-fluoroalkyl epoxides Polyacrylate and paraffin Polyamide resin Polyisobutylene/Teflon (polytetrafluoroethylene) Polyester Polystyrene Teflon (polytetrafluoroethylene) Kraton (block copolymer of styrene and ethylene-butylene)... 

Reed 332) has reported that reaction of ethylene oxide with the a,(a-dilithiumpoly-butadiene in predominantly hydrocarbon media (some residual ether from the dilithium initiator preparation was present) produced telechelic polybutadienes with hydroxyl functionalities (determined by infrared spectroscopy) of 2.0 + 0.1 in most cases. A recent report by Morton, et al.146) confirms the efficiency of the ethylene oxide termination reaction for a,ta-dilithiumpolyisoprene functionalities of 1.99, 1.92 and 2.0j were reported (determined by titration using Method B of ASTM method E222-66). It should be noted, however, that term of a, co-dilithium-polymers with ethylene oxide resulted in gel formation which required 1-4 days for completion. In general, epoxides are not polymerized by lithium bases 333,334), presumably because of the unreactivity of the strongly associated lithium alkoxides641 which are formed. With counter ions such as sodium or potassium, reaction of the polymeric anions with ethylene oxide will effect polymerization to form block copolymers (Eq. (80) 334 336>). 

In a reversed way, cationically prepared end-functional polymers are used to quench other living polymers. For example, living anionic polystyrene may be terminated by polyisobutenes with silylchloride terminals [119,120] or epoxide ends [121,122] and by poly(vinyl ethers) with acetal terminals [123], The former case is reported to give H-shaped, tetraarmed block copolymers. 

The hydroxytelechelic polybutadienes also can be reacted with epoxides and maleic anhydride 236,258) with carboxyl-terminated polystyrenes194 , or with a,[Pg.218]

Lanthanide catalysis was again effective in ring-opening reactions of cyclic epoxides (eq 8). Finally, MAO-activated l-RuCL provides block copolymers of ethylene and hex-l-ene. ... 

Most epoxide polymerizations have the characteristics of living polymerizations, that is, the ability to polymerize successive monomer charges forming block copolymers. The expressions for the rate and degree of polymerizations are essentially those used in living chain polymerizations (see Chapter 8). The polymerization rate is given by... 

Table 5.32. Block copolymer formation in PA/PEST blends by carboxylic acid + epoxide coupling agent...

Heterogenization of catalytic nanoparticles stabilized by block copolymers can be carried out by their incorporahon into porous membranes based on poly(acrylic acid) crosslinked with a difunctional epoxide [20-22]. Membranes with defined porosities and amounts of palladium were studied in the selective hydrogenahon of propyne to propene as a model reaction. The porosity of the polymer membrane, the content of catalyst, and the residence time of the reaction mixture were found to influence the conversion and selectivity. The main advantage of these membranes compared to other heterogeneous catalysts is simple adjustment to reaction conditions and fadhtated mass transfer. 

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