Siloxane block copolymers

Block copolymers with known block lengths were prepared by Bostick (1970) using organocyclosiloxanes with lithium-based catalysts. For example, when hexamethylcyclotrisiloxane is reacted with the lithium salt of diphenyl-siloxane diol, a multistep addition polymerization occurs  

Further, when another cyclosiloxane is added to this reaction system, polymerization resumes to produce block poly(organosiloxanes) of the ABBA type. Because the B sections are identical, we may treat the product as a triblock copolymer. For example, when hexaphenylcyclotrisiloxane is added to the product of reaction (6.25), the reaction may be represented as follows  

Typical compositions of the materials prepared are shown in Table 6.3 for triblock copolymers (Fritzsche and Price, 1970). 

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Siloxane block copolymers, 451 Siloxanes, 450-456 Silyl ether displacement, poly(arylene ether sulfone) synthesis via, 340... 

Pioneering work in living anionic copolymerization of siloxanes was reported by Morton and co-workers 139 140, who synthesized isoprene-dimethylsiloxane block copolymers utilizing D4 as the siloxane monomer. The use of D3 in the synthesis of siloxane block copolymers with controlled structures was demonstrated by Bostick and others. Excellent reviews of these earlier studies and subsequent developments are available in the literature 22 137 13S). 

Somewhat limited work has been reported over the last decade. There are several reports on the synthesis and physical and structural characterization of styrene-dimethylsiloxane 141 144) and methylmethacrylate-dimethylsiloxane145> diblock, triblock and multiblock copolymers. Several reports are also available on the thermal223), solution 224,2251 and surface196 2261 characterization of various styrene-dimethyl-siloxane block copolymers synthesized by anionic techniques. 

Preparation and characteristics of ABA type polycaprolactone-b-polydimethyl-siloxane block copolymers have been recently reported 289). In this study, ring-opening polymerization of e-caprolactone was achieved in melt, using a hydroxybutyl terminated PSX as the initiator and a catalytic amount of stannous octoate. Reactions were completed in two steps as shown in Reaction Scheme XIX. 

Initiation of stannous octoate-catalyzed copolymerization of e-caprolactone with glycerol was used to prepare a series of trifunctional hydroxy-end blocked oligomers, which were then treated with hexane-1,6-diisocyanate to form elastomeric polyesterurethanes with different crosslink densities (49). Initiation of e-caprolactone polymerization with a hydroxypropyl-terminated polydimethylsiloxane in the presence of dibutyl tin dilaurate has been used to prepare a polyester-siloxane block copolymer (Fig. 4) (50). 

The initiation of the cyclic siloxane monomers with a living polymeric lithium species such as polystyryl lithium leads to block copolymers, as outlined in Scheme 2, were also of interest. These styrenic-siloxane block copolymers were prepared with siloxane contents from 10 to 50 weight percent. 

Styrenic-siloxane block and graft copolymers, Tg dependence on architecture and molecular weight, 95,95/ Styrenic-siloxane block copolymers, 86 Substrate catalyst ratio, chloromethylation, 18 Sulfonation, instability of sulfonated PPO, improvement, 6 Surface grafting... 

Figure 1. Stress-strain curves of polycarbonate-polydimethyl-siloxane block copolymers (Crosshead Speeds 5 cm/min). (Reproduced from Refs. 15 18. Copyright 1980, 1984 American Chemical Society.)...

Lithographic Evaluation of Phenolic Resin—Dimethyl Siloxane Block Copolymers... 

OXYGEN REACTIVE ION ETCHING (RIE) OF NOVOLAC-SILOXANE BLOCK COPOLYMERS... 

Thus, N-pyrimidine phthalimide reacted with hexylamine at room temperature to form an amide-amide. The initial amide-amide formation proceeded more rapidly in chloroform as compared to dimethylsulfoxide (DM SO). However, the ring closure reaction to the imide was favored by the more polar, aprotic DMSO solvent, yielding the imide in nearly quantitative yield after 3 hours at 75 °C. The authors were able to utilize this synthetic approach to prepare well-defined segmented poly(imide-siloxane) block copolymers. It appears that transimidi-zation reactions are a viable approach to preparing polyimides, given that the final polyimide has a Tg sufficiently low to allow extended excursions above the Tg to facilitate reaction without thermal decomposition. Additionally, soluble polyimides can be readily prepared by this approach. Ultimately, high Tg, insoluble polyimides are still only accessable via traditional soluble precursor routes. 

L.M. Robeson, A. Noshay, M. Matzner and C.N. Merian, Physical Property Characteristics of Polysulfone/poly(dimethyl siloxane) Block Copolymers, Angew. Makro-mol. Chem. 29, 47 (1973). 

Figure 11.27 29Si-NMR spectrum of a silphenylene-siloxane block copolymer (67 mol % DMS), observed at 59.6 MHz [29]...

JP 05311144 (Japanese) 1993 Heat-resistant adhesive compositions containing polyimide-siloxane block copolymers Ube Industries, Japan H Inoe, S Takabayashi, T Funakoshi, K Sonoyana Useful for Cu-clad laminates of printed circuit boards and tape-automated bonding with good flexibility and heat resistance Formulated compositions containing siloxane-imide block copolymers made from aromatic tetracarboxylic acids and aromatic diamines and aminosiloxanes... 

US 5,028,681 (American) 1991 Novel poly(imide siloxane) block copolymers and process for their preparation General Electric EN Peters Injection moldable block copolymers with high IV and excellent chemical/physical properties. Blends useful for impact modification Novel siloxane-imide block copolymers and a process for their preparation are covered. The method involves reacting a hydroxy-terminated polyimide oligomer with a siloxane oligomer with dimethylamino, acetyl or chlorine end-groups... 

Inoue H Takabayash S Muramatsu T, Funagoshi T, Hirano T. Polyimide-siloxane block copolymer-based heat-resistant adhesive compositions. US Patent 5180627 A 930119 11 pp... 

Raez J, Manners I et al (2002) Nanotubes from the self-assembly of asymmetric crystalline — coil poly(ferrocenylsilane — siloxane) block copolymers. J Am Chem Soc 124 10381-10395... 

PolyChexamethylene sebacate)/Poly(dimethyl siloxane) Block Copolymer. 

Jl hermally stable elastomers and polymers include fluorocarbon elastomers, polyorganophosphazenes, silicone elastomers, siloxane block copolymers (including the dodecacarborane block copolymers [Dexsil elasto-... 

In addition to the termination of living poly(dichlorophosphazene) with phos-phoranimine-terminated poly(dimethylsiloxane), another method has been presented to synthesize poly(phosphazene-siloxane) block copolymers. Hydrosilyla-tion reactions of hydride-terminated poly(dimethylsiloxane) and allyl-terminated polyphosphazenes (210a, 210b) have been shown to yield polyphos-phazene-h/ocfc-polysiloxane-h/oc/c-polyphosphazene polymers (21 la, 21 Ib). ... 

All siloxane block copolymers may be synthesized by the sequential copolymerization of two cyclotrisiloxane monomers. For example, unsubstituted hexamethyicyclotrisiloxane, D3, was first polymerized, and, before full conversion of this monomer, 2,4,6-trivinyltrimetiiylcyclotrisiloxane, V3, was added to the polymerization system [11]. The obtained block copolymer showed a high topological purity and a low polydispersion, MJM = 1.1. 

C2BioHioSi(CH3)20SiR R"0— with molecular weights up to 250,000 . In a related study a high-temperature-resistant polymer is prepared from l,7-C2BioHio-l,7-[Si(CH3)20H]2 and (CH3)2Si[N(CH3)2]2 . A carborane-siloxane block copolymer with 1,7-C2BioHio units is prepared by the reaction of a ureidosilane-terminated polysulfone hard block with a carborane-silanol-terminated carborane-siloxane oligomer . 

Figure 6.26. Swelling as a function of solubility parameter of the swellant at 25 C of ABA siloxane block copolymers cast from two different solvents at 25°C. (O) BC-2 ( = 9.1) from o-chlorohexa-hydrotoluene ( ) BC-2 = 9.6) from o-dichlorocyclohexane. (Fritzsche and Price, 1971.)...

Figure 6.27. Optical micrograph for a thin film of ABA siloxane block copolymer BC-1 after heating for 45 min at 500°C. Marker equals 0.5 /im. (Fritzsche and Price, 1970.)...

Pei X, Chen G, Fang X. Preparation and characterization of poly(imide siloxane) block copolymers based on diphenylthioether dianhydride isomer mixtures. High Perform Polym 2011 23(8) 625-32. 

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