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Modern rocket propellants, gun propellants, and explosives are an adaptation of the basic concept of a formulation consisting of a solid oxidizer and fuel held in a polymeric matrix. In 1978, we embarked on a research effort to synthesize energetic polymeric binders specifically designed for propellant applications. A modified cationic polymerization technique was developed, which allowed the synthesis of polymers to predetermined molecular weight and functionality, and the concept of energetic polyoxetanes was presented. Further work has now resulted in nitrate ester, nitramine polymers, copolymers, and recently nitro, cubane and carborane polymers. The latter is the subject of this paper. Boron or boron compounds have been used as a burning rate modifier and as a metal fuel source in solid propellant motors. Migration of these chemicals in the propellant grain is a continuous and serious problem. We proposed that a urethane curable polyether glycol with a carboranyl functionality would solve migration problems. Oxetane-carboranes would be good candidates as monomers for these carboranyl pendant polymers. These monomers could be homopolymerized or co-polymerized with other oxetanes for specific properties. This paper describes the synthesis, characterization, and polymerization of oxetane-carborane monomers.

Large scale synthesis of the cubane oxetane monomer, CUBOX, was developed during the last reporting period. The key intermediate from commercially available cubane dicarboxylic acid is cubane monocarboxylic acid. Several routes to its synthesis were outlined in the Fifth Quarterly Summary. The original method supplied by Dr. Eaton was abandoned when scale-up gave poor yields. In this method, the n-hydroxypyridine-2-thion ester undergoes free radical decarboxylation in ter-butylmercaptan. Also the odor (natural gas) of ter-butylmercaptan could not be contained and this was a concern in our laboratory. Energetic binders.

The objective of the research was to investigate the synthesis and polymerization of energetic and nonenergetic monomers to provide thermoplastic elastomers for use as binders in solid gun propellants and cast-cured explosives. The polymer systems investigated were designed to meet the requirements of the Navy's LOVA (low vulnerability ammunition) program. (Author)

Three general synthetic routes to the preparation of energetic oxetanes and tetrahydrofurans were investigated during the first year of the program. Subsequently, 3-(2-fluoro-2,2-dinitroethyl-3-methyloxetane (FOE) was prepared and polymerized to give oligomers with molecular weights ranging from 6,000 to 15,000. Efforts to develop a general synthetic route to 3-nitroalkyl substituted oxetanes starting with methylene malonate were not successful. However, work on an alternative general route to oxetanes afforded oxetane 3,3-diacetic acid in low yield. This material could be used to prepare a series of nitro esters of oxetane, but this work was terminated as our experience has shown that cationic polymerization of esters does not produce significant conversion of the monomer. Work on a general route to nitroalkyl-substituted tetrahydrofurans resulted in 3-(2,2-dinitropropyl)tetrahydrofuran (3-DNPTHF), which was prepared using a synthetic route of general applicability to other 3-substituted tetrahydrofurans. A preliminary polymerization study yielded dimer and trimer, suggesting that polymerization was possible.

During this first year of the program, three general synthetic routes to the preparation of energetic oxetanes and tetrahydrofurans were investigated. Efforts to develop a general synthetic route to 3-nitroalkly-substituted oxetanes starting with methylene malonate were not successful. However, one specific oxetane monomer was prepared to provide an immediate subject for polymerization studies. (Author)

The objective of our research is to synthesize energetic polyether binders with the ability to undergo reversible physical crosslinking at temperatures compatible with high energy propellant ingredients. Commercially available thermoplastic elastomers fail to meet our criteria because of excessively high processing temperatures and melt viscosity, high modulus and low stress/strain capability. It was proposed to synthesize ABA type block polymers with the A blocks being polymers able to form crystalline structure (as opposed to glasses) having a sharp melting point of 85-95C.

The objective of this research was to develop the synthesis and polymerization of energetic and non-energetic monomers for use as binders in solid gun propellants, melt cast PBXs and cast-cured PBXs. The polymers are designed to meet the requirements of the Navy's LOVA (Low Vulnerability Ammunition) program. During this reporting period we have developed a series of azido, nitrate ester and mixed azido/nitrate ester urethane curable prepolymers. Initial evaluation reveals that these polymers meet thermal and chemical stability criteria for continued study. We have synthesized alternating crystalline and amorphous block copolymers, based on non-energetic cyclic ether monomers, that exhibit thermoplastic elastomer behavior. The melting point transition (working) temperature meets the program goals of 90 deg C. The resulting melt cast polymer showed the typical tough, high modulus properties of thermoplastic elastomers with a low melt viscosity at projected formulation temperatures. Physical integrity is maintained to within 5 deg C of the working temperature. These polymers exhibit endothermic decomposition/depolymerization at elevated temperatures.

The present study involves crystalline block copolymers based on poly(3,3-bis(ethoxymethyl)oxetane, polyBEMO, and random copolymers based on other either forming monomers. The objective of the work is to generate a block copolymer consisting of crystallizable polyether end blocks based on poly(BEMO) and an amorphous rubbery center block based on the polyether random copolymers. This paper will examine the interrelationships among glass and melting transition behavior, viscoelastic characteristics, tensile properties, and morphological features of these new block copolymers. The properties of the block copolymers will be compared with those of the homopolymer poly(BEMO)., Prepared in cooperation with East Stroudsburg Univ., PA and Thiokol Chemical Corp., Brigham City, UT. Wasatch Div.

We present early results from the JCMT (James Clerk Maxwell Telescope) Plane Survey (JPS), which has surveyed the northern inner Galactic plane between longitudes ℓ = 7° and ℓ = 63° in the 850-μm continuum with SCUBA-2 (Submm Common-User Bolometer Array 2), as part of the JCMT Legacy Survey programme. Data from the ℓ = 30° survey region, which contains the massive-star-forming regions W43 and G29.96, are analysed after approximately 40 per cent of the observations had been completed. The pixel-to-pixel noise is found to be 19 mJy beam−1 after a smooth over the beam area, and the projected equivalent noise levels in the final survey are expected to be around 10 mJy beam−1. An initial extraction of compact sources was performed using the FELLWALKER method, resulting in the detection of 1029 sources above a 5σ surface-brightness threshold. The completeness limits in these data are estimated to be around 0.2 Jy beam−1 (peak flux density) and 0.8 Jy (integrated flux density) and are therefore probably already dominated by source confusion in this relatively crowded section of the survey. The flux densities of extracted compact sources are consistent with those of matching detections in the shallower APEX (Atacama Pathfinder Experiment) Telescope Large Area Survey of the Galaxy (ATLASGAL) survey. We analyse the virial and evolutionary state of the detected clumps in the W43 star-forming complex and find that they appear younger than the Galactic-plane average.

We present the first data release of the James Clerk Maxwell Telescope (JCMT) Plane Survey (JPS), the JPS Public Release 1 (JPSPR1). JPS is an 850-µm continuum survey of six fields in the northern inner Galactic Plane in a longitude range of ℓ = 7°–63°, made with the Sub-millimetre Common-User Bolometer Array 2 (SCUBA-2). This first data release consists of emission maps of the six JPS regions with an average pixel-to-pixel noise of 7.19 mJy beam−1, when smoothed over the beam, and a compact-source catalogue containing 7,813 sources. The 95 per cent completeness limits of the catalogue are estimated at 0.04 Jy beam−1 and 0.3 Jy for the peak and integrated flux densities, respectively. The emission contained in the compact-source catalogue is 42 ± 5 per cent of the total and, apart from the large-scale (greater than 8 arcmin) emission, there is excellent correspondence with features in the 500-µm Herschel maps. We find that, with two-dimensional matching, 98 ± 2 per cent of sources within the fields centred at ℓ = 20°, 30°, 40° and 50° are associated with molecular clouds, with 91 ± 3 per cent of the ℓ = 30° and 40° sources associated with dense molecular clumps. Matching the JPS catalogue to Herschel 70-µm sources, we find that 38 ± 1 per cent of sources show evidence of ongoing star formation. The images and catalogue will be a valuable resource for studies of star formation in the Galaxy and the role of environment and spiral arms in the star formation process.

We present the first data release of the James Clerk Maxwell Telescope (JCMT) Plane Survey (JPS), the JPS Public Release 1 (JPSPR1). JPS is an 850-µm continuum survey of six fields in the northern inner Galactic Plane in a longitude range of ℓ = 7°–63°, made with the Sub-millimetre Common-User Bolometer Array 2 (SCUBA-2). This first data release consists of emission maps of the six JPS regions with an average pixel-to-pixel noise of 7.19 mJy beam−1, when smoothed over the beam, and a compact-source catalogue containing 7,813 sources. The 95 per cent completeness limits of the catalogue are estimated at 0.04 Jy beam−1 and 0.3 Jy for the peak and integrated flux densities, respectively. The emission contained in the compact-source catalogue is 42 ± 5 per cent of the total and, apart from the large-scale (greater than 8 arcmin) emission, there is excellent correspondence with features in the 500-µm Herschel maps. We find that, with two-dimensional matching, 98 ± 2 per cent of sources within the fields centred at ℓ = 20°, 30°, 40° and 50° are associated with molecular clouds, with 91 ± 3 per cent of the ℓ = 30° and 40° sources associated with dense molecular clumps. Matching the JPS catalogue to Herschel 70-µm sources, we find that 38 ± 1 per cent of sources show evidence of ongoing star formation. The images and catalogue will be a valuable resource for studies of star formation in the Galaxy and the role of environment and spiral arms in the star formation process.