|Andrew Mark Spring||Last modified date：2023.05.09|
Associate Professor / Department of Molecular and Materials Sciences (MMS) / Department of Internationalization and Future Conception / Faculty of Engineering Sciences
|Andrew Mark Spring||Last modified date：2023.05.09|
|1.||Andrew M. Spring, Living Polymerizations for Engineering Applications
, CSS-EEST22, 2020.10, Well-controlled living polymerization mechanisms allow a fine tuning of bulk polymer properties to suit a range of high-tech engineering applications. Ring Opening Metathesis Polymerization (ROMP) is one of the most versatile and interesting of these techniques. The key requirement is that monomers must be cyclic alkenes which exhibit a large degree of ring strain. Typically, Grubbs catalysts are utilized to afford the narrow dispersity homopolymers, random copolymers, block copolymers and other more complex macromolecules..
|2.||Andrew Mark Spring, Synthesis and Characterization of Poly(norbornene-dicarboximides) and their Application as Electro-optic Polymeric Materials , SPSJ, 2014.12, The academic interest in poly(norbornene-dicarboximides) (poly(NDI)s) has increased substantially as a consequence of their favorable thermal, mechanical and optical properties, giving them a range of practical uses in optics. Provided that the cyclic monomers exhibit a high ring strain and low steric hindrance ROMP allows the preparation of well-defined homopolymers, random copolymers, block copolymers and polymer brushes.
An optimal organic electro-optic (EO) material must exhibit a large EO coefficient, optical transparency, thermal stability, temporal stability and a good solubility. These key requirements can be met by the use of poly(norbornene-dicarboximide) (NDI) homopolymers and polymer brushes with an NDI backbone and methyl methacrylate (MMA) side arms. The EO affect quantifies the relationship between the refractive index change (Δn) of a material upon application of an electric field (E). The magnitude of this change is related to the materials EO coefficient (r33) as described by the equation: Δn=-1/2n3r33E. Typical FTC chromophores encompass a strongly donating aromatic amine, an extended thiophene bridge and a strong tricyano containing heterocyclic electron accepting moiety. We have manipulated the structures of FTC chromophores in order to tune the properties, enhancing the hyperpolarizability and steric interactions and investigated the feasibility of using various Poly(norbornene)dicarboximide homopolymers, copolymers and polymer brushes as hosts for such chromophores.
|3.||Andrew Mark Spring, Electro-optic Polymeric Materials derived from High Tg Norbornene-Dicarboximide (NDI) Homopolymers and NDI / MMA Polymer Brushes., SPSJ, 2014.09, Over the last decade, organic electro-optic (NLO) materials have undergone significant developments in both the range of polymer architectures available and the selection of photonic devices which they can be utilized in. Key material properties include the ability to exhibit a large EO coefficient, optical transparency as not to impede device utilization, thermal stability to survive the harsh poling conditions and lastly but not least important, they should be highly soluble in a range of common organic solvents to facilitate their solution casting onto a range of conductive substrates. Poly(norbornene-dicarboximide) (NDI) homopolymers as well as polymer brushes derived from an NDI backbone, with methyl methacrylate (MMA) side arms display many of these important features..|
|4.||Andrew Mark Spring, Recent Innovations in Electro-optic Polymeric Materials and Chromophore Design., SPSJ, 2014.05, Abstract: Organic electro-optic (NLO) materials have undergone significant developments in both the range of polymer architectures available and the selection of photonic devices which they can be utilized in. Polymers were initially utilized in simple host-guest dispersions, with the next logical step being the side chain system. The practical limitations of these two architectures were later addressed by the cross-linked, dendritic, brush, hyper branched and self-assembled EO-polymers. Whichever specific means of immobilization is utilized, the common requirements are that the EO material must exhibit a large EO coefficient, be optically transparent as not to impede device utilization, be thermally stable to survive the harsh poling conditions and lastly but not least important, they should be highly soluble in a range of common organic solvents to facilitate their solution casting onto a range of conductive substrates..|
|5.||Andrew Mark Spring, An Enhanced Host-Guest Electro-Optical Polymer System using Poly(norbornene-dicarboximides) via ROMP., SPSJ , 2012.12, As our candidate host polymer we selected high Tg poly(NDI)s which were prepared via ROMP. By catalyst selection (G1 or G2), polymers with a 98% or 52% trans microstructure were produced. In this paper we investigated the relationship between polymer microstructure and molecular weight on the r33, in order to identify the optimum host polymer.
The monomer Cy(NDI) (1) (Scheme 1) was prepared according to the literature. As a consequence of the high ring strain, polymerization was initiated by G1 or G2 and the molecular weight was controlled by manipulating the [monomer] / [initiator] ratio. Two series of poly(NDI)s, as shown in Scheme 1 (2a-f) and (3a-f) were prepared. Polymerization by G1 yielded trans rich polymers (98% trans) whilst G2 gave polymers with a (52% trans) microstructure. The four polymers 2a, 2f, 3a and 3f were selected to investigate the effect of microstructure and polymer molecular weight on the r33. Two chromophores were used to evaluate poly(NDI) as a host, one having a tertbutyldiphenylsilane large electron donating substituent (C1) and one un-substituted (C2), with all results being compared to the control polymer PMMA. By using the high trans content poly(NDI)s as hosts (2a and 2f) and chromophore C1 as a guest, we observed a maximum r33 of 93 pm/V which is a 70% enhancement compared to PMMA. The optimum poling temperature for this system was probed in order to maximize the r33 signal (Figure 1). It was found that the maximum r33 was achieved at a poling temperature of 137°C, this value is 63°C lower than the Tg of the host polymer. The poly(NDI) systems also displayed excellent temporal stability at 85°C after 500 hours, which may be attributed to the high Tg of the poly(NDI) hosts (Figure 2).
|6.||Andrew Mark Spring, Novel Optical Polymer Hosts via Ring Opening Metathesis Polymerization (ROMP), SPSJ , 2012.05, In the goal to achieve a high electrooptic coefficient (r33 > 100 pm/V), there are three common strategies. Firstly utilization of a high Tg polymer (typically hyperbranched) as a host for a high hyperpolarizability (β) chromophore (Guest-Host), alternatively appending directly the chromophore via some covalent linking moiety to the polymer (Side-Chain)1 and finally post polymerization crosslinking by addition of a small quantity of crosslinking molecule or spontaneous heat/light induced chemical reaction (Cross-linked). Our research while attempting all three of the previous strategies is primarily focused on the design and synthesis of a small library of strained norbornene derived monomers, with various active substituents, which may be polymerized via ring opening metathesis polymerization (ROMP) using the commercially available Grubbs initiators (Grubbs 1st and 2nd generation). Such polymers have been shown to exhibit a narrow polydispersity, controllable molecular weights, rapid polymerization and allow the preparation of well defined block copolymers. Control over the Tg, refractive index and resistivity is feasible by this method. Generally for any polymer to be a successful candidate for EO host, it must exhibit key physical properties such as a high optical
transparency, high thermal stability and a high glass transition temperature (Tg). PolyN-norbornene dicarboximide’s as well as similar polynorbornene’s have demonstrated such favorable properties as well as the additional attractive feature of being living polymerizations.
|7.||Andrew Mark Spring, Poly(Phenylenevinylenes) by Microwave Assisted Ring Opening Metathesis Polymerization., IUPAC , 2009.06, Excellent control in the synthesis of MEH-PPV can be achieved
by microwave assisted, ring-opening metathesis polymerization
(ROMP) of [2.2]paracyclophanedienes..