Poly siloxane copolymer

Figure 9.6 Frequent-use conditioning shampoo formulation (a cocamidopropyl betaine, ex Cognis, Dusseldorf Germany b hydrolysed wheat protein poly-siloxane copolymer, ex Croda Chems, Goole, UK c glycol distearate and laureth-4 and cocamidopropyl betaine, ex Cognis)...

Recently siloxane-imide copolymers have received specific attention due to various unique properties displayed by these materials which include fracture toughness, enhanced adhesion, improved dielectric properties, increased solubility, and excellent atomic oxygen resistance 1S3). The first report on the synthesis of poly(siloxane-imides) appeared in 1966, where PMDA (pyromellitic dianhydride) was reacted with an amine-terminated siloxane dimer and subsequently imidized 166>. Two years later, Greber 167) reported the synthesis of a series of poly(siloxane-imide) and poly(siloxane-ester-imide) copolymers using different siloxane backbones. However no physical characterization data were reported. 

The films were then thermally cycled at tOO, 200 and 300°C for an hour at each temperature in a forced air convection oven to complete the cyclization. The solution imidization procedure has been further described by Summers, et. al. (42,43). A representative structure for the poly(imide siloxane) copolymers is depicted in Figure 5. 

Resist solutions of o-cresol novolac-siloxane copolymers were prepared as 15 w/v % solutions of the polymer in 2-methoxyethyl acetate using 20 wt % (based on polymer) of the positive sensitizer. Poly(hydroxystyrene) and 2-methyl resorcinol copolymers were spun into films from 2-methyl tetrahydrofuran. Solutions were filtered through successive 1.0, 0.5 and 0.2 pm filters and stored in... 

Structure of phenolic resin-poly(dimethyl siloxane) copolymers. 

MOLECULAR WEIGHT DETERMINATION OF POLY(DIMETHYL SILOXANE) COPOLYMERS VIA GEL PERMEATION CHROMATOGRAPHY... 

THERMAL CHARACTERIZATION OF POLY (DIMETHYL SILOXANE) COPOLYMERS WITH POLY (HYDROXY STYRENE) AND 2-METHYL... 

Observations Two modified poly(isobomyl-b-siloxane) copolymers were prepared con-... 

However, even at relatively low SAN levels, the blends can become hazy or opaque. Transparent compositions can be obtained by using a poly(siloxane)/PC copolymer instead of pure PC (25). Thin-walled articles can be successfully fabricated from such a composition. The SAN should not contain more than 25% of AN. 

It is believed that the transparency of the poly(siloxane)/PC copolymer is related to the size and the distribution of the siloxane units within the copolymer. The distribution may be controlled by the method of preparation. 

Further, methods using phase transfer catalysts are suitable for the production of transparent poly(siloxane)/PC copolymers (27). As phase transfer catalyst a methyltributyl ammonium salt is used. 

It is surprising that poly(siloxane)/PC copolymer and SAN can form a transparent blend because the refractive index of poly(di-methyl siloxane) (PDMS) is around 1.4, which is very different from that of SAN (25). Moreover, PDMS can form a transparent blend with SAN that would not form a transparent blend with PC. Refractive indices of some polymers are summarized in Table 10.6. 

Poly(methyl methacrylate)-g-poly(dimethylsiloxane) copolymers have been prepared by free radical copolymerizations of acrylate-functional siloxane macromonomers (29) with methyl methacrylate. Siloxane macromonomers (29) of between 1,000 and 20,000 molecular weight were utilized to give a range of copolymers with between 4 and 17 wt% silicone115. 

The original and by far the most widely available fluorosilicone since its introduction in the 1950s is polymethyltrifluoropropylsiloxane (PMTFPS), more rigorously known as poly[methyl(3,3,3-trifluoropropyl)siloxane] or poly[methyl(lH,lH, 2H,2H-trifluoropropyl)siloxane]. Unless specifically mentioned, the unfluorinated carbons are those nearest to silicon, i.e., poly(methylnon-afluorohexyl)siloxane (PMNFHS) is poly[methyl(lH,lH,2H,2H-nonafluoro-hexyl)siloxane]. Currently, only copolymers of PMTFPS and PMNFHS with poly siloxane (PDMS) are available commercially.79... 

Fig. 15. Thermal gravimetric analysis in an air atmosphere of poly(siloxane imide)-seg-mented copolymers of various siloxane concentrations, indicating char yield proportional to siloxane content...

Table 3. Weight change incurred by homopolymers, poly(siloxane imide) segmented copolymers, and blends with polybenzimidazole due to exposure to high energy, high flux atomic oxygen3 ...

Poly(siloxane imide)-segmented copolymer 10% siloxane 4.54... 

Blend of poly(siloxane imide) copolymer (75%) and PBI (25%) total siloxane content 30% +2.95... 

Kapton Kapton coated with -1500 A poly(siloxane imide) copolymer with 50% siloxane 22.93 5.96... 

Yoon TH, Arnold CA, McGrath JE (1989) Titanium 6/4 single lap shear adhesive performance of polyimide homopolymers and poly(siloxane imide) segmented copolymers. Mater Res Soc Symp Proc 153 (Interfaces Polym Met Ceram) 211... 

Spontak RJ, Samseth J, Bedford SE (1991) Structure in cast films of poly(siloxane-im-ide) copolymers. Eur Polym J 27(2) 109... 

Arnold CA, Chen DH, Chen YP, Waldbauer RO, Rogers ME, McGrath JE (1990) Miscible blends of poly(siloxane imide) segmented copolymers and polybenzimidazole as potential high performance aerospace materials. High Perfm Polym 2(2) 83... 

Arnold CA, Summers JD, Chen YP, Yoon TY, McGrath BE, Chen D, McGrath JE (1989) Soluble polyimide homopolymers and poly (siloxane imide) segmented copolymers with improved dielectric behavior polyimides In Feger C, Khojasteh MM, McGrath JE (eds) Materials chemistry and characterization. Elsevier, Amsterdam... 

A significant amount of information regarding the uses of silicone surfactants is still found primarily in the patent art, but the major applications have recently been reviewed in journals. Silicone (or siloxane) surfactants are also called silicone polyethers (SPEs), polyalkylene oxide silicone copolymers, silicone poly(oxyalkylene) copolymers and silicone glycols. The International Cosmetic Ingredient Nomenclature and the Cosmetic, Toiletry and Fragrance Association (CTFA) adopted name is dimethicone copolyol. 

The NMR data presented above reveal a dynamic heterogeneity of filled PDMS in the frequency range from about 10 kHz to 100 MHz. To determine whether the heterogeneity remains at lower fi equencies, dynamic mechanical measurements are performed. The results for cured, unfilled silicon rubber are compared with those for filled samples containing different fraction of hydrophilic Aerosil (380 m g ). For a more straightforward analysis of the mechanical experiments, a random poly(dimethyl/methyl-phenyl) siloxane copolymer containing approximately 90 mol% dimethyl- and 10 mol% methylphenyl-siloxane units has been used for sample preparation. This copolymer is fully amorphous over the whole temperature range. The results of torsion experiments at a frequency of 1.6 Hz are shown as a function of temperature in Fig. 7. 

---