Cellulose, polystyrene grafted

Waltcher, I., R. Burroughs jr., and E. C. Jahn Grafting to cellulose. International congress of pure and applied chemistry, Stockholm, 1953. Burroughs jr., R. The preparation and characterization of a cellulose polystyrene graft polymer. Thesis, State University College of Forestry, Syracuse, N. Y., 1955. 

Bonding of hydrophobic plastic materials to wood to create new wood-plastic (polystyrene) materials with improved mechanical and physical properties that incorporate the desirable features of each constituent is difficult to achieve. This is due to poor interfacial adhesion between the wood and polystyrene components because of their inherent incompatibility. New, well-defined, tailored cellulose-polystyrene graft copolymers have recently been prepared using anionic polymerization techniques. Preliminary bonding studies showed that these graft copolymers can function effectively as compatibi-lizers or interfacial agents to bond hydrophobic plastic (polystyrene) material to wood, evolving into a new class of composites. 

This chapter reports successful initial efforts to bond wood in the presence of hydrophobic plastic material [polystyrene (PS)] using well-defined and tailored cellulose-polystyrene graft polymers as compatibilizers or interfacial agents. The synthesis of these tailored cellulose graft polymers is also presented. 

Preparation of Cellulose-Polystyrene Graft Copolymers. The polystyr-yl mono- and di-carbanions were prepared in THF at -78 °C by using n-butyl lithium and sodium naphthalene as the initiators, respectively. The carban-ions were reacted with dry carbon dioxide. The products were precipitated in methanol, filtered, washed with water and methanol, and dried. Size exclusion chromatography (SEC) established that the molecular weight of the polystyryl monocarboxylate was 6,200 and that of the polystyryl di-carboxylate 10,2000. The mono- and di-carboxylates were reacted with mesylated cellulose acetate in dimethylformamide at 75 °C for 20 h to give the cellulose-polystyrene graft copolymer (GP 1) and crosslinked cellulose-polystyrene graft copolymer (GP 2), respectively. 

Synthesis of Tailor Made Cellulose-Polystyrene Graft Copolymers... 

Encouraging results on the bonding of plastics to wood using tailor-made cellulose-polystyrene graft polymers as compatibilizers or interfacial agents may offer a new approach to the engineering of wood-plastic products with improved mechanical and physical properties for a variety of applications. It also holds the potential of opening up new markets for renewable resources in the form of woody materials. For example, polystyrene production is currently 3.9 billion... 

An effective method of NVF chemical modification is graft copolymerization [34,35]. This reaction is initiated by free radicals of the cellulose molecule. The cellulose is treated with an aqueous solution with selected ions and is exposed to a high-energy radiation. Then, the cellulose molecule cracks and radicals are formed. Afterwards, the radical sites of the cellulose are treated with a suitable solution (compatible with the polymer matrix), for example vinyl monomer [35] acrylonitrile [34], methyl methacrylate [47], polystyrene [41]. The resulting copolymer possesses properties characteristic of both fibrous cellulose and grafted polymer. 

The properties of cellulosic graft copolymers have been studied to a considerable extent but mainly in the form of grafted fibers or films of ill-defined composition. However, a few properties have been measured on well defined grafts (147). It was found that solutions of cellulose acetate-polystyrene grafts in dimethyl formamide are less tolerant to the addition of polystyrene than cellulose acetate itself. This result was attributed to the greater coil expansion in the case of the graft copolymer. On the other hand, the tolerance of the grafts to each homo-... 

Fig. 5. Intrinsic viscosity of a cellulose acetate graft copolymer (44.1% combined polystyrene) and the corresponding homopoly-mers in toluene-acetone mixtures...

Besides classical resin beads, other polymeric carriers were also used for the synthesis ofpeptide libraries in various formats. Poly aery late-grafted polypropylene pins were used for the synthesis of the first combinatorial chemical library [1,2], This type of support continues to be heavily used in multiple peptide [27] and non-peptide [28] library synthesis. Cellulose paper, originally used by Frank et al. as a solid-phase support for oligodeoxy-ribonucleotide synthesis [29], has also been used as the support for multiple SPOT synthesis of peptide libraries [30,31], Polystyrene-grafted polyethylene film (PS-PE) may also be used in combinatorial peptide library synthesis [32], The specific feature of the membrane type of carrier is its dividability. This feature has been used for the synthesis of libraries with a nonstatistical distribution of library members, where no compound is missing and none is represented more than once [33],... 

Figure 2. Continuous three-dimensional network of plastic (polystyrene) linked to wood via a cellulose-polysytrene graft copolymer.

A peptide library can be synthesized using the SPOT synthesis technique to form a low-density peptide spot array (e.g., 25 spots/cm ). In this method, different peptides are synthesized in situ as low-density arrays on cellulose membrane or paper (8). The volume of Fmoc-amino acids and coupling reagents dispensed creates a specific SPOT size that determines both the scale of reaction and the absolute number of peptides that can be arranged on an area of a membrane. Cotton (another form of cellulose) and polystyrene-grafted polyethylene film segments also have been used as solid supports. Recently, polymeric membranes that are chemically, mechanically, and thermally more stable have been developed, which include hydroxy-functionalized PEG acrylate polypropylene membranes and an amino-functionalized ester-free PEG... 

Morandi G, Heath L, Thielemans W (2009) Cellulose nanocrystals grafted with polystyrene chains through surface-initiated atom transfer radical polymerization (SI-ATRP). Langmuir 25 8280-8286... 

Figure 5 shows the TGA of the polystyrene-cellulose acetate graft polymer in comparison with the polystyrene-oxycellulose graft polymers. The TGA curve of the polystyrene-cellulose acetate is clearly different from the polystyrene-oxycellulose graft polymers and the cellulose acetate. It shows much Biore thermal stability than the other three. 

Wu et al. (1992) measured the advancing water contact angles on the top surface of modified membranes by plasma surface polymerization of polystyrene grafting of cellulose acetate membranes to test their hydrophobicity. The water contact angles were found to increase with the radiation time and presented a minimum with discharge power. 

A large variety of polymers has been considered. In the beginning, polystyrene and styrene/ divinylbenzene copolymers (Merrifield resins) were by far the most used.73 Then others were tested such as polyvinyls,47-50,61-64 polyacrylates,72 4,75 and cellulose.76,77 Most commonly, diphenylphos-phane groups were grafted on the polymeric support, either directly or via one CH2 group. 

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