Polyolefin hybrids

Synthesized polymer hybrids based on polyolefins are expected to possess the properties of each polymer segment. Several methodologies for the preparation of polyolefin hybrids have been reported in recent papers [27,28]. In particular, processes such as radical, anionic, cationic polymerizations and... 

Table 1 Preparation results of polyolefin hybrids, PE-fc-PMMA, by ATRPa...

Using living conditions with the state-of-the-art in catalyst technologies, crystal-amorphous polyolefin hybrids can be synthesized by successive polymerization, for instance, homo-polymerization and co-polymerization, of olefin monomers. By this methodology, block copolymers of polymer hybrids can be obtained. 

As mentioned, polymer hybrids based on POs are effective as a compati-bilizer between the olefinic materials and polar ones. Furthermore, some polymer hybrids, such as PP-g-PMMA, etc., show good mechanical strength as polymer materials. On the other hand, surface modification of the molded polymer is one of the most attractive methods to let polyolefin materials functionalize. In this sense, surface polymerization of functional monomers on polyolefins is an important subject for polyolefin hybrids. As previously referred to, the growth of PS on PP via the RAFT process has been reported [92]. 

Novel Polyolefin Hybrids via Controlled/Living Radieal Polymerization... 

Figure 2. Some Synthetic Examples of Polyolefin Hybrids...

Some synthetic examples of polyolefin hybrids are shown in Figure 2. RAFT polymerization of PE-/-CTA for MMA was initiated by AIBN in toluene at 60 °C. PE-/)-PMMA (PMMA contents 23 wt%) was successfully obtained . PE-/)-PMMA having the contents of PMMA (73 wt%) was yielded from PE-g-Br by ATRP for MMA with RuCl2(PPh3)3/Bu2NH as a catalyst. ATRP for acrylonitrile/styrene using PP-g-Br as a PO-MI was carried out to produce PP-g-AS (poly(acrylonitrile-co-styrene)). Then, EBR-g-PS was obtained from EBR-g-Br as a PO-Ml by ATRP for styrene. By selecting the kinds of PO-MIs and polar monomers for CRP, various kinds of PO hybrids have been obtained. 

One of the most promising applications of polyolefin hybrids is a compatibilizer for blend polymer for polyolefin and non-polyolefin. In Figure 7, TEM micrographs of PP/PMMA and EBR/poly(lactic acid) (PLA) blend polymers with and without polyolefin hybrids as a compatibilizer are displayed. Figure 7(a) represents the phase stracture of a PP/PMMA (62/38 wt%) blend polymer. Since PP and PMMA are immiscible, huge PMMA domains (> 20 pm) exist in the PP matrix. When 5 wt% of PP-g-PMMA (PMMA contents 38 wt%) was added to this blend polymer as a compatibilizer, PMMA domains were finely dispersed as is shown in Figure 7(b). As a result, the physical properties for both FM and FS were drastically enhanced from 35.3 MPa for FS and 1800 MPa for FM to 61.4 MPa for FS and 2200 MPa for FM, respectively. 

J/m). From these results, it was confirmed that polyolefin hybrids possess high potential as a compatibilizer for a polyolefin/polar polymer alloy system. 

The syntheses, properties and potential applications of polyolefin/non-polyolefin hybrid polymers, Polyolefin Hybrids , via controlled/living radical polymerization have herein been introduced. Polyolefin Hybrids can control the phase stractures, and the surface stmctures on molded polyolefin materials. Polyolefin Hybrids can enhance the physical properties of polyolefins as well as add new properties such as hydrophilicity and antibacterial properties to them. Novel value-added polyolefin materials, Polyolefin Hybrids , have great potential as new value-added materials. 

As mentioned above, the cleavage of Si-Si-bonds in polysilanes upon irradiation with UV-light is very efficient and results in the formation of silicon radicals. These radicals react with olefins to initiate radical polymerizations. Especially the polymerization of methylmethacrylate and styrene with a variety of polysilanes as photoinitiators has been studied in detail [104]. The advantage of this kind of initiation is the possibility to prepare polysilane-polyolefin hybrids [105]. All modifications of radical polymerizations, such as the atom transfer radical polymerization (ATRP), are possible with polysilanes as photoinitiators [106]. 

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